Surface defect and lattice engineering of Bi5O7Br ultrathin nanosheets for efficient photocatalysis

The effective separation and migration of photogenerated charge carriers in bulk and on the surface of photocatalysts will significantly promote photocatalytic efficiency. However, the synchronous regulation of photocharges on both counts is challenging. Herein, the simultaneous separation of bulk and surface photocharges is conducted to enhance photocatalytic activity by coupling the surface defects and lattice engineering of bismuth oxybromide. The depth-modulated Bi5O7Br ultrathin nanosheets with an abundance of bismuth in the crystal structure increased the internal electric field, which propelled the separation and migration of photocharges from bulk to the surface. Creation of oxygen vacancies (OVs) on the nanosheet surface forms local electric fields, which can stimulate the migration of charges to active sites on the catalyst surface. Therefore, the OV-assembled Bi5O7Br nanosheets demonstrated enhanced photocatalytic degradation efficiency under simulated solar-light illumination. This study proved the possibility of charge governing via electric field modulation based on an integrated strategy.