A robust Ni single-atom catalyst for industrial current and exceptional selectivity in electrochemical CO₂ reduction to CO

While achieving a faradaic efficiency (FE) over 90% in the electroreduction of CO2 to CO with a single transition metal atom anchoring nitrogen-doped carbon (M-N-C) catalyst is indeed notable, the challenge remains in elevating the CO current density to a level suitable for industrial application. Here, we present the synthesis of a hydrophobic Ni single-atom catalyst (Ni-N-HCNs-5h) featuring unsaturated Ni-N coordination and abundant micropores, created by immobilizing nickel atoms on hollow carbon nanospheres. In virtue of the increased accumulation of CO2, inhibited hydrogen evolution reaction (HER), and optimized adsorption strength of intermediates, the Ni-N-HCNs-5h achieves an exceptional CO current density of 577 mA cm(-2) with 96% CO FE at a potential of -1.17 V vs. RHE. Impressively, CO FE over 95% is sustained across a wide range of total current densities, spanning from 100 to 600 mA cm-2. Density functional theory calculations provide insights into reducing the free energy for generating the *COOH intermediate and the suppression of the HER on unsaturated NiN3V sites (where V denotes a coordination vacancy) compared to the NiN4 site. Our work sheds new light on developing M-N-C catalysts with high product selectivity and current densities suitable for industrial-scale CO2 electroreduction to CO.