Z-schematic water splitting into H2 and O2 using metal sulfide as a hydrogen-evolving photocatalyst and reduced graphene oxide as a solid-state electron mediator.

Z-schematic water splitting was successfully demonstrated using metal sulfide photocatalysts that were usually unsuitable for water splitting as single particulate photocatalysts due to photocorrosion. When metal sulfide photocatalysts with a p-type semiconductor character as a H2-evolving photocatalyst were combined with reduced graphene oxide-TiO2 composite as an O2-evolving photocatalyst, water splitting into H2 and O2 in a stoichiometric amount proceeded. In this system, photogenerated electrons in the TiO2 with an n-type semiconductor character transferred to the metal sulfide through a reduced graphene oxide to achieve water splitting. Moreover, this system was active for solar water splitting.