COMPOSITE MATERIAL

INTRODUCTION

[0001] The present invention relates to a composite material comprising a continuous 2- dimensional carbon thin film and at least one further material. The present invention also relates to processes of making the composite material and certain uses of the composite material. In particular, the present invention further relates to heterostructures, electronic components and electronic devices comprising the composite material of the present invention.

BACKGROUND OF THE INVENTION

[0002] The extensive commercial potential of carbon residue materials (including 2D materials) such as graphene, graphene oxide, graphite, graphite oxide and carbon nanotubes and of further 2D materials including boron nitrides, transition-metal dichalcogenides (TMDCs), a layer of metal oxides and single element materials such as silicene, germanene, stanene and phosphorene, is well documented owing to their exceptional electrical, thermal, chemical and mechanical properties. These materials have found application in areas as diverse as, energy storage and conversion, sensors, drug delivery, field emission devices, semiconductor devices, nano-scale electronic components and their uses include liquid and gas filtration, gas storage, energy storage, electronics, coatings, and medical applications.

[0003] Graphene-based materials have been studied for over four decades, including the transport properties in exfoliated graphene oxide layers, graphene grown on silicon carbide and copper substrates. A variety of studies involve the use of chemically modified graphene (CMG) to make new materials. Of the available strategies, chemical exfoliation to form graphene oxide layers has been favoured in the mass production of graphene oxide. Production of large area graphene via chemical vapour deposition has led to high quality graphene.

[0004] Methods for producing layers of boron nitrides and transition-metal dichalcogenides, single layer metal oxides and single element materials such as germanene, stanene, silicene and phosphorene, are also known in the literature.

[0005] In many applications of 2D materials, the 2D material must be formed into a device. Such devices may include composite materials, and in particular composite materials formed as stacks of 2D materials in the vertical or horizontal direction. These composite materials are known as 2D heterostructures, in particular 2D vertically stacked heterostructures and 2D In-Plane heterostructures. These composite materials and devices and their applications are known to those skilled in the art, for example as described in "Stacking of Two-Dimensional Materials in Vertical and Horizontal Directions" Lim et.al., Chemistry of Materials (2014) 26, 4891 -4903.

[0006] The present invention was devised with the foregoing in mind.

SUMMARY OF THE INVENTION

[0007] The present invention relates to the formation of a composite material using novel continuous 2-dimensional carbon thin films having a film thickness of less than 20 nm and an area divided by thickness ratio (A/T) of greater than 10 ¹⁰ nm. These films have been defined and claimed in the Applicant's co-pending International Patent Application No. PCT/GB2016/051834. These films are produced by interfacial polymerisation of a polymeric film followed by reduction/carbonisation, as defined further herein.

[0008] These continuous 2-dimensional carbon thin films offer a wealth of advantages over similar materials that are presently available. Perhaps most notably, these continuous 2- dimensional carbon thin films have enhanced dimensional characteristics when compared with graphene and graphene-oxide type materials prepared according to currently available techniques. In particular, techniques such as micromechanical cleavage, epitaxial growth, chemical synthesis involving oxidation-intercalation and exfoliation have inherent limits in terms of the dimensions of the 2-dimensional carbon thin film or flakes they can produce, which typically have an area to thickness ratio of less than 10 ¹⁰ nm. In contrast, the continuous 2-dimensional carbon thin films used in the composites of the present invention typically have a thickness of less than 20 nm and an area divided by thickness ratio (A/T) of greater than 10 ¹⁰ nm.

[0009] Thus, according to a first aspect of the present invention there is provided a composite material comprising a 2-dimensional carbon thin film as defined herein and at least one further material. Suitably, the 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked or in-plane heterostructures. The the 2-dimensional carbon thin film and the at least one further material are suitably in intimate contact with one another.

[0010] According to a second aspect of the present invention there is provided a composite material comprising a continuous 2-dimensional carbon thin film that has a thickness of less than 20 nm and/or an area divided by thickness ratio (A/T) of greater than 10 ¹⁰ nm and at least one further material.

[0011] According to a third aspect of the present invention there is provided a composite material comprising a continuous 2-dimensional carbon thin film obtainable, obtained or directly obtained by a process defined herein and at least one further material, wherein the continuous 2- dimensional carbon thin film is as defined in the first aspect of the invention or has a thickness of less than 20 nm and/or an area divided by thickness ratio (A/T) of greater than 10 ¹⁰ nm.

[0012] According to a fourth aspect of the present invention, there is provided a composite material comprising a continuous 2-dimensional carbon thin film having a thickness of less than 20 nm, an area of greater than 0.0001 cm ² and a sheet resistance of≤21 kQ/square (e.g. 0.6-21 kQ/square and at least one further material.

[0013] According to a fifth aspect of the present invention, there is provided a composite material comprising a continuous 2-dimensional carbon thin film having a thickness of less than 20 nm, an area of greater than 0.0001 cm ² and a sheet resistance of ≤21 kQ/square (e.g. 0.6-21 kQ/square), and having the following atomic composition: 85 to 98% carbon, 1 to 10% oxygen, and 0.5 to 6% nitrogen, and at least one further material.

[0014] According to a further aspect, the present invention provides the use of a composite material as defined herein for gas storage and separation, electrode materials, heterostructures, transistors and electronic components, food packaging, plastics, condoms or as a separation membrane.

[0015] According to a further aspect, the present invention provides a use of composite material comprising a continuous 2-dimensional carbon thin film and at least one further material as defined herein in an application selected from tissue engineering, bio-imaging (e.g. contrast agents), the polymerase chain reaction, diagnostic devices, drug delivery, bio-microrobotics, blood sensing, electronics (e.g. in transistors, semiconductors, conducting electrodes, transparent conducting electrodes, conducting electrode on flexible supports, frequency multipliers, optoelectronics, Hall effect sensors, organic electronics, spintronics, optical modulators, infrared light sensors and/or photodetectors), membranes for liquid separation, solar cells (e.g. as charge conductors, light collectors and electrodes), in fuel cells, thermoelectric devices, photo-electro catalysis devices, coatings, supercapacitors, batteries, hydrogen storage, in sensors with adsorbed molecules, wearable devices, magnetic sensors, contaminant removal from gas and liquid streams, water purification, desalination, gas separation membranes, gas storage, molecular adsorbent, plasmonics and metamaterials, as lubricants, in radio wave adsorption, in redox devices, as nanoantennas, in sound transducers, as waterproof coatings, as coolant additives, as lubricant additives, as reference materials, in thermal management, as structural materials in composites and as catalysts to speed up the rate of chemical reactions.

[0016] According to a further aspect of the present invention, there is provided a process for the preparation of composite material as defined herein, wherein the continuous 2-dimensional carbon thin film is prepared using a process comprising the steps of: a) providing an organic polymeric thin film that has been prepared by an interfacial polymerisation process, said thin film having a thickness of less than 200 nm; and

b) subjecting the organic polymeric thin film of step a) to a carbonisation process; and wherein the continuous 2-dimensional carbon thin film is then combined with the at least one further material to prepare the composite.

[0017] According to a further aspect of the present invention, there is provided a process for the preparation of composite material as defined herein, where the material is prepared using a process comprising the steps of:

a) providing an organic polymeric thin film that has been prepared by an interfacial polymerisation process, said thin film having a thickness of less than 200 nm; and

b) stacking the organic polymeric thin film with at least one further material and c) subjecting the stack comprising the organic polymeric thin film and the at least one further material to a carbonisation process.

[0018] According to a further aspect of the present invention, there is provided a heterostructure comprising, or formed from, a composite material as defined herein.

[0019] According to a further aspect, the present invention provides an electronic component comprising a composite material or heterostructure as defined herein.

[0020] According to a further aspect, the present invention provides an electronic device comprising a composite material, heterostructure or electronic component as defined herein.

DETAILED DESCRIPTION OF THE INVENTION

2-dimensional carbon thin films

[0021] As described hereinbefore, the present invention utilizes a continuous 2-dimensional carbon thin film wherein the thin film has a thickness of less than 20 nm and an area divided by thickness ratio (A T) of greater than 10 ¹⁰ nm.

[0022] It will be understood that, unless otherwise specified, the term "continuous 2-dimensional carbon thin film" used herein refers to the product formable by subjecting an interfacially polymerised polymeric thin film to a carbonisation process defined herein which increases the fraction of carbon atoms within the polymeric thin film by chemically removing some or all non- carbon atoms. Accordingly, it will be appreciated that the continuous 2-dimensional carbon thin film is chemically distinct from graphene. Numerous embodiments and examples of the interfacially polymerised polymeric thin film are set out in the applicant's co-pending International Patent Application No. PCT/GB2016/051834.

[0023] In an embodiment of the invention, the 2-dimensional carbon thin film has a thickness of less than 20 nm (e.g. 1 -10 nm). Suitably, the 2-dimensional carbon thin film has a thickness of less than 6 nm. More suitably, the 2-dimensional carbon thin film has a thickness of less than 4 nm (for example, less than 3 nm or less than 2.5 nm).

[0024] In an embodiment, at least a portion of the thin film has a structure corresponding to graphene, graphene oxide or reduced graphene oxide. The hexagonal lattice structure of graphene will be well appreciated by those skilled in the art. Portions of the 2-dimensional thin films may also comprise structures, or functional groups that are common to graphene oxide and reduced graphene oxide, (e.g. -COOH, -OH and epoxy).

[0025] In an embodiment, the 2-dimensional carbon thin film is at least 80% carbon.

[0026] In an embodiment, the elemental composition (atomic %) of the thin film is as follows:

85 to 95% carbon, and

2 to 13% oxygen.

[0027] In an embodiment, at least a portion of the thin film has a structure corresponding to graphene, graphene oxide or reduced graphene oxide, and the thin film additionally comprises one or more nitrogen-containing moieties (e.g. pyrrolic nitrogen atoms, pyridinic nitrogen atoms, amino or cyano nitrogen atoms or quaternary nitrogen atoms). When the thin film comprises nitrogen-containing moieties, it will be understood that such moieties form an integral part of the thin film's structure, rather than being mere surface contamination.

