Reductive Carbon–Carbon Coupling on Metal Sites Regulates Photocatalytic CO<sub>2</sub> Reduction in Water Using ZnSe Quantum Dots
Zhi‐Kun Xin, Mao‐Yong Huang, Yang Wang, Yu‐Ji Gao, Qing Guo, Xu‐Bing Li, Chen‐Ho Tung, Li‐Zhu Wu
Abstract
Abstract Colloidal quantum dots (QDs) consisting of precious‐metal‐free elements show attractive potentials towards solar‐driven CO 2 reduction. However, the inhibition of hydrogen (H 2 ) production in aqueous solution remains a challenge. Here, we describe the first example of a carbon–carbon (C−C) coupling reaction to block the competing H 2 evolution in photocatalytic CO 2 reduction in water. In a specific system taking ZnSe QDs as photocatalysts, the introduction of furfural can significantly suppress H 2 evolution leading to CO evolution with a rate of ≈5.3 mmol g −1 h −1 and a turnover number (TON) of >7500 under 24 h visible light. Meanwhile, furfural is upgraded to the self‐coupling product with a yield of 99.8 % based on the consumption of furfural. Mechanistic insights show that the reductive furfural coupling reaction occurs on surface Zn‐sites to consume electrons and protons originally used for H 2 production, while the CO formation pathway at surface anion vacancies from CO 2 remains.