Double-deck inverse opal photoanodes: Efficient light absorption and charge separation in heterojunction

For the first time, double-deck WO₃/BiVO₄ inverse opal photoanodes (DDIO-WO₃/BiVO₄) were prepared by swelling-shrinking mediated polystyrene template synthetic routes, and the use of the photoanodes in photoelectrochemical cells under simulated solar light was investigated. The double-deck photoanodes represented the compact interface between WO₃ and BiVO₄, inheriting the periodically ordered macroporous nanostructure. More significantly, the DDIO-WO₃/BiVO₄ inverse opal photoanodes prepared from the optimized fabrication condition demonstrated a photocurrent that was ∼40 times higher than that of the pure inverse opal WO₃ photoanodes at a bias of 1.23 V vs RHE. Even without an added catalyst, they produce an outstanding photocurrent density of ∼3.3 mA/cm² at a bias of 1.23 V vs RHE, which profits from improving the poor charge carrier mobility of BiVO₄ by combining it with a WO₃ skeleton and a shrouded bilayer inverse opal structure with a large surface area and good contact with the electrolyte. (Chemical Equation Presented).