Asymmetric Bi and S Single Atoms Over Porous Single‐Crystal TiO 2 for Efficient CO 2 Photoreduction to Acetic Acid

ABSTRACT Regulating multi‐step photocatalytic conversion of molecules remains challenging, primarily due to the complex interplays among light absorption, reactant binding, and charge separation and transfer processes. Here, the photocatalytic conversion of CO 2 to acetic acid is effectively achieved via the triadic synergy of asymmetric Bi (Bi–O 4 ), S (S–O 2 ), and 3D porous single‐crystal TiO 2 , which is realized through a selective extraction process. Specifically, Bi active sites lower the energy barrier for CHO * generation and C─C coupling; meanwhile, the S─O structure modulates Bi─O and Ti─O configurations to form strong Lewis base site ((SO 2– BiO 4 ) δ− ) by constructing a surface sulfate species, thereby accelerating the hydrogenation step in CO 2 reduction. The specifically designed photocatalytic system achieves a high acetic acid production rate of 66.7 µmol g −1 h −1 with over 89% selectivity. This design underscores the significance of engineering synergistic active sites and charge transfer to enhance photocatalytic conversion efficiency, offering valuable insight into the structure‐activity relationship for developing high‐performance photocatalysts.