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 Cu^δ+ 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 Cu^δ+, 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.