Enhancement of photocatalytic ammonia production over BiOBr nanosheets with photo-assembled Au cocatalysts

Noble metal loading has emerged as a promising approach to improve the activity of photocatalysts by promoting charge separation. However, the enhancement effect is highly dependent on the size of metal cocatalysts and interface parameters at nanoscales. Herein, a solid-phase light-driven process was conducted to construct ultrasmall Au nanococataysts from atomically dispersed Au clusters on BiOBr nanosheets. Based on the experiments of N2 photoreduction, the solid-state reconstruction of Au cocatalysts with the assistance of light significantly improved their activity for NH3 production. The photo-assembled BiOBr/Au-CP with both Au culsters and nanoparticles exhibited a striking NH3 evolution rate, superior to BiOBr/Au-C with only atomically dispersed Au and traditional BiOBr/Au-T with only larger photodeposited Au nanoparticles. This study provides a facile bottom-up strategy to precisely control the site activity around the semiconductor/cocatalyst interface at the atomic level.