In Situ Topotactic Transformation of an Interstitial Alloy for CO Electroreduction

Abstract Electrochemical reduction of CO to value‐added products holds promise for storage of energy from renewable sources. Copper can convert CO into multi‐carbon (C 2+ ) products during CO electroreduction. However, developing a Cu electrocatalyst with a high selectivity for CO reduction and desirable production rates for C 2+ products remains challenging. Herein, highly lattice‐disordered Cu 3 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 Cu 3 N lattice. The de‐nitrified catalyst delivers an unprecedented C 2+ 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 C 2+ products at the outlet of the cathode and SSE‐containment layer are obtained.