# Asymmetric Bi and S Single Atoms Over Porous Single‐Crystal TiO2 for Efficient CO2 Photoreduction to Acetic Acid

## TL;DR

A new photocatalytic system efficiently converts CO2 into acetic acid using a combination of bismuth, sulfur, and titanium dioxide structures.

## Contribution

The study introduces a triadic synergy of asymmetric Bi–O4, S–O2, and 3D porous TiO2 for efficient CO2 photoreduction.

## Key findings

- The system achieves a high acetic acid production rate of 66.7 µmol g−1 h−1.
- The selectivity for acetic acid is over 89%.
- The S–O structure forms a strong Lewis base site to accelerate hydrogenation.

## 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 CO2 to acetic acid is effectively achieved via the triadic synergy of asymmetric Bi (Bi–O4), S (S–O2), and 3D porous single‐crystal TiO2, 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 ((SO2–BiO4)δ−) by constructing a surface sulfate species, thereby accelerating the hydrogenation step in CO2 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.

Photocatalytic CO2 to acetic acid is achieved over triadic synergy among asymmetric Bi–O4, S–O2 and 3D porous single‐crystal TiO2, harnessed by a selective extraction process. Particularly, the Bi sites lower the energy barrier for CHO* and C─C coupling, and the structure of S─O regulates Bi─O and Ti─O as a strong Lewis base site ((SO2–BiO4)δ−) to accelerate hydrogenation in CO2 reduction.