Tuning nanocavities of Au@Cu(2)O yolk–shell nanoparticles for highly selective electroreduction of CO(2) to ethanol at low potential

The electrosynthesis of high-value ethanol from carbon dioxide and carbon monoxide addresses the need for the large-scale storage of renewable electricity and reduction of carbon emissions. However, the electrosynthesis of ethanol by the CO(2) reduction reaction (CO(2)RR) has suffered from low selectivity and energy efficiency. Here, we report a catalyst composed of Au nanoparticles in Cu(2)O nanocavities (Au@Cu(2)O) that is very active for CO(2) reduction to ethanol through the confinement of the CO intermediate. The architecture shows tandem catalysis mechanisms in which CO(2) reduction on Au yolks produces CO filling Cu nanocavities, where a sufficiently high CO concentration due to the confinement effect promotes ethanol formation and then results in an ethanol faradaic efficiency of 52.3% at −0.30 V versus the reversible hydrogen electrode (vs. RHE) via regulating the hollow size of the Cu(2)O nanocavities. Such a strategy provides a new way of fabricating various tandem catalysts with high selectivity and efficiency for the CO(2)RR.