Asymmetric Bi and S Single Atoms Over Porous Single-Crystal TiO<sub>2</sub> for Efficient CO<sub>2</sub> Photoreduction to Acetic Acid.

Jia, Guangri; Wang, Ying; Sun, Mingzi; Zhang, Yingchuan; Xie, Zhipeng; Cui, Xiaoqiang; Huang, Bolong; Yu, Jimmy C et al. · Adv Mater · 2026

basic_science · Level V

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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<sub>2</sub> to acetic acid is effectively achieved via the triadic synergy of asymmetric Bi (Bi-O<sub>4</sub>), S (S-O<sub>2</sub>), and 3D porous single-crystal TiO<sub>2</sub>, which is realized through a selective extraction process. Specifically, Bi active sites lower the energy barrier for CHO<sup>*</sup> generation and C─C coupling; meanwhile, the S─O structure modulates Bi─O and Ti─O configurations to form strong Lewis base site ((SO<sub>2-</sub>BiO<sub>4</sub>)<sup>δ-</sup>) by constructing a surface sulfate species, thereby accelerating the hydrogenation step in CO<sub>2</sub> reduction. The specifically designed photocatalytic system achieves a high acetic acid production rate of 66.7 µmol g<sup>-1</sup> h<sup>-1</sup> 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.