Efficient charge separation and transfer of a TaON/BiVO4heterojunction for photoelectrochemical water splitting

Abstract

The separation and transfer of photogenerated electron-hole pairs in semiconductors is the key point for photoelectrochemical (PEC) water splitting. Here, an ideal TaON/BiVO4heterojunction electrode was fabricatedviaa simple hydrothermal method. As BiVO4and TaON were in well contact with each other, high performance TaON/BiVO4heterojunction photoanodes were constructed. The photocurrent of the 2-TaON/BiVO4electrode reached 2.6 mA cm-2at 1.23 Vvs.RHE, which is 1.75 times as that of the bare BiVO4. TaON improves the PEC performance by simultaneously promoting the photo-generated charge separation and surface reaction transfer. When a Co-Pi co-catalyst was integrated onto the surface of the 2-TaON/BiVO4electrode, the surface water oxidation kinetics further improved, and a highly efficient photocurrent density of 3.6 mA cm-2was achieved at 1.23 Vvs.RHE. The largest half-cell solar energy conversion efficiency for Co-Pi/TaON/BiVO4was 1.19% at 0.69 Vvs.RHE, corresponding to 6 times that of bare BiVO4(0.19% at 0.95 Vvs.RHE). This study provides an available strategy to develop photoelectrochemical water splitting of BiVO4-based photoanodes.