Optimizing the Electrocatalytic Selectivity of Carbon Dioxide Reduction Reaction by Regulating the Electronic Structure of Single-Atom M-N-C Materials

Abstract

Electrochemical carbon dioxide reduction reaction (CO₂RR) is an efficient strategy to relieve global environmental and energy issues by converting excess CO₂ from the atmosphere to value-added products. Atomically dispersed metal-nitrogen-doped carbon (M-N-C) materials are superior catalysts for electrocatalytic CO₂RR because of the 100% atomic utilization, unsaturated coordination configuration, relatively uniform active sites, and well-defined and adjustable structure of active centers. However, the electrochemical CO₂RR is a great challenge due to the process involving proton-coupled multi-electron transfer with a high energy barrier, which leads to unsatisfactory selectivity to the targeted product, especially for C2 products (e.g., C₂H₄ and C₂H₅OH). Here, the authors systematically summarize effective means, including reasonable selection of isolated metal sites, regulation of the coordination environment of isolated metal atoms, and fabrication of dimetallic single-atom sites for attaining optimal geometric and electronic structures of M-N-C materials and further correlate these structures with catalytic selectivity to various C1 (e.g., CO and CH₄) and C2 products in the CO₂RR. Moreover, constructive strategies to further optimize M-N-C materials for electrocatalytic CO₂RR are provided. Finally, the challenges and future research directions of the application of M-N-C materials for electrocatalytic CO₂RR are proposed.