Securing interfacial cationic copper for acidic CO2 reduction to ethylene

Electrocatalytic reduction of CO2 to ethylene utilizing Cu-based catalysts in acidic media demonstrates considerable potential for addressing energy and environmental challenges. However, cationic Cuδ+ is apt to be reduced to Cu0 under the harsh acidic CO2 reduction conditions. Here we show that the interface of yttrium-doped ZrO2 and CuO (YSZ/CuO) can stabilize cationic Cuδ+, preventing its over-reduction even at high applied potentials. The YSZ/CuO catalyst achieves a faradaic efficiency of 68.7% and a partial current density of 545.0 mA·cm–2 for ethylene formation in acidic media (pH = 2). In-situ characterization and theoretical calculations indicate that the abundant oxygen vacancies in YSZ promote the initial formation of interfacial oxygen from CuO rather than the support. The interfacial oxygen derived from CuO offers a high charge density of Cu, facilitated by electron transfer from Zr/Y to Cu, leading to a shortened Cu-O bond and enhances stabilization against reduction. This interface engineering strategy not only protects cationic metals under reducing and acidic conditions but also provides valuable insights applicable across heterogeneous catalysis. Electrochemical CO2 reduction on copper-based catalysts under acidic conditions offers a promising solution to energy and environmental issues. Our study demonstrates that the yttrium-doped ZrO2/CuO interface stabilizes Cu+ under harsh conditions, thereby enabling high selectivity toward ethylene.