Abstract
Bismuth vanadate (BiVO4) is a promising semiconductor material for solar energy conversion via photoelectrochemical (PEC) water splitting, whereas its performance is limited by surface recombination due to trapping states. Herein, we developed a new method to passivate the trapping states on BiVO4 surface using ultrathin aluminum oxide (Al2O3) overlayer by atomic layer deposition. The coated ultrathin Al2O3 film on BiVO4 significantly enhanced photocurrent densities of the BiVO4 anodes under standard illumination of AM 1.5 G (100 mW/cm(2)). The electrochemical impedances and photoluminescence spectra were studied to confirm that the improved PEC water splitting performance of BiVO4 was due to the decreased surface recombination state on BiVO4, which effectively enhanced the charge separation.