Solar Water Splitting under Neutral Conditions Using Z-Scheme Systems with Mo-Doped BiVO₄ as an O₂-Evolving Photocatalyst

The photocatalytic water-splitting system ideally consists of just photocatalyst powder and water without any additives. Herein, improvement of water-splitting activity under neutral conditions is achieved by applying Mo-doping and cocatalyst-loading to BiVO₄ of an O₂-evolving photocatalyst in a Z-scheme system with Ru-loaded SrTiO₃ doped with Rh as a H₂-evolving photocatalyst and a reduced graphene oxide as an electron mediator. The strategies are based on the idea that the Z-schematic electron migration process in the powdered Z-scheme system with reduced graphene oxide is similar to that in the photoelectrochemical system. Although the reaction condition becomes out of the ideal states, adding Ca(NO₃)₂ and CaCl₂ into the reactant solution further improves the water-splitting activity due to the formation of aggregated photocatalyst particles to boost the electron transfer from Mo-doped BiVO₄ to Ru-loaded SrTiO₃ doped with Rh through the reduced graphene oxide.