Abstract: Provided are a photocatalyst electrode, an artificial photosynthesis module, and an artificial photosynthesis device that have low electrical resistance, even in a case where the area is increased, in a case where a transparent conductive layer is used. The photocatalyst electrode is a photocatalyst electrode that has a substrate, a transparent conductive layer, a photocatalyst layer, and a linear metal electrical conductor, and splits water with light to produce a gas. The substrate, the transparent conductive layer, and the photocatalyst layer are laminated in this order, and the linear metal electrical conductor is in contact with the transparent conductive layer. The artificial photosynthesis module has the oxygen evolution electrode that splits the water with the light to produce oxygen, and a hydrogen evolution electrode that splits the water with the light to produce hydrogen.

Abstract: Disclosed are metal nitride photocatalyst particles and/or metal oxynitride photocatalyst particles having high dispersibility. The metal nitride photocatalyst particles and/or metal oxynitride photocatalyst particles having high dispersibility can be obtained by containing metal nitride photocatalyst particles and/or metal oxynitride photocatalyst particles, which are capable of splitting water under visible light irradiation, and a phosphoric acid polymer that is adsorbed on the surface of the particles. Further, because these particles have high photocatalytic activity under visible light irradiation, splitting water by using these particles can generate hydrogen and/or oxygen with high efficiency.