[0028] In an embodiment, the elemental composition (atomic %) of the thin film is as follows:

85 to 98% carbon,

1 to 10% oxygen, and

0.5 to 6% nitrogen.

[0029] In an embodiment, the elemental composition (atomic %) of the thin film is as follows:

88 to 98% carbon,

1 to 6% oxygen, and

0.5 to 6% nitrogen.

[0030] In an embodiment, the elemental composition (atomic %) of the thin film is as follows:

90 to 98% carbon,

1 to 4% oxygen, and

0.5 to 6% nitrogen. [0031] In any of the elemental compositions recited above,≥ 50% of the carbon atoms are aromatic sp ² carbon atoms. Suitably, in any of the elemental compositions recited above,≥ 55% of the carbon atoms are aromatic sp ² carbon atoms. For example, in any of the elemental compositions recited above, 50-85% of the carbon atoms are aromatic sp ² carbon atoms. In any of these compositions, 3-45% of the nitrogen atoms may be pyridinic nitrogen atoms, 1 -17% of the nitrogen atoms are amino and cyano and/or 3-33% of the nitrogen atoms may be pyrrolic nitrogen atoms and/or 5-83% of the nitrogen atoms are quaternary nitrogen atoms and 1 -16% of the nitrogen atoms are N-oxides.

[0032] In an embodiment, at least a portion of the 2-dimensional carbon thin film has a structure corresponding to graphene, the thin film additionally comprising one or more atoms/moieties selected from -OH, C=0, -COOH, pyrrolic nitrogen atoms, pyridinic nitrogen atoms, amino and cyano nitrogen atoms, and quaternary nitrogen atoms.

[0033] In an embodiment, the 2-dimensional carbon thin film has a water contact angle value of 55-95°. Suitably, the 2-dimensional carbon thin film has a water contact angle value of 57-82 °. Most suitably, the 2-dimensional carbon thin film has a water contact angle value of 65-75°.

[0034] In an embodiment, the 2-dimensional carbon thin film is a smooth film, or a crumpled film. It will be understood that the term "crumpled" refers to the form of the film, which may contain a plurality or discernible ridges, trenches, grooves, corrugations of protrusions. More particularly, crumpled carbon films will be understood to be those having a root mean square roughness greater than 20 nm and median peak-to- valley value greater than 30 nm measured via atomic force microscopy. Smooth films will be understood to be those having a root mean square roughness below 1 nm (for example below 0.5 nm).

[0035] In an embodiment, the 2-dimensional carbon thin film has a BET surface area≥300 m¾ ^{" 1} . Suitably, the 2-dimensional carbon thin film has a BET surface area >400 m ² g ¹ . More suitably, the 2-dimensional carbon thin film has a BET surface area≥450 m ² g ^~1 . Most suitably, the 2- dimensional carbon thin film has a BET surface area≥500 m ² g ^~1 .

[0036] In an embodiment, the 2-dimensional carbon thin film has a BET surface area of 300-700 m¾ ^"1 . Suitably, the 2-dimensional carbon thin film has a BET surface area of 300-550 m ² g ¹ . More suitably, the 2-dimensional carbon thin film has a BET surface area of 350-550 m ² g ¹ .

[0037] In an embodiment, the 2-dimensional carbon thin film has pore volume of ≥ 0.15 cm ³ /g (e.g. 0.15-0.35 cm ³ /g). Suitably, the 2-dimensional carbon thin film has pore volume of ≥ 0.2 cm ³ /g. More suitably, the 2-dimensional carbon thin film has pore volume of ≥ 0.22 cm ³ /g. Most suitably, the 2-dimensional carbon thin film has pore volume of≥ 0.25 cm ³ /g. [0038] In an embodiment, the 2-dimensional carbon thin film has an average pore width of 0.3-0.7 nm. Suitably, the 2-dimensional carbon thin film has an average pore width of 0.45-0.6 nm.

[0039] In an embodiment, the 2-dimensional carbon thin film is conductive. Conductive carbon thin films represent an attractive prospect for electronic applications.

[0040] In an embodiment, the 2-dimensional carbon thin film is transparent. Suitably, the 2- dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥40% at a film thickness of 3 nm. More suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of >50% at a film thickness of 3 nm. Even more suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥55% at a film thickness of 3 nm. Even more suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥60% at a film thickness of 3 nm. Even more suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥65% at a film thickness of 3 nm. Even more suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of ≥70% at a film thickness of 3 nm. Yet more suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥75% at a film thickness of 3 nm. Yet more suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥80% at a film thickness of 3 nm. Most suitably, the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥85% at a film thickness of 3 nm.

[0041] In an embodiment, the continuous 2-dimensional carbon thin film has a sheet resistance of < 21 kQ/square (kQ/ci) (e.g. 0.6-21 kQ/square or 0.8-21 kQ/square). Suitably, the continuous 2-dimensional carbon thin film has a sheet resistance of < 15 kQ/square. More suitably, the continuous 2-dimensional carbon thin film has a sheet resistance of < 10 kQ/square. Even more suitably, the continuous 2-dimensional carbon thin film has a sheet resistance of≤ 8 kQ/square. Yet more suitably, the continuous 2-dimensional carbon thin film has a sheet resistance of < 6 kQ/square. Yet more suitably, the continuous 2-dimensional carbon thin film has a sheet resistance of ≤ 4 kQ/square. Most suitably, the continuous 2-dimensional carbon thin film has a sheet resistance of≤ 2.5 kQ/square.

[0042] In an embodiment, the continuous 2-dimensional carbon thin film has a transmittance of 80-90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of ≤ 21 kQ/square (e.g. 0.6-21 kQ/square or 0.8-10 kQ/square). Suitably, the continuous 2-dimensional carbon thin film has a transmittance of 80-90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of < 7.5 kQ/square (e.g. 0.8-7.5 kQ/square). More suitably, the continuous 2-dimensional carbon thin film has a transmittance of 80-90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of ≤ 5 kQ/square (e.g. 0.8-5 kQ/square). Even more suitably, the continuous 2-dimensional carbon thin film has a transmittance of 80-90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of < 3 kQ/square (e.g. 0.8-3 kQ/square).

[0043] In a particularly suitable embodiment, the continuous 2-dimensional carbon thin film has a transmittance of ≥ 90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of ≤ 20 kQ/square (e.g. 0.8-20 kQ/square). Suitably, the continuous 2-dimensional carbon thin film has a transmittance of ≥90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of ≤ 10 kQ/square. More suitably, the continuous 2-dimensional carbon thin film has a transmittance of >90% at 550 nm and 2.5-5 nm thickness and a sheet resistance of < 6 kQ/square.

[0044] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 100 kQ/square.

[0045] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 50 kQ/square.

[0046] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 35 kQ/square.

[0047] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 20 kQ/square.

[0048] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 10 kQ/square (e.g. 0.1 -10 kQ/square or 0.9-5 kQ/square).

[0049] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer or layers are selected from a reduced graphene oxide, graphene, carbon nanotubes (e.g. single-walled carbon nanotubes), TMDC, single layer metal and/or single layer metal oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of < 100 kQ/square. [0050] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer or layers are selected from a reduced graphene oxide, graphene, carbon nanotubes (e.g. single-walled carbon nanotubes), TMDC, single layer metal and/or single layer metal oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 50 kQ/square.

[0051] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer or layers are selected from a reduced graphene oxide, graphene, carbon nanotubes (e.g. single-walled carbon nanotubes), TMDC, single layer metal and/or single layer metal oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 35 kQ/square.

[0052] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer or layers are selected from a reduced graphene oxide, graphene, carbon nanotubes (e.g. single-walled carbon nanotubes), TMDC, single layer metal and/or single layer metal oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of < 20 kQ/square.

[0053] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer or layers are selected from a reduced graphene oxide, graphene, carbon nanotubes (e.g. single-walled carbon nanotubes), TMDC, single layer metal and/or single layer metal oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 10 kQ/square (e.g. 0.1 -10 kQ/square or 0.9-5 kQ/square).

[0054] In a particularly suitable embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer or layers are selected from a reduced graphene oxide, graphene, carbon nanotubes, TMDC, single layer metal or single layer metal oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 6 kQ/square (e.g. 0.1 - 6 kQ/square or 0.9-5 kQ/square).

[0055] In an embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer is a reduced graphene oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of ≤ 10 kQ/square (e.g. 0.1 -10 kQ/square or 0.9-5 kQ/square).

[0056] In a particularly suitable embodiment, the continuous 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked heterostructures, wherein the at least one further material layer is a reduced graphene oxide thin film and the stacked heterostructure has a transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of < 6 kQ/square (e.g. 0.1 -6 kQ/square or 0.9-5 kQ/square).

[0057] The continuous 2-dimensional carbon thin films may have an area greater than 0.0001 cm ² . Suitably, the continuous 2-dimensional carbon thin films may have an area greater than 0.001 cm ² . More suitably, the continuous 2-dimensional carbon thin films may have an area greater than 0.01 cm ² . Yet more suitably, continuous 2-dimensional carbon thin films may have an area greater than 0.1 cm ² . Yet more suitably, the continuous 2-dimensional carbon thin films may have an area greater than 1 cm ² .

[0058] Suitably, the continuous 2-dimensional carbon thin films may have an area greater than 10 cm ² . More suitably, the continuous 2-dimensional carbon thin films may have an area greater than 20 cm ² . Even more suitably, the continuous 2-dimensional carbon thin films may have an area greater than 25 cm ² . Yet more suitably, the continuous 2-dimensional carbon thin films may have an area greater than 30 cm ² . Yet more suitably, the continuous 2-dimensional carbon thin films may have an area greater than 35 cm ² . Most suitably, the continuous 2-dimensional carbon thin films may have an area greater than 40 cm ² (e.g. 40-100 cm ² or 40-60 cm ² ).

