CO2 electroreduction to C2+ products with ampere-level current density over sodium citrate modified Cu2O

Copper-based catalysts hold promise for electrochemical reduction of CO 2 to multi-carbon (C 2+ ) products, but achieving high selectivity and ampere-level current density remains challenging. A key hurdle lies in stabilizing Cu + species under reducing conditions, which are crucial for C-C coupling reaction. Herein, we modified Cu 2 O with sodium citrate through the coordination interaction between Cu atoms and carboxyl group. In situ spectroscopy analysis and theoretical studies revealed that the modification induced electron transfer from Cu 2 O to the citrate anion, stabilizing Cu + species under reduction conditions. Additionally, the presence of sodium citrate facilitated the hydrogenation of *CO to *CHO, with *CHO being more prone to C-C coupling reactions. Thereby, the as-prepared catalyst showed an C 2+ products Faradaic efficiency (FE) of 88.1 % at − 0.9 V vs reversible hydrogen electrode (RHE) with a C 2+ products partial current density ( j C2+ ) of 825.94 mA cm −2 and maintained over 80 % FE at − 1.1 V vs RHE with j C2+ of 1239.92 mA cm −2 . This work suggests that surface modification of Cu 2 O via carboxyl group is an effective strategy for altering the surface electronic structure of Cu 2 O and regulating the C-C coupling pathway, encouraging the exploration of more carboxyl-containing molecules for modifying copper-based catalysts to further enhance electrocatalytic performance.