Hydrogen-treated BiFeO3 nanoparticles with enhanced photoelectrochemical performance

Enhancing charge separation and collection in semiconducting photoelectrodes is a key issue in the area of photoelectrochemical applications. Herein, we report that the photoelectrochemical performance of BiFeO3 nanoparticles can be significantly enhanced by treatment with hydrogen atmosphere at elevated temperature for different time periods. Compared with pristine BiFeO3 nanoparticles, the hydrogen-treated BiFeO3 nanoparticles showed substantial improvement of intrinsic features from structural, optical and electronic aspects. These hydrogen-treated BiFeO3 nanoparticles exhibit an unexpected red shift, which was attributed to the formation of sub-band-gap states between the conduction and valence bands, resulting from oxygen vacancies due to the hydrogen treatment. However, the highly concentrated defects in BiFeO3 nanoparticles can act as charge annihilation centers, which is not conducive to the separation of photo-generated carriers. The hydrogen-treated BiFeO3 prepared at 300 °C for 15 min exhibited optimal photoelectrochemical performance. More than three times higher photocurrent density was achieved compared with pristine BiFeO3, demonstrating its potential in practical application.