[0059] The continuous 2-dimensional carbon thin films are substantially defect free. For example, the continuous 2-dimensional carbon thin films may exhibit a sheet resistance of≤850 Ω/square (e.g. 600-800 Ω/square) for a 7.6 cm x 2.5 cm sample and measured via two probe technique across a 2 cm probe distance. In an embodiment, the continuous 2-dimensional carbon thin films are such that the sheet resistance of film remains < 800 Ω/square across a 2.5 cm probe distance. Suitably, the continuous 2-dimensional carbon thin films are such that the sheet resistance of film remains < 800 Ω/square across a 3.4 cm probe distance. More suitably, the continuous 2-dimensional carbon thin films are such that the sheet resistance of film remains < 820 Ω/square across a 4.6 cm probe distance.

[0060] As described hereinbefore, the present invention also provides a composite material comprising a continuous 2-dimensional carbon thin film obtained, directly obtained or obtainable by a process defined herein, wherein the continuous 2-dimensional carbon thin film is as defined in the first aspect of the invention, or has an area divided by thickness ratio (A/T) of greater than 10 ⁸ nm. The further material

[0061] As stated above, the composite materials of the present invention comprise at least one further material. Any suitable further material may be used in the composite material of the present invention.

[0062] In an embodiment, the at least one further material is a planar material with a thickness less than 500 nm, more preferably less than 200nm, and yet more preferably less than 50nm.

[0063] In a particular embodiment, the at least one further material is a 2-dimensional material. Suitably, the at least one further material is a 2-dimensional material that is arranged with the continuous 2D carbon thin film as vertically stacked or in-plane heterostructures.

[0064] In a particular embodiment, the continuous 2D carbon thin film and the at least one further material of the composite material are arranged as vertically stacked or in-plane heterostructure in which the at least one second material is a planar material with a thickness less than 500 nm, more preferably less than 200nm, and yet more preferably less than 50nm.

[0065] In a further embodiment, the at least one further material is selected from the group consisting of graphene, graphene oxide, graphite and graphite oxide, carbon nanotubes, boron nitrides, transition-metal dichalcogenides (TMDCs), single layer metals or metal oxides and single element materials (such as silicene, germanene, stanene and phosphorene).

[0066] In a further embodiment, the at least one further material is selected from the group consisting of graphene, graphene oxide and carbon nanotubes.

[0067] In a further embodiment, the at least one further material is selected from the group consisting of graphene and graphene oxide.

[0068] In a further embodiment, the at least one further material is graphene.

[0069] Transition metal dichalcogenide (TMDC) monolayers are atomically thin semiconductors of the type MX ₂ , with M a transition metal atom (e.g. Mo, W, etc.) and X a chalcogen atom (e.g. S, Se, or Te.). One layer of M atoms is sandwiched between two layers of X atoms.

[0070] In a particular embodiment, the continuous 2D carbon thin film and the at least one further material of the composite material are arranged as vertically stacked or in-plane heterostructures in which the at least one further material is selected from the group consisting of graphene, graphene oxide, graphite and graphite oxide, carbon nanotubes, boron nitrides, transition-metal dichalcogenides (TMDCs), single layer metals or metal oxides and single element materials (such as silicene, germanene, stanene and phosphorene). [0071] In an embodiment, the at least one further material is a planar layer of metal (e.g. copper, silver, gold, chromium, platinum, tungsten, tin or a combination thereof).

[0072] In a particular embodiment, the continuous 2D carbon thin film and the at least one further material of the composite material are arranged as vertically stacked or in-plane heterostructures in which the at least one further material is a planar layer of metal (e.g. copper, silver, gold, chromium, platinum, tungsten, tin or a combination thereof).

[0073] In an embodiment, the at least one further material is a planar layer of metal oxide optionally selected from the groups consisting of copper, zinc, tin, indium oxides or a combination thereof (e.g. a combination of two or three metal oxides, e.g. indium-tin oxides or fluo nated tin oxides). The properties of the metal oxides can be tuned to make them either metal rich or oxygen rich.

[0074] In a particular embodiment, the continuous 2D carbon thin film and the at least one further material of the composite material are arranged as vertically stacked or in-plane heterostructures in which the at least one further material is a planar layer of metal oxide optionally selected from the groups consisting of copper, zinc, tin, indium oxides or a combination thereof (e.g. a combination of two or three metal oxides, e.g. indium-tin oxides or fluohnated tin oxides). The properties of the metal oxides can be tuned to make them either metal rich or oxygen rich.

[0075] It will be appreciated that any suitable combination of layers may be present in the in- plane or vertically stacked heterostructures of the invention. For example, there may be one or more continuous 2-dimensional carbon thin-film layers and one or more layers of the further material.

Preparation of 2-dimensional carbon thin films

[0076] As described hereinbefore, the present invention further provides a process for the preparation of composite material as defined herein, wherein the continuous 2-dimensional carbon thin film is prepared using a process comprising the steps of:

a) providing an organic polymeric thin film that has been prepared by an interfacial polymerisation process, said thin film having a thickness of less than 200 nm; and

b) subjecting the organic polymeric thin film of step a) to a carbonisation process; and wherein the continuous 2-dimensional carbon thin film is then combined with the at least one further material to prepare the composite. [0077] Numerous embodiments and examples of the process for the preparation of the interfacially polymerised polymeric thin film are set out in the applicant's co-pending International Patent Application No. PCT/GB2016/051834.

[0078] The continuous 2-dimensional carbon thin films can be reliably fabricated by preparing a polymeric precursor thin film by interfacial polymerisation and then carbonising the polymeric thin film to remove some or all non-carbon atoms originally present within the thin film. When compared with prior art techniques used for the preparation of 2-dimensional carbon thin films, the process of the invention affords a markedly higher degree of control over the dimensions of the resulting carbon thin film. Specifically, the use of a polymeric precursor thin film prepared by interfacial polymerisation allows the thickness and area of the resulting carbon thin film to be tuned according to the intended application.

[0079] As will be familiar to persons of skill in the art, interfacial polymerisation is a type of step growth polymerization of two reactants occurring at the interface between two immiscible liquid phases (typically aqueous and organic), each containing one of the reactants. At least one reactant has low solubility in the other liquid phase. This ensures a controlled introduction of one reactant into an excess of reactant in the other phase. The reaction rate is typically high, so that reactants diffuse to the interface and combine almost stoichiometrically to form high molecular weight network polymers.

[0080] Persons of skill in the art will be equally familiar with carbonisation processes (e.g. pyrolysis). Carbonisation refers to the conversion of an organic material, including an organic polymeric material, into a carbon residue in which the fraction of carbon is substantially higher than in the starting organic material. The carbonisation process chemically removes some or all non-carbon atoms while also changing the bonding of the carbon atoms within the residue. Carbonisation processes typically include heating the organic material under high temperature in the presence of hydrogen or under vacuum.

[0081] The organic polymeric thin film may be pre-prepared by an interfacial polymerisation process described herein. Alternatively, step a) may comprise the active step of preparing an organic polymeric thin film by an interfacial polymerisation process.

[0082] In an embodiment of the invention, in step a), the organic polymeric thin film is formed by interfacial polymerisation on a supporting substrate. A variety of supporting substrates will be familiar to those of skill in the art, including ceramics, fibrous mats, and woven meshes. Exemplary ceramic supports include porous silicons, porous silicas and porous aluminas. Exemplary fibrous mats include carbon nanofiber networks and assemblies of carbon nanotubes.

[0083] In an embodiment, when step a) comprises the use of a supporting substrate, the organic polymeric thin film is separated from the supporting substrate prior to performing carbonisation step b). The polymeric thin film may be separated from the supporting substrate by any available technique, including peeling, floating using a liquid or gas, or dissolving the supporting substrate in a solvent or acid that leaves the polymeric thin film intact.

[0084] The organic polymeric thin film formed in step a) may be prepared by interfacial polymerisation at the interface of two immiscible liquids. In such embodiments, it may not be necessary to use a supporting substrate. Optionally, during interfacial polymerisation, the two immiscible liquids be agitated (e.g. shaken), thereby increasing the area of interface at which the reaction proceeds. Interfacial polymerisation conducted with agitation may provide a plurality of organic polymeric thin films, the dimensions of which may be such that the plurality of thin films can be considered as a powder.

[0085] Once prepared, the organic polymeric thin film formed in step a) may be freeze dried.

[0086] In an embodiment, in step b) the organic polymeric thin film is placed on a carbonisation support prior to being carbonised. Any suitable carbonisation support may be used. Exemplary supports include silicon, copper and quartz. Following carbonisation, the 2-dimensional carbon thin film may be separated from the carbonisation substrate by any available technique, including peeling, floating using a liquid or gas, or dissolving the carbonisation substrate in a solvent or acid that leaves the 2-dimensional carbon thin film intact.

[0087] The carbonisation step b) may comprise heating the organic polymeric thin film of step a) to a temperature greater than 300 °C in the absence of oxygen.

[0088] Suitably, the carbonisation step b) may comprise heating the organic polymeric thin film of step a) to a temperature greater than 500 °C in the absence of oxygen.

[0089] In a particularly suitable embodiment, the carbonisation step b) may comprise heating the organic polymeric thin film of step a) to a temperature of 500-1500 °C in the absence of oxygen. When high temperatures are used, a ceramic support may be necessary. Suitably, the carbonisation step b) may comprise heating the organic polymeric thin film of step a) to a temperature of 500-1200 °C in the absence of oxygen. More suitably, the carbonisation step b) may comprise heating the organic polymeric thin film of step a) to a temperature of 550-1 150 °C in the absence of oxygen. For example, carbonisation step b) may comprise heating the organic polymeric thin film of step a) to a temperature of 850-1 150 °C in the absence of oxygen.

[0090] Alternatively, the carbonisation step b) comprises heating the organic polymeric thin film of step a) to a temperature greater than 900 °C in the absence of oxygen.

[0091] Alternatively, the carbonisation step b) comprises heating the organic polymeric thin film of step a) to a temperature greater than 1500 °C in the absence of oxygen. Heating to temperatures greater than 1500 °C may, for example, be used when the polymeric thin film is provided as a powder.

