Disruption Symmetric Crystal Structure Favoring Photocatalytic CO2 Reduction: Reduced COOH Formation Energy Barrier on Al Doped CuS/TiO2

• Published in: Advanced functional materials 2024-10, Vol.34 (42), p.n/a
• Main Authors: Wang, Junyan, Zhang, Haoyu, Nian, Yao, Chen, Yiqiang, Cheng, Haolin, Yang, Chen, Han, You, Tan, Xin, Ye, Jinhua, Yu, Tao
• Format: Article
• Language: English
• Subjects: Adsorption; Al doping; Atomic properties; Carbon dioxide; Chemical bonds; Copper sulfides; Crystal structure; Electron states; Free energy; Heat of formation; Molecular structure; Photocatalysis; Photocatalytic CO2 reduction; S vacancy; Symmetry; symmetry breaking; Titanium dioxide
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202406549

How to break the C═O bond and reduce the energy barrier of *COOH formation is the key to triggering the photocatalytic CO2 reduction (PCR) reaction and subsequent proton‐electron processes, which is as important as overcoming high recombination rate of photocarriers. In order to solve this issue, the symmetric structure of CuS/TiO2 is destroyed by S vacancy and Al doping (denoted as Al‐CuS/TiO2), which significantly expands the electron localization range and promotes the cis‐coordination splitting of Cu 3d orbits. The experimental results show that the CO yield selectivity of ≈90.68% and yield of ≈335.68 µmol·g−1·h−1 on Al‐CuS/TiO2. The redistribution of Cu electron states in specific d/s/p orbitals increases the adsorption of CO2 and reduces the reaction energy barrier of *COOH intermediates, while effectively breaking the C═O bond. Doped Al atoms also serve as adsorption sites for H2O molecules, effectively interleaving the competition with photocatalytic CO2 reduction at the Cu sites is effectively staggered. This study provides a new approach to reduce the energy barrier of *COOH formation and to accelerate the photocarrier migration by destroying local symmetry to adjust the crystal structure, which is important for further improving the activity and selectivity of PCR. In this work, the symmetric structure and electron localization range of CuS are successfully adjusted via Al doping and S vacancy. Due to the destruction of CuS symmetry structure, more metal Cu sites are exposed and the electronic structure of the active sites is regulated, which expands the electron localization range and facilitates the adsorption of CO2 and *COOH, which speeds up the photocatalytic CO2 reduction rate.