Yang Piaoping, Zhao Zhi-Jian, Chang Xiaoxia, Mu Rentao, Zha Shenjun, Zhang Gong, Gong Jinlong
Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China.
Angew Chem Int Ed Engl. 2018 Jun 25;57(26):7724-7728. doi: 10.1002/anie.201801463. Epub 2018 May 17.
Carbon dioxide (CO ) reduction in aqueous solutions is an attractive strategy for carbon capture and utilization. Cuprous oxide (Cu O) is a promising catalyst for CO reduction as it can convert CO into valuable hydrocarbons and suppress the side hydrogen evolution reaction (HER). However, the nature of the active sites in Cu O remains under debate because of the complex surface structure of Cu O under reducing conditions, leading to limited guidance in designing improved Cu O catalysts. This paper describes the functionality of surface-bonded hydroxy groups on partially reduced Cu O(111) for the CO reduction reaction (CO RR) by combined density functional theory (DFT) calculations and experimental studies. We find that the surface hydroxy groups play a crucial role in the CO RR and HER, and a moderate coverage of hydroxy groups is optimal for promotion of the CO RR and suppression of the HER simultaneously. Electronic structure analysis indicates that the charge transfer from hydroxy groups to coordination-unsaturated Cu (Cu ) sites stabilizes surface-adsorbed COOH*, which is a key intermediate during the CO RR. Moreover, the CO RR was evaluated over Cu O octahedral catalysts with {111} facets and different surface coverages of hydroxy groups, which demonstrates that Cu O octahedra with moderate coverage of hydroxy groups can indeed enhance the CO RR and suppress the HER.
水溶液中二氧化碳（CO₂）的还原是一种颇具吸引力的碳捕获与利用策略。氧化亚铜（Cu₂O）是一种很有前景的CO₂还原催化剂，因为它能将CO₂转化为有价值的碳氢化合物，并抑制析氢副反应（HER）。然而，由于还原条件下Cu₂O的表面结构复杂，Cu₂O中活性位点的性质仍存在争议，这导致在设计改进的Cu₂O催化剂时缺乏有效指导。本文通过密度泛函理论（DFT）计算和实验研究相结合的方法，描述了部分还原的Cu₂O(111)表面键合羟基在CO₂还原反应（CO₂RR）中的作用。我们发现表面羟基在CO₂RR和HER中起着关键作用，适度的羟基覆盖度对于同时促进CO₂RR和抑制HER是最佳的。电子结构分析表明，羟基向配位不饱和Cu（Cu⁺）位点的电荷转移稳定了表面吸附的COOH*，这是CO₂RR过程中的关键中间体。此外，还对具有{111}面且羟基表面覆盖度不同的Cu₂O八面体催化剂进行了CO₂RR评估，结果表明适度覆盖羟基的Cu₂O八面体确实可以增强CO₂RR并抑制HER。