[0092] Carbonisation step b) may comprise heating the organic polymeric thin film of step a) to any temperature defined herein in the absence of oxygen for a period of 10 minutes to 6 hours. Suitably, carbonisation step b) may comprise heating the organic polymeric thin film of step a) to any temperature defined herein in the absence of oxygen for a period of 10 minutes to 5 hours. More suitably, carbonisation step b) may comprise heating the organic polymeric thin film of step a) to any temperature defined herein in the absence of oxygen for a period of 10 minutes to 3 hours. Even more suitably, carbonisation step b) may comprise heating the organic polymeric thin film of step a) to any temperature defined herein in the absence of oxygen for a period of 30 minutes to 2 hours.

[0093] In a particularly suitable embodiment, carbonisation step b) comprises heating the organic polymeric thin film of step a) to a temperature of 500-1500 °C in the absence of oxygen at a rate of 2-8 O/minute, and then holding the temperature at 500-1500 °C for 0.2-6 hours (e.g. 0.5-1.5 hours).

[0094] In an embodiment, the carbonisation step be may be conducted under vacuum. Alternatively, the carbonisation step be may comprise heating the organic polymeric thin film of step a) in a reducing atmosphere. Suitably, the reducing atmosphere comprises greater than 5 vol% hydrogen.

[0095] In an embodiment, the carbonisation step is conducted in an inert atmosphere. Suitable inert atmospheres include nitrogen and/or argon. Other gases such as hydrogen, methane and acetylene may also be introduced.

[0096] In an embodiment, the carbonisation step is conducted in an atmosphere of argon or in an atmosphere of argon/hydrogen.

[0097] In a particular embodiment, the carbonisation step is conducted initially under vacuum, followed by a subsequent carbonisation step in a reducing atmosphere. Alternatively, the carbonisation step is conducted initially in a reducing atmosphere, followed by a subsequent carbonisation step under vacuum.

[0098] Alternatively, or additionally, the carbonisation process may be performed by subjecting the organic polymeric thin film to microwave radiation. In such embodiments, the organic polymeric thin film may be supported on quartz (e.g. placed within a quartz crucible).

[0099] In an embodiment, the product of carbonisation step b) is contacted with a reducing agent. Any suitable reducing agent may be used. Suitably the reducing agent is selected from hydrazine, chlorine, fluorine, bromine, iodine, hydrogen chloride, hydrogen bromide and hydrogen iodide. [00100] In an embodiment, the carbonisation step defined herein may be followed by one or more subsequent carbonisation steps to further carbonise the material. For example, the process may comprise a first carbonisation step selected from any of the processes defined hereinbefore and one or more subsequent carbonisation steps (for example a step of contacting the product of the first carbonisation step with a reducing agent as defined hereinabove).

[00101] The organic polymeric thin film of step a) may comprise any polymer that can be suitably prepared by interfacial polymerisation. In an embodiment, the organic polymeric thin film comprises one or more polymers selected from polyamides, polyurea, polypyrrolidines, polyesters, polyurethanes, polyketones, polysiloxanes, poly(amide imide), poly(ether amide) and poly(urea amide).

[00102] Suitably, the organic polymeric thin film prepared in step a) is a network polymer. Network polymers will be readily understood by those of skill in the art as being those polymers which possess a covalently cross-linked 3-dimensional polymeric network (as being distinct from "non-network polymer" (or a "linear" polymer) in which the polymers do not have a covalently cross-linked 3-dimesnional structure).

[00103] In a particular embodiment, the organic polymeric thin film comprises a plurality of 6-membered aryl or heteroaryl moieties (e.g. the monomers of the polymeric thin film comprise one or more 6-membered aryl or heteroaryl moieties).

[00104] In a particular embodiment, the organic polymeric thin film is formed in step a) by interfacial polymerisation of silicon-containing monomers.

[00105] The organic polymeric thin film of step a) may be a polymer having intrinsic microporosity (PIM). PIMs will be understood by those of skill in the art to be those polymers having a continuous network of interconnected intermolecular voids (suitably of less than or equal to 2 nm in size), which forms as a direct consequence of the shape and rigidity (or concavity) of at least a proportion of the component monomers of the network polymer. Consequently, when the organic polymeric thin film of step a) is a PIM, at least one of the reagents used to prepare it possesses concavity. An example of a moiety having concavity which may be used in the preparation of a PIM is shown below:

Suitable PIMs for use as part of the present invention are discussed in WO2013/057492. [00106] In a particular embodiment, the organic polymeric thin film formed in step a) is a polyamide. The polyamide may be prepared by interfacially polymerising of at least one amine- containing reagent with at least one carboxy-containing reagent, thereby providing a network of amido-linked moieties.

[00107] Any suitable concentrations of the at least one amine-containing reagent and the at least one carboxy-containing reagent may be used. In an embodiment, the at least one amine- containing reagent is provided as a first solution containing 0.01 - 16.0 wt% of the at least one amine-containing reagent in a first solvent, and the at least one carboxy-containing reagent is provided as a second solution containing 0.0005- 8.0 wt% of the at least one carboxy-containing reagent in a second solvent. Any suitable first and second solvent may be used. Suitably, the first solvent is water, and the second solvent is organic (e.g. hexane).

[00108] It will be understood that any suitable amine-containing reagent and carboxy- containing reagent may be used. Suitably, the amine-containing reagent and carboxy-containing reagent are not mono-functional (i.e. they contain more than one amine or carboxy functionality each).

[00109] Suitably, the at least one amine-containing reagent contains at least one 6- membered aryl or heteroaryl moiety, and/or the at least one carboxy-containing reagent contains at least one 6-membered aryl or heteroaryl moiety. Accordingly, in an embodiment, the at least one amine-containing reagent is an aryl amine or heteroaryl amine and the at least one carboxy- containing reagent is an aryl or heteroaryl carboxy-containing compound (e.g. an aryl or heteroaryl acyl halide).

[00110] In an embodiment, the amine-containing reagent may contain primary, secondary or tertiary amine groups, or a mixture of each.

[00111] In a particular embodiment, the at least one amine-containing reagent is selected from m-phenylenediamine (MPD), p-phenylenediamine (PPD), piperazine (PIP) or 4- (aminomethyl)piperidine (AMP) and/or the at least one carboxy-containing reagent is an acyl chloride (e.g. 1 ,3,5-benzenetricarbonyl chloride or trimesoyl chloride (TMC)).

[00112] In an embodiment, the first solution contains 0.1 -10.0 wt% of the least one amine- containing reagent. Suitably, the first solution contains 0.1 -5.0 wt% of the least one amine- containing reagent. More suitably, the first solution contains 0.3-4.5 wt% of the least one amine- containing reagent. Even more suitably, the first solution contains 0.1-0.4 wt% of the least one amine-containing reagent.

[00113] In an embodiment, the second solution contains 0.001 -0.6 wt% of the at least one carboxy-containing reagent. Suitably, the second solution contains 0.001 -3.0 wt% of the at least one carboxy-containing reagent. More suitably, the second solution contains 0.001 -0.5 wt% of the at least one carboxy-containing reagent. Even more suitably, the second solution contains 0.0025-0.5 wt% wt% of the at least one carboxy-containing reagent. Yet even more suitably, the second solution contains 0.0025-0.02 wt% of the at least one carboxy-containing reagent. Most suitably, the second solution contains 0.0025-0.01 wt% of the at least one carboxy-containing reagent.

[00114] Particular concentrations of the at least one amine-containing reagent and the at least one carboxy-containing reagent are outlined in the following numbered paragraphs:

a) 0.01 -16.0 wt% of the least one amine-containing reagent and 0.0005- 6.0 wt% of the at least one carboxy-containing reagent.

b) 0.01 -16.0 wt% of the least one amine-containing reagent and 0.0005- 3.0 wt% of the at least one carboxy-containing reagent.

c) 0.01 -16.0 wt% of the least one amine-containing reagent and 0.0005- 0.8 wt% of the at least one carboxy-containing reagent.

d) 0.01 -10.0 wt% of the least one amine-containing reagent and 0.0005-0.5 wt% of the at least one carboxy-containing reagent.

e) 0.01 -10.0 wt% of the least one amine-containing reagent and 0.002-0.5 wt% of the at least one carboxy-containing reagent.

f) 0.01 -5.0 wt% of the least one amine-containing reagent and 0.002-0.5 wt% of the at least one carboxy-containing reagent.

g) 0.01 -5.0 wt% of the least one amine-containing reagent and 0.0025-0.5 wt% of the at least one carboxy-containing reagent.

h) 0.01 -4.5 wt% of the least one amine-containing reagent and 0.0025-0.3 wt% of the at least one carboxy-containing reagent.

i) 0.04-4.5 wt% of the least one amine-containing reagent and 0.0025-0.3 wt% of the at least one carboxy-containing reagent.

j) 0.04-4.5 wt% of the least one amine-containing reagent and 0.0025-0.2 wt% of the at least one carboxy-containing reagent,

k) 0.04-4.0 wt% of the least one amine-containing reagent and 0.0025-0.1 wt% of the at least one carboxy-containing reagent.

I) 0.04-4.0 wt% of the least one amine-containing reagent and 0.0025-0.05 wt% of the at least one carboxy-containing reagent,

m) 0.04-4.0 wt% of the least one amine-containing reagent and 0.0025-0.01 wt% of the at least one carboxy-containing reagent,

n) 0.04-1 .0 wt% of the least one amine-containing reagent and 0.0025-0.01 wt% of the at least one carboxy-containing reagent. [00115] In a particularly suitable embodiment, the first solution contains 0.02-0.3 wt% of the least one amine-containing reagent (e.g. MPD) and the second solution contains 0.02-0.3 wt% of the at least one carboxy-containing reagent (e.g. TMC). Suitably, the first solution contains 0.03-0.2 wt% of the least one amine-containing reagent (e.g. MPD) and the second solution contains 0.03-0.2 wt% of the at least one carboxy-containing reagent (e.g. TMC). More suitably, the first solution contains 0.03-0.1 wt% of the least one amine-containing reagent (e.g. MPD) and the second solution contains 0.03-0.1 wt% of the at least one carboxy-containing reagent (e.g. TMC). Most suitably, the first solution contains 0.03-0.08 wt% of the least one amine- containing reagent (e.g. MPD) and the second solution contains 0.03-0.08 wt% of the at least one carboxy-containing reagent (e.g. TMC).

