Multichannel Charge Transport of a BiVO₄/(RGO/WO₃)/W₁₈O₄₉ 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 4 /(RGO/WO 3 )/W 18 O 49 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 3 nanorods (NRs) decorated with BiVO 4 nanoparticles (NPs), respectively. The bottom storey is the W 18 O 49 film grown on a pure W substrate. In this novel design, experiments and modeling together demonstrated that the RGO layer and WO 3 NRs with a fast carrier mobility can serve as multichannel pathways, sharing and facilitating electron transport from the BiVO 4 NPs to the W 18 O 49 film. The high conductivity of W 18 O 49 can further enhance the charge transfer and retard electron–hole recombination, leading to a highly improved PEC efficiency of the BiVO 4 /WO 3 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 2 at 1.5 V versus Ag/AgCl, which illustrates the promising potential of the three-storey hetero-nanostructure in future photoconversion applications.