Tuning nanocavities of Au@Cu₂O yolk-shell nanoparticles for highly selective electroreduction of CO₂ to ethanol at...

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 CO₂ reduction reaction (CO₂RR) has suffered from low selectivity and energy efficiency. Here, we report a catalyst composed of Au nanoparticles in Cu₂O nanocavities (Au@Cu₂O) that is very active for CO₂ reduction to ethanol through the confinement of the CO intermediate. The architecture shows tandem catalysis mechanisms in which CO₂ 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 Cu₂O nanocavities. Such a strategy provides a new way of fabricating various tandem catalysts with high selectivity and efficiency for the CO₂RR.