Unravelling the C C coupling in CO2 photocatalytic reduction with H2O on Au/TiO2-x: Combination of plasmonic excitation and oxygen vacancy

• DOI: 10.1016/j.apcatb.2021.120147
• Publication Date: 2021-03-18T14:01:47Z
• Authors: Ke Wang; Jiangbo Lu; Ying Lu; Cher Hon Lau; Ying Zheng; Xianfeng Fan
• Keywords: In-situ DRIFTS; Oxygen vacancy; Au/TiO2; Plasmonic photocatalyst; C–C Coupling mechanism; 7. Clean energy; 01 natural sciences; 0104 chemical sciences

Abstract CO2 photocatalytic conversion with H2O is an attractive technology to convert green-house gas into value-added chemicals. However, the main limitation of this process is the low selectivity to products higher than C1. The reaction mechanism, especially C C coupling mechanism, is still ambiguous. In this work, the photocatalytic CO2 reduction with H2O is investigated on oxygen-deficient Au/TiO2-x driven by UV or visible light under continuous flow condition. Notably, an exceptional high selectivity of 20 % towards C2H6 is achieved over 2.76 wt% Au/TiO2-x under plasmonic excitation with the essential involvement of oxygen vacancy (VO). The reaction pathway is reasonably proposed based on a series of in-situ characterization results: the in-situ DRIFTS determined key reaction intermediates, electronic property of Au under excitation state and the critical role of VO. The high selectivity towards C2H6 is explained by the slightly positive-charged Au in Au/TiO2-x under plasmonic excitation and the enhanced *CO stability.