To provide a water electrolysis apparatus of a novel structure, which facilitates decomposition reaction of water and is sufficient for practical use.
A water electrolysis apparatus 200 includes: a casing 3; a working electrode 250 and a counter electrode 60 on which an optical semiconductor catalyst is carried; an electrolytic solution filled inside the casing 3; and an electric current applying part 270 that applies electric current between the working electrode and the counter electrode. The interior of the casing is divided into an oxygen-generating chamber 21 and a hydrogen-generating chamber 31 by an electrolyte membrane 70, a light-receiving part 211 is formed on the oxygen-generating chamber, the working electrode is disposed facing the light-receiving part, an optical semiconductor catalyst layer 251 is formed on a lateral side of the light-receiving part of the working electrode, the counter electrode is disposed in the hydrogen-generating chamber, an electrolytic solution passage 260 is formed in casings 210 and 220 composing the oxygen-generating chamber and/or the working electrode, and a concave part 213 is formed via the electrolytic solution passage, thereby enabling the electrolytic solution inside the oxygen-generating chamber to contact with both the optical semiconductor catalyst layer and the electrolyte membrane.
OKADA MASANORI
Tomoko Nakamura
Seiji Kimura