Stabilized Cu0 -Cu1+ dual sites in a cyanamide framework for selective CO2 electroreduction to ethylene

Abstract

Electrochemical reduction of carbon dioxide to produce high-value ethylene is often limited by poor selectivity and yield of multi-carbon products. To address this, we propose a cyanamide-coordinated isolated copper framework with both metallic copper (Cu⁰) and charged copper (Cu¹⁺) sites as an efficient electrocatalyst for the reduction of carbon dioxide to ethylene. Our operando electrochemical characterizations and theoretical calculations reveal that copper atoms in the Cu^δ+NCN complex enhance carbon dioxide activation by improving surface carbon monoxide adsorption, while delocalized electrons around copper sites facilitate carbon-carbon coupling by reducing the Gibbs free energy for *CHC formation. This leads to high selectivity for ethylene production. The Cu^δ+NCN catalyst achieves 77.7% selectivity for carbon dioxide to ethylene conversion at a partial current density of 400 milliamperes per square centimeter and demonstrates long-term stability over 80 hours in membrane electrode assembly-based electrolysers. This study provides a strategic approach for designing catalysts for the electrosynthesis of value-added chemicals from carbon dioxide.