《ACS Catal.》: Constructing Charge-Asymmetrical Au Pair Sites for Photoreduction of Air-Concentration CO₂ into CH₃COOH

Qinyuan Hu,⁺ Jiawei Xie,⁺ Fangming Zhao,⁺ Zhixing Zhang, Yanglu Yu, Xiaodong Li,* Wensheng Yan, Jun Hu, Junfa Zhu, Yang Pan, Meng Zhou,* Yuming Dong,* and Xingchen Jiao*

The photoreduction of carbon dioxide (CO₂) into C₂ products faces a significant C–C coupling challenge. Charge asymmetry active sites constructed through loading engineering can effectively promote C–C coupling. Herein, we propose that the Au atom pairs with an asymmetric charge distribution in the ZnNb₂O₆ nanosheets trigger the acetic acid (CH₃COOH) formation for photoreduction of air-concentration CO₂. Density functional theory calculations indicate that the Au-ZnNb₂O₆ nanosheet slab has the potential to tailor CO₂-to-CH₃COOH pathway own to the presence of Au atom pairs. In situ Fourier transform infrared spectra detect the *COCOH intermediate, confirming the occurrence of C–C coupling, while quasi in situ X-ray photoelectron spectroscopy verifies the Au atoms functioned as the active sites. The TA spectra revealed the electron transfer process from ZnNb₂O₆ nanosheets to Au particles. Accordingly, the Au-ZnNb₂O₆ nanosheets achieve a CH₃COOH formation rate of 2.19 μmol g^–1 h^–1 and a selectivity of 50.5%, whereas pristine ZnNb₂O₆ nanosheets produce only CO products.

Figure 1. Schematic illustration for photoreduction of CO₂ into C₂ products over the charge asymmetrical Au sites.