Hydrogen-treated BiFeO3 nanoparticles with enhanced photoelectrochemical performance

Abstract

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.