Heterostructure between WO3 and metal organic framework-derived BiVO4 nanoleaves for enhanced photoelectrochemical performances

The BiVO4/WO3 heterojunction is one of the most promising photoanode materials for water splitting. Designing BiVO4/WO3 nanostructures that can provide more active sites and suppress charge recombination is essential for improving the photoelectrochemical (PEC) performance. In this study, BiVO4 nanoleaves (NLs) with a high surface area were synthesized on either the surface of WO3 thin films (TF) or on nanorods (NRs) via metal organic framework (MOF)-templated synthesis. The growth of the CAU-17 template and its subsequent reaction with vanadium sources at high temperatures enabled the preparation of BiVO4 NLs with highly uniform compositions. At 1.23 V vs. RHE, the photocurrent densities of BiVO4-NLs/WO3-TF and BiVO4-NLs/WO3-NRs were 1.45 and 2.83 mA/cm2, respectively, where both values are significantly higher than achieved with the bare WO3 counterparts. The high PEC performance is due to the enhanced absorption of visible light by the BiVO4 NLs and efficient charge separation at the type II heterojunction between BiVO4 and WO3. Moreover, the PEC performance of BiVO4-NLs/WO3-NRs demonstrated that the formation of more heterointerfaces via the morphological design of the WO3 bottom layer can further enhance the photoanode efficiency. The MOF-derived synthesis of BiVO4 NLs provides a novel strategy for designing uniform and highly efficient heterostructure photoanodes.