▎ 摘　　要

A powdered Z-scheme system for the photocatalytic water splitting reaction under visible light irradiation was successfully demonstrated utilizing a combination of a metal-complex catalyst, reduced graphene oxide (RGO), and semiconductor photocatalysts. A Ru-complex electrocatalyst, [Ru (2,2'-bipyridine)(4,4'-diphosphonate-2,2'-bipyridine)(CO)(2)](2+), linked with SrTiO3 : Rh (Rh: 4 at%) as a H+ reduction photocatalyst was coupled with BiVO4 as a water oxidation photocatalyst and RGO as a solid-state electron mediator. H-2 and O-2 evolved stoichiometrically under visible light irradiation (lambda > 420 nm) and the turnover number for the Ru-complex was calculated to be 450 after 8.5 h of irradiation time, which indicates that this Z-scheme system splits water photocatalytically and the Ru-complex functions as an efficient cocatalyst for hydrogen evolution by water splitting.