Triggering Synergy between p-Type Sputter-Deposited FeMnOx or FeNiOx and W-Doped BiVO4 for Enhanced Oxygen Evolution

Engineering the photogenerated charge transfer through the solid–liquid interface is a key factor in boosting the solar energy conversion device performance, particularly, for BiVO4, which suffers recombination due to its short hole diffusion length and faster e–/h+ recombination. Site-selective cocatalysts have a strong potential to scavenge holes from the BiVO4 surface. However, uniform incorporation of the cocatalyst on the semiconductor surface is also challenging. This study describes simple one-step radio frequency (RF) magnetron sputtering deposition of bimetallic p-type FeMnOx and FeNiOx hole-selective cocatalysts over pure and W-doped BiVO4 particles which led to a remarkable improvement in photocatalytic O2 evolution. As compared with the pristine BiVO4 (93 μmol), the photocatalytic O2 evolution enhanced to 143 and 181 μmol per 25 mg of samples upon loading FeMnOx cocatalyst over pure and W-doped BiVO4, respectively, under solar irradiation conditions (AM 1.5 G) which were also higher than the previous literature. The enhancement in the photoactivity was attributed to the formation of controlled and site-selective p–n junctions that led to the development of built-in electric field, thereby increasing the charge transfer and suppressing the charge recombination. The band alignment was studied by the classical band bending model, which suggested FeMnOx exhibits an intense built-in electric field compared with FeNiOx, thus resulting in better O2 evolution. Our study offers a facile way to boost the photocatalytic activity of BiVO4 by uniformly loading bimetallic cocatalysts as a hole scavenger on the material surface via DC magnetron sputtering.