[00116] Where the concentration of the amine-containing reagent is greater than 1 wt%, and the ratio of amine-containing reagent to carboxy-containing reagent is less than 200 or preferably less than 50, the organic polymeric thin film may have crumpled morphology. This morphology may be preserved during the subsequent carbonisation step.

[00117] Alternatively, where the concentration of the amine-containing reagent is greater than 3 wt%, and the ratio of amine-containing reagent to carboxy-containing reagent is less than 20, and the amine-containing reagent and carboxy-containing reagent are reacted for 0.5-2 minutes (e.g. 1 min) at the interface between an aqueous saturated nanostrand layer and a hexane phase, the organic polymeric thin film may have crumpled morphology. This morphology may be preserved during the subsequent carbonisation step

[00118] In an embodiment, the organic polymeric thin film formed in step a) has a thickness of less than 100 nm. Suitably, the organic polymeric thin film formed in step a) has a thickness of less than 50 nm. More suitably, the organic polymeric thin film formed in step a) has a thickness of less than 40 nm. Even more suitably, the organic polymeric thin film formed in step a) has a thickness of less than 30 nm. Yet even more suitably, the organic polymeric thin film formed in step a) has a thickness of less than 25 nm. Still even more suitably, the organic polymeric thin film formed in step a) has a thickness of less than 20 nm. Still even more suitably, the organic polymeric thin film formed in step a) has a thickness of less than 15 nm. Most suitably, the organic polymeric thin film formed in step a) has a thickness of less than 10 nm

[00119] In an embodiment, following the preparation of the organic polymeric thin film in step a), the organic polymeric thin film is treated with an activating solvent. The use of activating solvents to improve the flux of thin film composite membranes formed by interfacial polymerisation, by contacting the thin film composite membrane with an activating solvent after the interfacial polymerisation reaction, is known in the literature (Jimenez-Solomon M, Bhole Y, and Livingston AG "High Flux Membranes for Organic Solvent Nanofiltration (OSN): Interfacial Polymerisation with Solvent Activation" J. Mem. Sci. 423 (2012) pp 371 -382). The use of such activating solvents may confer advantages upon the resulting 2-dimensional carbon thin film. Suitably, the activating solvent is a polar aprotic solvent. More suitably, the activating solvent is selected form DMF, DMSO, DMAc, THF and methyl THF. Even more suitably, the activating solvent is selected form DMF, DMSO or DMAc.

[00120] In an embodiment, following the preparation of the organic polymeric thin film in step a), the organic polymeric thin film is treated with a compound that induces the formation of charge transfer complexes within aromatic rings that may be present within the organic polymeric thin film. Any suitable compound for inducing the formation of charge transfer complexes may be used. Suitably, the formation of charge transfer complexes is induced by contacting the organic polymeric thin film with iodine vapour under vacuum.

[00121] Following the carbonisation step b), the 2-dimensional carbon thin film is combined with at least one further material, to form a composite material. The at least one further material is chosen from materials formed into layers which are 500nm, 200nm or less than 50nm thickness, from metal films, including those formed from copper, silver, gold, chromium, platinum, tungsten, tin or from 2D materials including, graphene, graphene oxide, graphite and graphite oxide, boron nitrides, transition-metal dichalcogenides (TMDCs), single layer metal oxides, carbon nanotubes, and single element materials such as silicene, germanene, stanene, or phosphorene. The at least one further material may also be a second continuous 2-dimensional carbon thin film material which is different to the other continuous 2-dimensional carbon thin film material present in the composite. The second continuous 2-dimensional carbon thin film material may be formed from a different polymer to the other continuous 2-dimensional carbon thin film material present in the composite (for example, one may be formed from the reduction of a polyamide and the other may be formed from the reduction of a polyester). Alternatively, or in addition, the second continuous 2-dimensional carbon thin film material may have a different physical form to the other continuous 2-dimensional carbon thin film material present in the composite (for example, one may be smooth and the other may be crumpled, irregular or ridged).

[00122] The composite material may be vertically stacked on in-plane stacked.

[00123] The composite material may comprise multiple layers of the 2-dimensional carbon thin film and the at least one further material.

[00124] The composite material may be formed by a process in which the organic polymeric thin film from step (a) and at least one further material are combined before reduction, and the composite material is then subjected to reduction so that both the organic polymeric thin film at least one further material are reduced. [00125] Thus, in another aspect, the present invention provides a process for the preparation of composite material as defined herein, where the material is prepared using a process comprising the steps of:

a) providing an organic polymeric thin film that has been prepared by an interfacial polymerisation process, said thin film having a thickness of less than 200 nm; b) stacking the organic polymeric thin film with at least one further material; and c) subjecting the stack comprising the organic polymeric thin film and the at least one further material to a carbonisation process.

Applications of the composite materials

[00126] As described hereinbefore, the present invention also provides a use of a composite material as defined herein for gas storage and gas separation or as a separation membrane (e.g. liquid separation).

[00127] The composite materials of the invention possess a number of surprising properties that make them ideal candidates for certain applications. The composite materials may have a high surface area and micropore area. Accordingly, they are able to adsorb large quantities of gas (e.g. N ₂ ) at relatively low pressures. Such properties make the composite materials an attractive prospect for a wealth of gas storage and gas separation applications. More specifically, the storage properties of the composite materials may render them useful in medical applications, including drug delivery (wherein the stored species may not be in the gaseous state) and imaging.

[00128] Aside from their storage properties, the specific morphology of the composite materials films makes them interesting candidates within the field of separation science. The use of an organic polymeric thin film precursor of predetermined structure confers a high degree of control on the morphology (e.g. porosity) of the resulting 2-dimensional carbon thin film, hence on the structure of the composite, thereby allowing the preparation of filtration membranes which have tuneable separation characteristics.

[00129] Additionally, owing to their excellent separation properties, strength and controlled morphology the composite materials of the present invention may be used in plastics. Accordingly, the 2-dimensional thin films of the present invention make excellent candidates for use in materials designed for use in, for example, food packaging and condoms.

[00130] Noting the electronic industry's growing interest in 2-D materials, and vertically stacked and in-plane stacked 2-D heterostructures, the conductive and transparent nature of the composite materials renders them an attractive prospect. Hence, in another aspect, the present invention provides a use of a composite material as defined herein in an electronic device. [00131] According to a further aspect of the present invention, there is provided a heterostructure comprising, or formed from, a composite material as defined herein.

[00132] According to a further aspect, the present invention provides an electronic component comprising a composite material or heterostructure as defined herein.

[00133] According to a further aspect, the present invention provides an electronic device comprising a composite material, heterostructure or electronic component as defined herein.

[00134] Examples of devices or components include antenna elements (such as RFID or devices), sensor elements, light emitting diodes, photovoltaic cells, tactile screens (touch panels) or thin film transistors (TFTs).

[00135] According to a further aspect, the present invention provides a use of a composite material as defined herein in an application selected from tissue engineering, bio-imaging (e.g. contrast agents), the polymerase chain reaction, diagnostic devices, drug delivery, bio- microrobotics, blood sensing, electronics (e.g. in transistors, semiconductors, transparent conducting electrodes, frequency multipliers, optoelectronics, Hall effect sensors, organic electronics, spintronics, optical modulators, infrared light sensors and/or photodetectors), membranes for separation, solar cells (e.g. as charge conductors, light collectors and electrodes), in fuel cells, thermoelectric devices, coatings, supercapacitors, batteries, hydrogen storage, in sensors with adsorbed molecules and the piezoelectric effect, wearable devices, magnetic sensors, contaminant removal from gas and liquid streams, water filtration, plasmonics and metamaterials, as lubricants, in radio wave adsorption, in redox devices, as nanoantennas, in sound transducers, as waterproof coatings, as coolant additives, as lubricant additives, as reference materials, in thermal management, as structural materials and as catalysts to speed up the rate of chemical reactions.

[00136] The following numbered clauses are not claims, and instead define particular aspects and embodiments of the claimed invention:

1 . A composite material comprising a continuous 2-dimensional carbon thin film and at least one further material, wherein the continuous 2-dimensional carbon thin film has a thickness of less than 20 nm and an area divided by thickness ratio (A/T) of greater than 10 ¹⁰ nm.

2. The composite material of clause 1 wherein the 2-dimensional carbon thin film and the at least one further material are arranged as vertically stacked or in-plane

heterostructures.

3. The composite material of clause 1 or 2 wherein the at least one further material is a planar material with a thickness less than 500nm. The composite material of any one of the preceding clauses, wherein the at least one further material is a planar material with a thickness less than 250 nm or less than 50nm.

The composite material of any one of the preceding clauses, wherein the at least one further material is a planar layer of metal including gold, silver or chromium, platinum, tungsten, tin.

A composite material of any one of clauses 1 to 3, wherein the at least one further material is a planar layer assembled from carbon nanotubes

The composite material of any one of clauses 1 to 4 wherein the at least one further material is a 2-dimensional material including any of any of graphene, graphene oxide, graphite and graphite oxide, boron nitrides, transition-metal dichalcogenides (TMDCs), single layer metal oxides and single element materials such as silicene, germanene, stanene and phosphorene or a second continuous 2-dimensional carbon thin film (that differs from the other continuous 2-dimensional carbon thin film present in the composite).

The composite material of clauses 1 to 4 wherein the at least one further material is a planar layer of metal oxides optionally selected from the group consisting of copper oxide, zinc oxide, tin oxide, indium oxide and a combination thereof (e.g. two or three metals such as indium-tin oxides, fluorinated tin oxide).

The composite material of clauses 8 wherein the properties of the metal oxide is a metal rich oxide or an oxygen rich oxide.

The composite material of any one of the preceding clauses, wherein the continuous 2- dimensional carbon thin film has a thickness of less than 10 nm.

The composite material of any one of the preceding clauses, wherein the continuous 2- dimensional carbon thin film has a thickness of less than 6 nm.

The composite material of any one of the preceding clauses, wherein at least a portion of the continuous 2-dimensional carbon thin film has a structure corresponding to graphene, graphene oxide or reduced graphene oxide.

The composite material of any preceding clauses, wherein the elemental composition of the thin continuous 2-dimensional carbon thin film is as follows:

85 to 95% carbon, and

2 to 13% oxygen.

