BiVO₄-Dotted WO₃ Photoanode with an Inverse Opal Underlayer for Photoelectrochemical Water Splitting

Developing an efficient photoanode is critical for obtaining sustainable hydrogen energy by photoelectrochemical (PEC) water splitting. The performance of a photoanode is usually determined by charge separation and optical absorption efficiency, which can be enhanced by constructing a solid-state junction and applying an inverse opal (IO) structure, respectively. Following such principles, we developed a BiVO4/WO3-IO photoanode with a BiVO4/WO3 junction and an IO layer as an underlayer. Compared with a bare WO3 photoanode with an onset potential of 0.80 VRHE and a photocurrent of 0.13 mA/cm2 at 1.23 VRHE, the BiVO4/WO3-IO photoanode exhibited much better PEC performance with an onset potential of 0.46 VRHE and a photocurrent of 0.94 mA/cm2 at 1.23 VRHE. Such a successful combination of two kinds of modification provides a promising approach to effectively utilize solar energy in visible-light-responsive photoanodes.