Enhanced charge separation and oxidation kinetics of BiVO4 photoanode by double layer structure

Monoclinic bismuth vanadate (BiVO 4 ) is a promising semiconductor for photoelectrochemical water splitting . Here, we developed a facile fabrication of BiVO 4 double layer photoanode on the fluorine-doped tin oxide substrate by electrodeposition . The BiVO 4 double layer photoanode is composed by a dense BiVO 4 film as the inner layer and a nanoporous BiVO 4 film as the outer layer. Compared to the BiVO 4 single layer photoanode, the optimized BiVO 4 double layer photoanode produced a much higher photocurrent of 1.15 mA/cm 2 at 0.6 V vs. Ag/AgCl under AM 1.5G (100 mW/cm 2 ) illumination. The results of the photoelectric conversion kinetics for different samples revealed that the charge separation and oxidation kinetics efficiencies for the BiVO 4 double layer are 47.2% and 51.6% at 0.6 V vs. Ag/AgCl, while the values for BiVO 4 single layer are 32.3% and 35.8%, respectively. The improved photoelectrochemical performance for BiVO 4 double layer is mainly ascribed to the decrease of defect state at the interface after inserting a dense BiVO 4 as an inner layer to prevent the recombination of photogenerated electron-hole pairs.