Akihide Iwase

The construction of Z‐scheme systems is an efficient strategy to realize water splitting under visible light irradiation. In particular, various photocatalysts can be employed for Z‐scheme systems when a reduced graphene oxide (RGO) is used as an electron mediator. Herein, a simple 1‐step process for the preparation of RGO‐(CoO x /BiVO 4 ) composites is developed. In the developed preparation method, Co ions are oxidized to CoO x by photogenerated holes in BiVO 4 accompanied by simultaneous reduction of GO to RGO by photoexcited electrons. The developed preparation method is simpler than a conventional method that contains loading with CoO x by impregnation and subsequent incorporation of RGO by photocatalytic reduction. Z‐schematic water splitting under visible light irradiation proceeds when RGO‐(CoO x /BiVO 4 ) prepared by the 1‐step process is combined with Pt/(CuGa) 0.5 ZnS 2 . Moreover, the developed method is also able to be applied to the preparation of RGO‐(FeO x /BiVO 4 ) composites.