Solar hydrogen production. Significant effect of Na2CO3 addition on water splitting using simple oxide semiconductor photocatalysts

Recent progress in photocatalytic decomposition of water to H-2 and O-2 usi ng simple oxide semiconductor catalysts has been reviewed. Addition of Na2C O3 to Pt/TiO2 suspension in water enhanced the stoichiometric decomposition significantly. This Na2CO3 addition method has been proved to be very usef ul to accelerate water splitting over various kinds of oxide semiconductor photocatalysts. The role of CO32- anion on the acceleration of water splitt ing was clarified. Finally, it was firstly demonstrated in the world that w ater was decomposed efficiently and stoichiometrically to H-2 and O-2 using a 3 wt% NiOx/TiO2 photocatalyst under real solar light irradiation in Tsuk uba, Japan by this Na2CO3 addition method.