In Situ Topotactic Transformation of an Interstitial Alloy for CO Electroreduction

Electrochemical reduction of CO to value-added products holds promise for storage of energy from renewable sources. Copper can convert CO into multi-carbon (C₂₊ ) products during CO electroreduction. However, developing a Cu electrocatalyst with a high selectivity for CO reduction and desirable production rates for C₂₊ products remains challenging. Herein, highly lattice-disordered Cu₃ N with abundant twin structures as a precursor electrocatalyst is examined for CO reduction. Through in situ activation during the CO reduction reaction (CORR) and concomitant release of nitrogen, the obtained metallic Cu° catalyst particles inherit the lattice dislocations present in the parent Cu₃ N lattice. The de-nitrified catalyst delivers an unprecedented C₂₊ Faradaic efficiency of over 90% at a current density of 727 mA cm⁻² in a flow cell system. Using a membrane electrode assembly (MEA) electrolyzer with a solid-state electrolyte (SSE), a 17.4 vol% ethylene stream and liquid streams with concentration of 1.45 m and 230 × 10⁻³ m C₂₊ products at the outlet of the cathode and SSE-containment layer are obtained.