Patent ID: 8454807

Claim:
A photoelectrochemical cell for decomposing water by irradiation with light so as to produce hydrogen, the cell comprising: a conductive substrate; a first electrode including an optical semiconductor and disposed on a first main surface of the conductive substrate; a second electrode disposed in a region on the first main surface of the conductive substrate where the first electrode is not disposed; an electrolyte containing water and disposed in contact with a surface of the first electrode and a surface of the second electrode; a rib formed to separate a space above the surface of the second electrode from a space above the surface of the first electrode, and to extend along a flow direction of a gas produced on the surface of the second electrode, the rib being formed of a material that allows ions to pass therethrough and prevents a gas from passing therethrough; and a container containing the conductive substrate, the first electrode, the second electrode, the electrolyte, and the rib, wherein the rib covers the surface of the second electrode so as to enclose the space above the surface of the second electrode.