Oxygen-Bridged Cu Binuclear Sites for Efficient Electrocatalytic CO<sub>2</sub> Reduction to Ethanol at Ultralow Overpotential
Fengfei Xu, Biao Feng, Zhen Shen, Yiqun Chen, Jiao Liu, Yan Zhang, Jingyi Tian, Junru Zhang, Xizhang Wang, Lijun Yang, Qiang Wu, Zheng Hu
Abstract
Electrocatalytic CO 2 reduction (CO 2 RR) to alcohols offers a promising strategy for converting waste CO 2 into valuable fuels/chemicals but usually requires large overpotentials. Herein, we report a catalyst comprising unique oxygen-bridged Cu binuclear sites (CuOCu-N 4 ) with a Cu···Cu distance of 3.0–3.1 Å and concomitant conventional Cu–N 4 mononuclear sites on hierarchical nitrogen-doped carbon nanocages (hNCNCs). The catalyst exhibits a state-of-the-art low overpotential of 0.19 V (versus reversible hydrogen electrode) for ethanol and an outstanding ethanol Faradaic efficiency of 56.3% at an ultralow potential of −0.30 V, with high-stable Cu active-site structures during the CO 2 RR as confirmed by operando X-ray adsorption fine structure characterization. Theoretical simulations reveal that CuOCu-N 4 binuclear sites greatly enhance the C–C coupling at low potentials, while Cu-N 4 mononuclear sites and the hNCNC support increase the local CO concentration and ethanol production on CuOCu-N 4 . This study provides a convenient approach to advanced Cu binuclear site catalysts for CO 2 RR to ethanol with a deep understanding of the mechanism.