Stabilizing single-atom Pt on BiOBr nanosheets by constructing oxygen vacancies with dramatic CO2 photoreduction activity

Single-atom catalysts (SACs) show great potential in enhancing CO₂ photoreduction activity, thanks to their exceptional atomic efficiency and outstanding catalytic properties. However, the high surface energy of SACs presents a significant challenge, as the single atoms often tend to be aggregated during the synthesis and catalytic processes, thus making them be difficult for efficient and sustainable performance. Herein, we report a strategy to stabilize SACs on photocatalytic materials enabled by creating oxygen vacancy defects on the matrix surface, which allow the single-atom platinum (Pt) uniformly and solidly anchored on BiOBr nanosheets (NSs). The as-synthesized Pt-BiOBr-V_O achieves a dramatic CO₂ photoreduction activity with a CO production rate of 93.5 μmol·g⁻¹·h⁻¹ and 75 % selectivity, outperforming those of most BiOBr-based photocatalysts ever reported. The overall enhanced catalytic behaviors are mainly attributed to the synergistic effect between the Pt single atoms and V_O, which optimizes the electronic structure of BiOBr with improved charge transfer and extended lifetime of photogenerated carriers. Moreover, the created oxygen vacancies could act as the electron absorption centers, thus accelerating the activation of CO₂ and the formation of intermediates. The present work provides new insights on rationally designing highly efficient and stable photocatalysts based on defect engineering for developing sustainable green energy.