A 3D macroporous carbon NiCu single-atom catalyst for high current density \(CO_{2}\) electroreduction

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 \(\approx\)90.2% within the current density range of −100 to −500 mA \(cm^{−2}\).