Indexed on: 14 Nov '18Published on: 14 Nov '18Published in: ACS Applied Materials & Interfaces
The manipulation of interfacial charge separation and transfer is one of primary breakthroughs to improve the water oxidation activity and stability of BiVO4 photoanode. In the present work, CoMoO4-coupled BiVO4 (BiVO4/CoMoO4) film was designed and prepared as photoanode for photoelectrochemical water oxidation. Compared with the bare BiVO4 film, obviously improved photoelectrochemical water oxidation performance was observed on the BiVO4/CoMoO4 film. Specifically, a higher water oxidation photocurrent density of 3.04 mA/cm2 at 1.23 V vs. RHE was achieved on the BiVO4/CoMoO4 photoanode, which is about 220% improvement over bare BiVO4 photoanode (1.34 mA/cm2 at 1.23 V vs. RHE). In addition, the BiVO4/CoMoO4 film photoanode was of better stability and faster hole-to-oxygen kinetics for water oxidation, without significant activity attenuation for 6 hours reaction at 0.65 V vs. RHE. The enhanced water oxidation performance on BiVO4/CoMoO4 film photoanode can be ascribed to the synergistic effect of following factors. (i) In thermodynamics, the photogenerated holes of BiVO4 are directionally transferred to CoMoO4 through their physical coupling interface and valance band potentials matching. (ii) In kinetics, the transferred holes induce the formation of Co3+ active sites on CoMoO4 that could synergistically oxidize H2O to molecular O2 with stable activity.