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 (VLi ) 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 VLi . With the VLi percentage of ≈1.6%, the Li2- x CuO2 catalyst exhibits a high Faradaic efficiency of 90.6± 7.6% for C2+ at -0.85V 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.