Promoting CO₂ Electroreduction Over ion-exchange Resin-derived Ni-N-C Catalyst with Sulfur Doping

The utilization of renewable energy for electrocatalytic carbon dioxide reduction reaction (CO₂RR) represents a pivotal technology in sustainable carbon conversion. Single-atom catalysts (SACs) featuring transition metal-nitrogen-carbon (M-N-C) structures have demonstrated exceptional electrocatalytic efficacy in CO₂RR by maximizing atom efficiency. Nevertheless, further investigation is warranted to optimize the catalytic performance of SACs through the selection of suitable carbon sources and supports, as well as the modulation of the microenvironment surrounding individual metal atoms. In this study, a sulfur-doped Ni-N-C catalyst was prepared using a two-step strategy involving metal ion adsorption and thermal decomposition, with porous ion exchange resin serving as the carbon source. Due to the uniform distribution of single atom active centers on the resin-based carbon support and sulfur doping, this catalyst efficiently converts CO₂ into CO with a Faradaic efficiency exceeding 90 % within the range of -0.69~-1.29 V (vs. RHE), reaching a maximum value of 97.7 % (-0.79 V vs. RHE). Theoretical calculations indicate that second-shell sulfur doping effectively promotes coupled transfer of protons and electrons, leading to a significant reduction in Gibbs free energy barriers for CO₂RR intermediate products.