Selective Electroreduction of CO<sub>2</sub> and CO to C<sub>2</sub>H<sub>4</sub> by Synergistically Tuning Nanocavities and the Surface Charge of Copper Oxide
Xin Li, Lifen Li, Qineng Xia, Song Hong, Leiduan Hao, Alex W. Robertson, Hao Zhang, Tsz Woon Benedict Lo, Zhenyu Sun
Abstract
Electroreduction of CO2 and CO to high-value chemicals and fuels continues to be a grand challenge. Here, we report synergistic electrolysis of CO2 and CO to C2H4 by concurrently tuning nanocavities and the interface of CuO with a hydrogen evolution inactive metal oxide (ZrO2). The designed CuO@ZrO2 delivers a faradaic efficiency (FE) as high as 54.7 ± 1.1% toward C2H4 formation and a remarkable overall CO2 reduction FE exceeding 84.0% at 250 mA cm–2, significantly outperforming pristine CuO and many recently demonstrated Cu-based catalysts. The composite also exhibits a markedly enhanced FE of converting CO to C2H4, approximately three-fold that of pure CuO. Operando Raman spectroscopy as well as postmortem X-ray photoelectron spectroscopy measurements verify that Cu+ species are well retained in the presence of ZrO2 during CO2 reduction, in stark contrast to the rapid transformation of Cu+ to Cu0 in the catalyst without the metal oxide. Experiments in combination with theoretical calculations further show that the incorporation of ZrO2 substantially decreases the dimerization barriers of adsorbed CO intermediates, thus boosting C–C coupling to produce C2H4.