Stress-induced BiVO4 photoanode for enhanced photoelectrochemical performance

BiVO4 is a promising and environmental-benign photoanode material. However, the photoelectrochemical properties of BiVO4 are confined to its low charge separation efficiency. Herein, we have developed a simple method to introduce stress into the BiVO4 photoanode via the change of the unit cell volume of VO2 near the phase transition temperature. In this way, the crystal structure of BiVO4 is caused to be distorted and thus improve the photoelectrochemical properties of the BiVO4 photoanode, making the surface photopotential of the BiVO4-V photoanode nearly double that of the bare BiVO4 photoanode. At room temperature, the photocurrent density of the BiVO4-V photoanode is 2.35 times that of the BiVO4 photoanode. Intriguingly, at 85 °C, the photocurrent density of the BiVO4-V photoanode is as high as 6.8 times that of the BiVO4 photoanode. Moreover, the photocurrent density of the BiVO4-V photoanode could reach 80% of the theoretical photocurrent density of the BiVO4 photoanode at 85 °C in the presence of the sacrificial agent Na2SO3. This work illustrates a new stress engineering strategy to improve the photoelectrochemical properties of BiVO4 photoanodes and is expected to be applicable to other semiconductor photoanodes.