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

Abstract

Electrochemical CO₂ reduction to valuable multi-carbon (C₂₊ ) products is attractive but with poor selectivity and activity due to the low-efficient CC coupling. Herein, a lithium vacancy-tuned Li₂ CuO₂ with square-planar [CuO₄ ] 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 [CuO₄ ] layers and reduce the coordination number of Li⁺ around each Cu, featuring with a lower energy barrier for COCO coupling than pristine Li₂ CuO₂ without V_Li . With the V_Li percentage of ≈1.6%, the Li_2- _x CuO₂ catalyst exhibits a high Faradaic efficiency of 90.6 ± 7.6% for C₂₊ 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 C₂₊ products in electrochemical CO₂ reduction.