The composite material of any preceding clause, wherein the elemental composition of the 2-dimensional carbon thin film is as follows:

88 to 98% carbon,

1 to 6% oxygen, and

0.5 to 6% nitrogen. The composite material of any preceding clause, wherein the 2-dimensional carbon thin film comprises 50-70 atomic% of sp ² carbon atoms.

The composite material of any preceding clause, wherein the 2-dimensional carbon thin film has a light transmittance at a wavelength of 550 nm of≥75% at a film thickness of 2 - 5 nm.

The composite material of any preceding clause wherein the 2-dimensional carbon thin film has a water contact angle value of 55-95°.

The composite material of any preceding clause wherein the continuous 2-dimensional carbon thin film has a sheet resistance of≤ 10 kQ/square

The composite material of any preceding clause, wherein the continuous 2-dimensional carbon thin film has an area greater than 0.001 cm ² .

The composite material of any preceding clause, wherein the 2-dimensional carbon thin film has a BET surface area≥300 m¾ ¹ .

The composite material of any preceding clause, wherein the 2-dimensional carbon thin film has pore volume of≥ 0.15 cm ³ /g.

The composite material of any preceding clause, wherein the 2-dimensional carbon thin film has an average pore width of 0.3-0.7 nm.

The composite material of any preceding clause, wherein the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a

transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of≤ 100 kQ/square.

The composite material of any preceding clause, wherein the continuous 2-dimensional carbon thin film and the at least one further material are arranged as heterostructures (e.g. vertically stacked heterostructures), wherein the heterostructure has a

transmittance of 50-99% at 550 nm at 2-7 nm thickness and a sheet resistance of≤ 20 kQ/square.

The composite material of any preceding clause, wherein the continuous 2-dimensional carbon thin film is a carbonised organic polymeric thin film.

The composite material of any preceding clause, wherein the organic polymeric thin film is a network (as opposed to a linear) polymer.

The composite material of any preceding clause, wherein the organic polymeric thin film has a thickness of less than 100 nm.

The composite material of any preceding clause, wherein the organic polymeric thin film is an interfacially polymerised organic polymeric thin film. The composite material of any preceding clause, wherein the monomers used in the formation of the interfacially polymerised organic polymeric thin film each have a molecular weight of less than 2000 g mol ¹ .

The composite material of any preceding clause, wherein the monomers used in the formation of the interfacially polymerised organic polymeric thin film each have a molecular weight of less than 1000 g mol ^-1 .

The composite material of any preceding clause, wherein the monomers used in the formation of the interfacially polymerised organic polymeric thin film each have a molecular weight of less than 500 g mol ¹ .

A process for the preparation of composite material comprising a 2-dimensional carbon thin film and at least one other material according to any preceding clause, wherein the continuous 2-dimensional carbon thin film is prepared using a process comprising the steps of:

a) providing an organic polymeric thin film formed by an interfacial polymerisation process, said organic polymeric thin film having a thickness of less than 100 nm; and

b) subjecting the organic polymeric thin film of step a) to a carbonisation process; and wherein the continuous 2-dimensional carbon thin film is then combined with the at least one further material to prepare the composite.

A process for the preparation of composite material comprising a 2-dimensional carbon thin film and at least one other material according to any preceding clause, the process comprising the steps of:

a) providing an organic polymeric thin film that has been prepared by an interfacial polymerisation process, said thin film having a thickness of less than 200 nm; and

b) stacking the organic polymeric thin film with at least one further material and c) subjecting the stack comprising the organic polymeric thin film and the at least one further material to a carbonisation process.

The process of clause 32 or 33 wherein, in step a), the organic polymeric thin film is formed by interfacial polymerisation on a supporting substrate.

The process of clause 34 wherein, prior to step b) of clause 32 or step c) of clause 33, the organic polymeric thin film is separated from the supporting substrate.

The process of clause 35 wherein the organic polymeric thin film is separated from the supporting substrate by contacting the supported organic polymeric thin film with a solvent in which the supporting substrate is soluble and the organic polymeric thin film is insoluble. The process of clauses 32 or 33 wherein, in step a), the organic polymeric thin film is prepared by interfacial polymerisation at the interface of two immiscible liquids (e.g. without a supporting substrate).

The process of any of clauses 32 to 37, wherein prior to step b) of clause 32 and step c) of clause 33, the organic polymeric thin film is placed on a carbonisation support.

The process of clause 38 wherein the carbonisation support is selected from silicon, copper, carbon fibre mat, carbon nanotube mat, alumina, or quartz.

The process of any of clauses 32 and 34 to 39 wherein step b) comprises heating the organic polymeric thin film of step a) to a temperature greater than 300 °C in the absence of oxygen.

The process of any of clauses 33 to 40 wherein step c) comprises heating the organic polymeric thin film and at least one further material of step b) to a temperature greater than 300 °C in the absence of oxygen.

The process of any of clauses 32 to 41 , wherein step b) of clause 32 and step c) of clause 33 comprises heating to a temperature greater than 900 °C in the absence of oxygen.

The process of any of clauses 32 to 42, wherein step b) of clause 32 and step c) of clause 33 comprises heating to a temperature greater than 1500 °C in the absence of oxygen.

The process of any of clauses 32 to 43, wherein step b) of clause 32 and step c) of clause 33 comprises heating under vacuum.

The process of any of clauses 32 to 44 wherein, in step b) of clause 32 and step c) of clause 33, the carbonisation process comprises heating in an atmosphere comprising greater than 5 vol% hydrogen.

The process of any of clauses 32 to 45, wherein the process further comprises a step of contacting the product of carbonisation step b) of clause 32 or step c) of clause 33 with a reducing agent.

The process of clause 46 wherein the reducing agent is selected from hydrazine, chlorine, fluorine, bromine, iodine, hydrogen chloride, hydrogen bromide or hydrogen iodide.

The process of any of clauses 32 to 47 wherein the organic polymeric thin film comprises one or more polymers selected from polyamides, polyurea, polypyrrolidines, polyesters, polyurethanes, polyketones, polysiloxanes, poly(amide imide), poly(ether amide) and poly(urea amide).

The process of any of clauses 32 to 48, wherein the organic polymeric thin film is a network polymer. The process of any of clauses 32 to 49 wherein the organic polymeric thin film comprises a plurality of 6-membered aryl or heteroaryl moieties.

The process of any of clauses 32 to 50 wherein the organic polymeric thin film is a polyamide.

The process of any of clauses 32 to 51 , wherein step a) comprises producing an organic polymeric thin film by interfacial polymerisation of reactive monomers.

The process of clause 52, wherein the reactive monomers each have a molecular weight of less than 2000 g mol ¹ .

The process of clause 52, wherein the reactive monomers each have a molecular weight of less than 1000 g mol ¹ .

The process of clause 52, wherein the reactive monomers each have a molecular weight of less than 500 g mol ¹ .

The process of any of clauses 52 to 55, wherein the organic polymeric thin film is a polyamide thin film, and the reactive monomers used in the interfacial polymerisation step a) are at least one amine-containing reagent and at least one carboxy-containing reagent. The process of clause 56, wherein the at least one amine-containing reagent is provided as a first solution containing 0.01 -16.0 wt% of the least one amine-containing reagent in a first solvent, and the at least one carboxy-containing reagent is provided as a second solution containing 0.0005- 8.0 wt% of the at least one carboxy-containing reagent in a second solvent.

The process of clause 57 wherein the first solution contains 0.1 -10 wt% of the least one amine-containing reagent.

The process of clause 57 wherein the first solution contains 0.1 -5 wt% of the least one amine-containing reagent.

The process of clause 57, 58 or 59 wherein the second solution contains 0.001 -3.0 wt% of the at least one carboxy-containing reagent.

The process of clause 57, 58 or 59 wherein the second solution contains 0.0025-0.5 wt% of the at least one carboxy-containing reagent.

The process of clause 57 wherein the amount of amine-containing reagent in the first solution and the amount of carboxy-containing reagent in the second solution are selected from the following:

a) 0.01 -16.0 wt% of the least one amine-containing reagent and 0.0005- 6.0 wt% of the at least one carboxy-containing reagent.

b) 0.01 -16.0 wt% of the least one amine-containing reagent and 0.0005- 3.0 wt% of the at least one carboxy-containing reagent.

c) 0.01 -16.0 wt% of the least one amine-containing reagent and 0.0005- 0.8 wt% of the at least one carboxy-containing reagent. d) 0.01 -10.0 wt% of the least one amine-containing reagent and 0.0005-0.5 wt% of the at least one carboxy-containing reagent.

e) 0.01 -10.0 wt% of the least one amine-containing reagent and 0.002-0.5 wt% of the at least one carboxy-containing reagent.

f) 0.01 -5.0 wt% of the least one amine-containing reagent and 0.002-0.5 wt% of the at least one carboxy-containing reagent.

g) 0.01 -5.0 wt% of the least one amine-containing reagent and 0.0025-0.5 wt% of the at least one carboxy-containing reagent.

h) 0.01 -4.5 wt% of the least one amine-containing reagent and 0.0025-0.3 wt% of the at least one carboxy-containing reagent.

i) 0.04-4.5 wt% of the least one amine-containing reagent and 0.0025-0.3 wt% of the at least one carboxy-containing reagent.

j) 0.04-4.5 wt% of the least one amine-containing reagent and 0.0025-0.2 wt% of the at least one carboxy-containing reagent,

k) 0.04-4.0 wt% of the least one amine-containing reagent and 0.0025-0.1 wt% of the at least one carboxy-containing reagent.

I) 0.04-4.0 wt% of the least one amine-containing reagent and 0.0025-0.05 wt% of the at least one carboxy-containing reagent,

m) 0.04-4.0 wt% of the least one amine-containing reagent and 0.0025-0.01 wt% of the at least one carboxy-containing reagent,

n) 0.04-1 .0 wt% of the least one amine-containing reagent and 0.0025-0.01 wt% of the at least one carboxy-containing reagent.

The process of any of clauses 56 to 62 wherein the at least one amine-containing reagent is an aromatic di- or tri-amine and the at least one carboxy-containing reagent is an aromatic di- or tri- acyl halide.

