Multichannel Charge Transport of a BiVO/(RGO/WO)/WO Three-Storey Anode for Greatly Enhanced Photoelectrochemical Efficiency.

Photoelectrochemical (PEC) solar conversion is a green strategy for addressing the energy crisis. In this study, a three-storey nanostructure BiVO/(RGO/WO)/WO was fabricated as a PEC photoanode and demonstrated a highly enhanced PEC efficiency. The top and middle storeys are a reduced graphene oxide (RGO) layer and WO nanorods (NRs) decorated with BiVO nanoparticles (NPs), respectively. The bottom storey is the WO film grown on a pure W substrate. In this novel design, experiments and modeling together demonstrated that the RGO layer and WO NRs with a fast carrier mobility can serve as multichannel pathways, sharing and facilitating electron transport from the BiVO NPs to the WO film. The high conductivity of WO can further enhance the charge transfer and retard electron-hole recombination, leading to a highly improved PEC efficiency of the BiVO/WO heterojunction. As a result, the as-fabricated three-storey photoanode covered with FeOOH/NiOOH achieves an attractive PEC photocurrent density of 4.66 mA/cm at 1.5 V versus Ag/AgCl, which illustrates the promising potential of the three-storey hetero-nanostructure in future photoconversion applications.