Preparation of WO₃, BiVO₄ and reduced graphene oxide composite thin films and their photoelectrochemical performance

Various thin films for photoelectrochemical (PEC) water splitting were prepared and their PEC performance was tested. The precursor solutions for WO₃ and BiVO₄ photocatalysts were synthesized by solution processes, and the graphene oxide (GO) was prepared by Tour's method and was calcined and converted to reduced graphene oxide (rGO). The composite photocatalyst thin films of WO₃, BiVO₄, WO₃/BiVO₄ and WO₃/BiVO₄-rGO were prepared on fluorine doped tin oxide glass by spin coating and calcination processes and the PEC performances were analyzed for those photocatalyst layers. The controlled WO₃/BiVO₄ heterojunction layer showed better PEC performance than the WO₃ or BiVO₄ single layer by the combined effects of photocatalysts. The WO₃/BiVO₄-rGO film with the optimum concentration of rGO showed a noticeable increase in photocurrent density because of the increased electrical conductivity by rGO and reduced recombination rate in BiVO₄ layer.