Double-Deck Inverse Opal Photoanodes: Efficient Light Absorption and Charge Separation in Heterojunction

For the first time, double-deck WO 3 /BiVO 4 inverse opal photoanodes (DDIO-WO 3 /BiVO 4 ) 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 WO 3 and BiVO 4, inheriting the periodically ordered macroporous nanostructure. More significantly, the DDIO-WO 3 /BiVO 4 inverse opal photoanodes prepared from the optimized fabrication condition demonstrated a photocurrent that was ∼40 times higher than that of the pure inverse opal WO 3 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/cm 2 at a bias of 1.23 V vs RHE, which profits from improving the poor charge carrier mobility of BiVO 4 by combining it with a WO 3 skeleton and a shrouded bilayer inverse opal structure with a large surface area and good contact with the electrolyte.