Photoelectrochemical cells with tungsten trioxide/Mo-doped BiVO ₄ bilayers

Mo-doped BiVO ₄ nanocrystals with low bandgap energy were embedded into the surface of WO ₃ film, resulting in WO ₃/BiV _0.95Mo _0.05O ₄ photoanodes, which were tested in photoelectrochemical cells for water splitting. Bilayer photoelectrochemical cells showed enhanced photocurrent density: three times that shown by a cell with a pure WO ₃ photoanode and 1.5 times that of a cell with a WO ₃/BiVO ₄ bilayer photoanode. BiVO ₄ showed poor charge carrier mobility; the performance of photoelectrochemical cells can be improved only when BiVO ₄ is combined with a WO ₃ bottom layer, even after Mo doping and tailoring its transition energies by atomic doping.