Stabilizing *CO intermediate on nitrogen-doped carbon-coated CuxOy derived from metal–organic framework for enhanced electrochemical CO2-to-ethylene†

Abstract

The electrochemical CO₂ reduction reaction (CO₂RR) provides a means for producing ethylene, but its selectivity and stability still need further improvement. Therefore, the development of high-performance electrocatalysts is particularly important. Here, we designed a catalyst Cu_xO_y/CN with a nitrogen-doped carbon (CN) coating, which was prepared by pyrolysis of a nitrogen-containing Cu-based MOF with high porosity, using it as a sacrificial template. For the CO₂RR, the Cu_xO_y/CN catalyst demonstrates very good ethylene selectivity, achieving a faradaic efficiency (FE) of 44% at a current density of 500 mA cm⁻². Impressively, the Cu_xO_y/CN catalyst has a higher partial current density for ethylene in the CO₂RR process, reaching about 220 mA cm⁻², compared with other catalysts recorded in the literature. After the CO₂RR, the Cu_xO_y/CN catalyst exposed the Cu(100) facet and the Cu⁺/Cu⁰ interface, which favored the generation of ethylene. Operando Raman spectroscopy indicates that the CN coating efficiently stabilizes Cu⁺ species under CO₂ electroreduction conditions. Density functional theory (DFT) calculations demonstrate that the CN coating stabilizes *CO intermediates. The CN-coated Cu⁺/Cu⁰ interface sites on the Cu_xO_y/CN catalyst enhance *CO adsorption, increase *CO coverage, promote C–C coupling, and thus improve ethylene selectivity and stability.