Selective Electroreduction of CO2 and CO to C2H4 by Synergistically Tuning Nanocavities and the Surface Charge of Copper Oxide

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 CO(2 )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 Cu-0 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.