Triggering Synergy between p-Type Sputter-Deposited FeMnO_x or FeNiO_x 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 BiVO 4, 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 BiVO 4 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 FeMnO x and FeNiO x hole-selective cocatalysts over pure and W-doped BiVO 4 particles which led to a remarkable improvement in photocatalytic O 2 evolution. As compared with the pristine BiVO 4 (93 μmol), the photocatalytic O 2 evolution enhanced to 143 and 181 μmol per 25 mg of samples upon loading FeMnO x cocatalyst over pure and W-doped BiVO 4, 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 FeMnO x exhibits an intense built-in electric field compared with FeNiO x, thus resulting in better O 2 evolution. Our study offers a facile way to boost the photocatalytic activity of BiVO 4 by uniformly loading bimetallic cocatalysts as a hole scavenger on the material surface via DC magnetron sputtering.