Electrocatalytic CO₂-to-C₂₊ with Ampere-Level Current on Heteroatom-Engineered Copper via Tuning *CO Intermediate Coverage

Abstract

An ampere-level current density of CO₂ electrolysis is critical to realize the industrial production of multicarbon (C₂₊) fuels. However, under such a large current density, the poor CO intermediate (*CO) coverage on the catalyst surface induces the competitive hydrogen evolution reaction, which hinders CO₂ reduction reaction (CO₂RR). Herein, we report reliable amperelevel CO₂-to-C₂₊ electrolysis by heteroatom engineering on Cu catalysts. The Cu-based compounds with heteroatom (N, P, S, O) are electrochemically reduced to heteroatom-derived Cu with significant structural reconstruction under CO₂RR conditions. It is found that N-engineered Cu (N−Cu) catalyst exhibits the best CO₂-to-C₂₊ productivity with a remarkable Faradaic efficiency of 73.7% under −1100 mA cm⁻² and an energy efficiency of 37.2% under −900 mA cm⁻². Particularly, it achieves a C₂₊ partial current density of −909 mA cm⁻² at −1.15 V versus reversible hydrogen electrode, which outperforms most reported Cu-based catalysts. In situ spectroscopy indicates that heteroatom engineering adjusts *CO adsorption on Cu surface and alters the local H proton consumption in solution. Density functional theory studies confirm that the high adsorption strength of *CO on N−Cu results from the depressed HER and promoted *CO adsorption on both bridge and atop sites of Cu, which greatly reduces the energy barrier for C−C coupling.