A 3D Macroporous Carbon NiCu Single‐Atom Catalyst for High Current Density CO₂ Electroreduction

Abstract Transition metal and nitrogen co‐decorated carbon materials are promising platforms for CO 2 electroreduction. A hard‐template 2‐step pyrolysis method is proposed for the fabrication of highly dispersed Ni and Cu atomic active sites on a 3D macroporous carbon matrix. The pyrrolic N‐type Ni−N x sites serve as dominant active sites toward selective CO 2 electroreduction to CO. The incorporation of Cu alters the distribution of N species and simultaneously optimizes the electronic state and geometric structure of the Ni−N x moiety, thereby improving its adsorption and activation capacity for CO 2 . Moreover, the isolated Cu atomic sites enhance the resistance of corresponding gas‐diffusion electrodes against electrolyte flooding. The optimal catalyst 3D NiCu‐69 achieves nearly exclusive production of CO with a Faraday efficiency (FE CO ) of 98% at a current density of −700 mA cm −2 in a CO 2 ‐gas‐fed flow‐through electrolyzer and delivers a CO production rate of 1363 mol(m 2 s) −1 , which is exceeding most reported electrocatalysts. The FE CO remained as high as 94% after electrolyzing at a current density of −100 mA cm −2 for 22 h. 3D NiCu‐69 exhibits a favorable performance in both acidic and neutral conditions, with a high FE CO of ≈90.2% within the current density range of −100 to −500 mA cm −2 .