Unveiling the Proton‐Feeding Effect in Sulfur‐Doped Fe−N−C Single‐Atom Catalyst for Enhanced CO<sub>2</sub> Electroreduction
Shanyong Chen, Xiaoqing Li, Cheng‐Wei Kao, Tao Luo, Kejun Chen, Junwei Fu, Chao Ma, Hongmei Li, Ming Li, Ting‐Shan Chan, Min Liu
Abstract
Abstract Heteroatom‐doping in metal‐nitrogen‐carbon single‐atom catalysts (SACs) is considered a powerful strategy to promote the electrocatalytic CO 2 reduction reaction (CO 2 RR), but the origin of enhanced catalytic activity is still elusive. Here, we disclose that sulfur doping induces an obvious proton‐feeding effect for CO 2 RR. The model SAC catalyst with sulfur doping in the second‐shell of FeN 4 (Fe 1 −NSC) was verified by X‐ray absorption spectroscopy and aberration‐corrected scanning transmission electron microscopy. Fe 1 −NSC exhibits superior CO 2 RR performance compared to sulfur‐free FeN 4 and most reported Fe‐based SACs, with a maximum CO Faradaic efficiency of 98.6 % and turnover frequency of 1197 h −1 . Kinetic analysis and in situ characterizations confirm that sulfur doping accelerates H 2 O activation and feeds sufficient protons for promoting CO 2 conversion to *COOH, which is also corroborated by the theoretical results. This work deepens the understanding of the CO 2 RR mechanism based on SAC catalysts.