Scalable ampere-level CO2 electroreduction to ethylene enabled by descriptor-guided oxygen affinity engineering

The electroreduction of CO2 to ethylene using renewable electricity offers a sustainable approach for greenhouse gas mitigation. However, the efficient ethylene production is challenged by sluggish C–C coupling and wide product distribution. Guided the energy changes associated with C–C coupling and C–O cleavage as descriptors for ethylene electrosynthesis, we predict and synthesize unsaturated MgO1-x anchored on Cu via an electrochemical-induced phase separation method. Electrochemical evaluation of this catalyst achieves an ethylene Faradaic efficiency of 78.2% at 300 mA cm−2 in a flow cell. Mechanism studies reveal the bifunctionality of MgO1-x. On one side, chemical interaction of MgO1-x with Cu domain stabilizes Cu+ and gives asymmetric Cu+···Cu0 pairs, facilitating the *CO–CHO coupling. On another side, the MgO1-x with high oxygen affinity strengthens the binding with dual-carbon intermediate and promotes the C–O bond dissociation, accelerating ethylene formation. Ultimately, this catalyst delivers 60.7% ethylene selectivity at 25 A in membrane electrode assembly of 100 cm2, equivalent to a C2H4 production rate of 1.1 L h−1. CO2 electroreduction to C2H4 is limited by slow C–C coupling and poor selectivity. Here, the authors report an MgO1-x modified Cu catalyst by descriptor-guided oxygen affinity engineering that achieves selective C2H4 production in large-scale membrane electrode assemblies.