Lithium Vacancy‐Tuned [CuO4] Sites for Selective CO2 Electroreduction to C2+ Products

Abstract Electrochemical CO 2 reduction to valuable multi‐carbon (C 2+ ) products is attractive but with poor selectivity and activity due to the low‐efficient CC coupling. Herein, a lithium vacancy‐tuned Li 2 CuO 2 with square‐planar [CuO 4 ] layers is developed via an electrochemical delithiation strategy. Density functional theory calculations reveal that the lithium vacancies (V Li ) lead to a shorter distance between adjacent [CuO 4 ] layers and reduce the coordination number of Li + around each Cu, featuring with a lower energy barrier for COCO coupling than pristine Li 2 CuO 2 without V Li . With the V Li percentage of ≈1.6%, the Li 2− x CuO 2 catalyst exhibits a high Faradaic efficiency of 90.6 ± 7.6% for C 2+ at −0.85 V versus reversible hydrogen electrode without iR correction, and an outstanding partial current density of −706 ± 32 mA cm −2 . This work suggests an attractive approach to create controllable alkali metal vacancy‐tuned Cu catalytic sites toward C 2+ products in electrochemical CO 2 reduction.