The process of any of clauses 56 to 63 wherein the at least one amine-containing reagent is selected from m-phenylenediamine, piperazine or 4-(aminomethyl)piperidine.

The process of any of clauses 56 to 64 wherein the at least one amine-containing reagent is m-phenylenediamine.

The process of any of clauses 56 to 65 wherein the at least one carboxy-containing reagent is an acyl chloride (e.g. 1 ,3,5-benzenetricarbonyl chloride).

A composite material obtainable by the process of any of clauses 32 to 66, wherein the continuous 2-dimensional carbon thin film has a thickness of less than 20 nm and an area divided by thickness ratio (A T) of greater than 10 ⁸ nm. A composite material obtainable by the process of any of clauses 32 to 66 wherein the 2- dimensional carbon thin film has a thickness of less than 20 nm and an area divided by thickness ratio (A T) of greater than 10 ¹⁰ nm.

The composite material of clauses 67 or 68, wherein the continuous 2-dimensional carbon thin film has a thickness of less than 10 nm.

The composite material of clauses 67 to 68 wherein the continuous 2-dimensional carbon thin film has a thickness of less than 6 nm.

The composite material of any one of clauses 67 to 70 wherein at least a portion of the continuous 2-dimensional carbon thin film has a structure corresponding to graphite, graphite oxide, reduced graphite oxide, graphene, graphene oxide or reduced graphene oxide.

The composite material of any of clauses 67 to 71 , wherein the elemental composition of the continuous 2-dimensional carbon thin film is as follows:

85 to 95% carbon, and

2 to 13% oxygen.

The composite material of any of clauses 67 to 72, wherein the composite material is as defined in any one of clauses 14 to 24. The composite material of any of clauses 1 to 31 or 67 to 73, wherein there is one, two three, four or five further materials present.

Use of the composite material of any of clauses 1 to 31 and 67 to 74 for gas storage and separation, electrode materials, heterostructures, transistors and electronic components, food packaging, plastics, condoms or as a separation membrane.

A heterostructure comprising a composite material of any of clauses 1 to 31 and 67 to 74. The heterostructure of clause 76 wherein the heterostructure is a vertical or in-plane heterostructure.

An electronic component comprising a composite material of any of clauses 1 to 31 and 67 to 74 or a heterostructure of any of clauses 76 or 77.

An electronic device comprising a composite material of any of clauses 1 to 31 and 67 to 74 or a heterostructure of any of clauses 76 or 77, or an electronic component of clause 78. EXAMPLES

[00137] Examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figure, in which:

Fig. 1 shows the transmittance profile of a vertically stacked composite comprising of reduced graphene oxide and 2DCIPR (Example 1 )

Methods and materials

Chemicals and materials

[00138] Hexane was purchased from VWR International Ltd. Trimesoyl chloride (TMC) 98%, m- phenylenediamine (MPD) flakes >99%, p-phenylenediamine (PPD) flakes >98% piperazine (PIP) ReagentPlus ^® 99%, 4-(Aminomethyl)piperidine (AMP) 96% Poly(methyl methacrylate) (PMMA) (-120,000 g.mol ^"1 ) were purchased from Sigma Aldrich, UK. MPD was purified under vacuum sublimation (~1 x 10 ^~2 mbar) at 75 °C fitted with a cold water trap and used fresh each time. Asymmetric alumina support membranes of diameter 50 mm with pore size between 18 - 150 nm were supplied from Smart Membrane GmBH, Germany and Synkera Technologies, Inc. USA. Graphene oxide (sheets) and Single-Walled Carbon Nanotubes were purchased from Sigma Aldrich, UK. Copper sheets (99.9+%) were purchased from Goodfellow Cambridge Ltd.

Characterisation methods

Carbonisation process to form 2D carbon nanofilm

[00139] Pre-treatment: Purging alumina tube with Ar @ 2L/min for 1 hr followed by the carrier gas @ 2L/min for 1 hr (gas velocity in the sample zone is 45 cm. min ¹ )

Ramp 1 (R1 ): Room temperature (RT) to T _P °C @ 5°C/min and soak at T _p for 0.4 - 5 hr

Ramp 2 (R2): 1 ) RT to 125°C @ 5°C/min and soak for 15 min

2) 125°C to 325°C @ 5°C/min and soak for 5 min

3) 325°C to 425°C @ 2°C/min and soak for 5 min

4) 425°C to 550°C @ 1 °C/min and soak for 5 min

5) 550°C to 600°C @ 0.5°C/min and soak for 2h

Ramp 3 (R3): 1 ) RT to 125°C @ 5°C/min and soak for 15 min

2) 125°C to 375°C @ 5°C/min and soak for 5 min 3) 375°C to 525°C @ 1 °C/min and soak for 5 min

4) 525°C to 600°C @ 0.5°C/min and soak for 2h

Cooling:1 ) Tp°C to 700°C @ 5°C/min (when T _p > 700°C)

2) 700°C to 300°C @ natural cooling

3) 300°C to RT @ natural cooling (swap carrier gas with Ar).

Scanning electron microscopy (SEM)

[00140] Thin films were analysed by high resolution scanning electron microscope (SEM), LEO 1525, Karl Zeiss with an accelerating voltage of 5 kV. A 5 nm thick (measured with attached QCM thickness monitor) coating of chromium was sputtered (Q150T turbo-pumped sputter coater, Quorum Technologies Ltd.) under an Ar atmosphere (2x10-2 mbar) to achieve a minimum conductivity for reliable SEM information.

Atomic force microscopy (AFM) study

[00141] Multimode 4 and 8 (Bruker, CA, USA) atomic force microscope (AFM) equipped with E - type or J - type pizzo scanner was used to measure the thickness and surface roughness of the thin films. Samples were attached onto a magnetic sample disk using double sided adhesive tape. The images were captured under tapping mode or peak tapping mode using PointProbe® Plus silicon-SPM probes (PPP-NCH, NanosensorsTM, Switzerland) with typical tip radius of less than 7 nm. Cantilever resonance frequency was in the range of 204 - 497 kHz with a nominal spring constant of 42 N m-1. A sampling resolution of at least 512 points per line and a speed of 0.2 - 1 Hz were used. Bruker 'NanoScope Analysis beta' or 'Gwyddion 2.38 SPM data visualization and analysis software' was used to process the AFM images. Surface roughness is presented as average roughness (Ra), root-mean-square roughness (Rrms), and peak-to-valley height (Rh), respectively. Surface morphology, roughness parameters and the thickness was estimated from the AFM scans of thin films on different substrates. To measure the thickness from AFM, free-standing thin films were transferred to silicon wafers and dried at room temperature. A scratch was made to expose the wafer surface and allow measurement of the height from the silicon wafer surface to the upper thin film surface. The thickness of the thin film was estimated from the height difference between the silicon and the thin film using a one dimensional statistical function.

[00142] Polymer thin film material fabricated on silicon wafers was studied using atomic force microscopy (AFM). [00143] 2-dimensional carbon thin film material fabricated on silicon wafers was studied using atomic force microscopy (AFM).

UV-vis transmission measurement

[00144] The UV-vis transmittance of the polyamide nanofilms and the derived carbon nanofilms was measured through transmission mode with quartz as substrate. Polymer nanofilm was made either at the nanostrand interface or at the bulk liquid interface and was transferred on to a quartz substrate. Polymer nanofilm was carbonised under diluted gas environment and at different temperature conditions to form 2D carbon with different chemical composition. A high transmittance of more than 90% at 550 nm wavelength was obtained for the carbon nanofilm made from a very low concentration (0.05 wt%) MPD and TMC reacted at the bulk interface and carbonised under Ar/H ₂ at 900 °C for 1 h.

Sheet resistance measurement

[00145] The sheet resistance is a measure of the resistivity per unit thickness of 2D thin film materials and is a special case of resistivity for a uniform sheet thickness. The sheet resistance was measured with four-point-probe method where the probe distance can vary between 0.635 mm and tens of mm. The measured sheet resistance was within few tens of ΚΩ/ .

EXAMPLE 1

Preparation of a vertically stacked composite comprising of araphene oxide and a continuous 2-dimensional carbon thin film layer

Formation of the graphene oxide layer

[00146] Films of graphene oxide were formed on quartz or sapphire slides by drop-casting a 5 mg/ml solution of graphene oxide flakes in water on the slides. The slides were then allowed to dry slowly at room temperature, resulting a film comprising a few layers of graphene oxide.

Reduction of the graphene oxide layer to graphene

[00147] Graphene oxide films on sapphire slides were reduced to graphene via high temperature treatment under hydrogen (argon : hydrogen = 9 : 1 ) for 1 hr at 700 °C. Graphene oxide films on sapphire slides were placed inside a ceramic crucible in an electrical furnace and the temperature was increased at 5 °C per min under the said gas atmosphere. After the reduction process, the furnace was allowed to cool down to room temperature under argon atmosphere. Transfer of the second layer polymer thin film on substrate

[00148] Polyamide thin film was prepared in a beaker by carefully pouring TMC-hexane solution on the surface of aqueous MPD solution. A thin film of thickness about 10 nm with local was formed when reacting with 0.02 wt% MPD and 0.02 wt% TMC at room temperature. The polymer thin film was then picked up on the sapphire slides which had the films of reduced graphene oxide on them.

Carbonisation of second layer polyamide thin film

[00149] Polymer thin films on reduced graphene oxide on sapphire slides were converted to a vertical stack of reduced graphene oxide and continuous 2D carbon thin film via high temperature carbonisation under hydrogen (argon : hydrogen = 9 : 1 ) for 1 hour at 1 100 °C. The sapphire slides were placed inside a ceramic crucible in an electrical furnace and the temperature was increased at 5 °C per min under the said gas atmosphere. After the carbonisation process, the furnace was allowed to cool down to room temperature under argon atmosphere.

[00150] The resulting films of composite material had a sheet resistance of 1 ± 0.5 ΚΩ/ . The transmittance spectrum is shown in Figure 1.

