Photoelectrochemical (PEC) solar conversion is a green strategy for addressing the energy crisis. In this study, a three-storey nanostructure BiVO4/(RGO/WO3)/W18O49 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 WO3 nanorods (NRs) decorated with BiVO4 nanoparticles (NPs), respectively. The bottom storey is the W18O49 film grown on a pure W substrate. In this novel design, experiments and modeling together demonstrated that the RGO layer and WO3 NRs with a fast carrier mobility can serve as multichannel pathways, sharing and facilitating electron transport from the BiVO4 NPs to the W18O49 film. The high conductivity of W18O49 can further enhance the charge transfer and retard electron-hole recombination, leading to a highly improved PEC efficiency of the BiVO4/WO3 heterojunction. As a result, the as-fabricated three-storey photoanode covered with FeOOH/NiOOH achieves an attractive PEC photocurrent density of 4.66 mA/cm2 at 1.5 V versus Ag/AgCl, which illustrates the promising potential of the three-storey hetero-nanostructure in future photoconversion applications.
Keywords: BiVO4; RGO; WO3; charge transport; multichannel; photoelectrochemical enhancement; three-layer hetero-nanostructure.