EXAMPLE 2

Preparation of a vertically stacked composite comprising of graphene oxide by spin coating and a continuous 2-dimensional carbon thin film layer

Formation of the graphene oxide layer

[00151] Graphene oxide flakes were suspended in the desired liquid (e.g. water) and suspended by means of sonication/ultrasonication. Chemical additives such as (SDS) can be used to aid in stabilising the suspension to form solutions/suspensions of 0.1 -1 mg.ml- ¹ of graphene oxide. The resulting solutions can be used directly to form the graphene oxide films. A centrifuge can also be used to remove the larger flakes of the suspended material.

[00152] Films of graphene oxide (0.5-1 mg.ml ¹ ) were formed by spin coating a layer of 0.5 ml of the suspension. The coating was done on quartz or sapphire slides. Subsequent layers of the suspensions were coated using the same method to increase the thickness of the coating (1 -10 coatings).

Reduction of the graphene oxide layer to reduced graphene oxide

[00153] Graphene oxide films on quartz or sapphire slides were reduced to reduced graphene oxide via high temperature treatment under hydrogen (argon : hydrogen = 9 : 1 ) for 1 hr at 1 100 °C. Graphene oxide films on sapphire slides were placed inside a ceramic crucible in an electrical furnace and the temperature was increased at 5 °C per min under the said gas atmosphere. After the reduction process, the furnace was allowed to cool down to room temperature under argon atmosphere.

Transfer of the second layer polymer thin film on substrate

[00154] Prior to the deposition of the polyamide thin film, a layer of silver paint was applied to the edges of the reduced graphene oxide films. Polyamide thin film was prepared in a beaker by carefully pouring TMC-hexane solution on the surface of aqueous MPD solution. A thin film of thickness about 10 nm with local was formed when reacting with 0.05 wt% MPD and 0.05 wt% TMC at room temperature. The polymer thin film was then picked up on the quartz or sapphire slides which had the films of reduced graphene oxide on them.

Carbonisation of second layer polyamide thin film

[00155] Polymer thin films on reduced graphene oxide on sapphire slides were converted to a vertical stack of reduced graphene oxide and continuous 2D carbon thin film via high temperature carbonisation under hydrogen (argon : hydrogen = 9 : 1 ) for 1 hour at 1 100 °C. The quartz or sapphire slides were placed inside a ceramic crucible in an electrical furnace and the temperature was increased at 5 °C per min under the said gas atmosphere. After the carbonisation process, the furnace was allowed to cool down to room temperature under argon atmosphere.

[00156] For comparative purposes, a separate sample of the polyamide thin film was also made and reduced without any graphene oxide, which had a sheet resistance of 17.3 + 0.6 kQ/D, and a transmittance of 89.5% at 550 nm.

[00157] Table 1 below shows the properties of vertically stacked composites prepared using 0.5 mg ml ^-1 graphene oxide suspension (1 -10 coatings). Zero sheet resistance means the current did not pass through the sample (or infinite resistance).

Table 1 - properties of vertically stacked composites prepared using 0.5 mq ml ¹ graphene oxide suspension (1 -10 coatings). Graphene oxide concentration = 0.5 mo ml ^'1 , probe spacing = 2 mm, reduction temperature = 1 100 'C, "w/o" denotes without 2-dimensional carbon film, "w/" denotes

with 2-dimensional carbon film.

[00158] Table 2 below shows the properties of vertically stacked composites prepared using 1 mg ml ¹ graphene oxide suspension (1 -10 coatings). Zero sheet resistance means the current did not pass through the sample (or infinite resistance). Table 2 - Properties of vertically stacked composites prepared using 1 mq ml ¹ qraphene oxide suspension (1 -10 coatings). Graphene oxide concentration = 1 mq ml ^'1 , probe spacing = 2 mm, reduction temperature = 1 100 'C, "w/o" denotes without 2-dimensional carbon film, "w/" denotes

with 2-dimensional carbon film.

EXAMPLE 3

Preparation of a vertically stacked composite comprising of Single-walled carbon nanotubes and a continuous 2-dimensional carbon thin film layer

Formation of the SWCNT layer

[00159] SWCNT were suspended in the desired liquid (e.g. water) and suspended by means of sonication/ultrasonication. Chemical additives such as (SDS) can be used to aid in stabilising the suspension to form solutions/suspensions of 0.1 -1 mg.ml ^"1 of SWCNT. The resulting solutions can be used directly to form the SWCNT films. A centrifuge can also be used to remove the larger particles of the suspended material.

[00160] Films of SWCNT (0.5-1 mg.ml ^"1 ) were formed by spin coating a layer of 0.5 ml of the suspension. The coating was done on quartz or sapphire slides. Subsequent layers of the suspensions were coated using the same method to increase the thickness of the coating (1 -4 coatings).

Transfer of the second layer polymer thin film on substrate

[00161] Prior to the deposition of the polyamide thin film, a layer of silver paint was applied to the edges of the reduced graphene oxide films. Polyamide thin film was prepared in a beaker by carefully pouring TMC-hexane solution on the surface of aqueous MPD solution. A thin film of thickness about 10 nm with local was formed when reacting with 0.05 wt% MPD and 0.05 wt% TMC at room temperature. The polymer thin film was then picked up on the quartz or sapphire slides which had the films of SWCNT on top.

Carbonisation of second layer polyamide thin film

[00162] Polymer thin films on SWCNT films on quartz or sapphire slides were converted to a vertical stack of reduced graphene oxide and continuous 2D carbon thin film via high temperature carbonisation under hydrogen (argon : hydrogen = 9 : 1 ) for 1 hour at 1 100 °C. The sapphire slides were placed inside a ceramic crucible in an electrical furnace and the temperature was increased at 5 °C per min under the said gas atmosphere. After the carbonisation process, the furnace was allowed to cool down to room temperature under argon atmosphere.

[00163] For comparative purposes, a separate sample of the polyamide thin film was also made and reduced without any graphene oxide, which had a sheet resistance of 17.3 + 0.6 kQ/D, and a transmittance of 89.5% at 550 nm.

[00164] Table 3 below shows the properties of vertically stacked composites prepared using 0.5 mg ml ^-1 SWCNT suspension (1 -4 coatings). Zero sheet resistance means the current did not pass through the sample (or infinite resistance).

Table 3 - properties of vertically stacked composites prepared using 0.5 mq ml ¹ SWCNT suspension (1 -4 coatings). SWCNT concentration = 0.5 mq ml ^'1 , probe spacing = 2 mm, reduction temperature = 1 l OO'C, "w/o" denotes without 2-dimensional carbon film, "w/" denotes with 2- dimensional carbon film.

EXAMPLE 4

Preparation of a vertically stacked composite comprising of graphene and a continuous 2- dimensional carbon thin film layer before dissolving the metal catalyst

Formation of the graphene film by Chemical Vapour Deposition fCVD)

[00165] Graphene films were prepared on a copper foil using chemical vapour deposition similar to the process described in (Bae et al., Nature Nanotechnology 2010, 5, 574-578). The method is also similar to the method described by patent publication number: US 8470400 B2.

[00166] The copper foil was inserted into a quartz tube which was hosted by a tube furnace. The vacuum was heated to 1060°C where the copper was annealed under a flow of hydrogen (5-10 seem) under vacuum (-0.1 mbar) for 30 minutes. The furnace was then cooled down to 1000°C and methane was introduced into the chamber at a flow of 2.5-5 seem. The flow of methane was allowed for the required deposition time (1 -60 minutes) at a total pressure of ~1 mbar. After the desired time passed, the flow of gases was switched off and the furnace was cooled at either a fast cooling rate {~5°C/s) or a slow cooling rate (-Ο.δΌ/ε). When the furnace reached room temperature, the pressure was increased to atmospheric pressure using Argon. Transfer of the second Polvamide layer onto the substrate

[00167] Polyamide thin film was prepared in a beaker by carefully pouring TMC-hexane solution on the surface of aqueous MPD solution. A thin film of thickness about 10 nm with local was formed when reacting with 0.05 wt% MPD and 0.05 wt% TMC at room temperature. The polymer thin film was then picked up on the copper foil which had been used to synthesize graphene using the process previously outlined.

Carbonisation of second layer polvamide thin film

[00168] Polymer thin films on graphene synthesized on copper were converted to a vertical stack of graphene and continuous 2D carbon thin film via high temperature carbonisation under hydrogen (argon : hydrogen = 9 : 1 ) for 1 hour at 900 °C. The sapphire slides were placed inside a ceramic crucible in an electrical furnace and the temperature was increased at 5 °C per min under the said gas atmosphere. After the carbonisation process, the furnace was allowed to cool down to room temperature under argon atmosphere.

Transfer of the graphene 2D Carbon stack

[00169] The graphene films were transferred to a quartz or sapphire substrate using the method known as wet transfer, described in patent publication number WO 2009129194 A2 and Reina et al., ACS Nano Letters 2009, 9, 30-35. In this method, a layer of a supporting polymer (PMMA) is coated, by spin coating in our case, on top of the copper foil which had been used to create the vertical stack of 2D carbon and graphene.

[00170] The PMMA-2D Carbon-graphene-copper-graphene assembly is then floated on an etching bath (1 M FeCI ₃ ) to dissolve the copper layer, which in turn leads to the destruction of the graphene layer at the bottom of the assembly. The film is let in the etching bath for sufficient time to insure the copper layer completely dissolved. The PMMA-2D Carbon-graphene assembly left is picked up with an appropriate support and transferred into a water bath to remove any residual etchant and then finally transferred onto the required quartz or sapphire substrate.

Removal of the PMMA film

[00171] After allowing the PMMA-2D Carbon-graphene assembly to dry, the PMMA layer was removed by dissolution in an acetone bath.

[00172] Similarly, the PMMA layer was removed by placing the entire assembly in an alumina crucible and heating the assembly up to 600 °C under Argon atmosphere in a tube furnace.

[00173] The process can also be done be performing the steps outlined in paragraph 00146 followed by the steps outlined in paragraph 00147. [00174] The resulting stack of graphene and continuous 2D carbon thin film had a sheet resistance of 400-500 Ω/D. Graphene films which were synthesized and transferred using the outlined methods without the 2D Carbon layer had a sheet resistance of ~2 kQ/D.