Asymmetrically coordinated single atom Cu catalyst with unsaturated C-Cu-N structure for CO2 reduction to CO

Single atom catalysts (SACs) play a crucial role in energy catalysis due to their distinct coordination environment and high atomic utilization efficiency. This study focuses on the synthesis of a monatomic Cu catalyst with Cu–N1C1 coordination anchored to N-doped Ti3C2Tx MXene (Cu SA@N-Ti3C2Tx) to achieve efficient reduction of CO2 to CO. Detailed characterization, including morphology and multispectral analysis, confirmed the uniform distribution of asymmetrically coordinated Cu atoms in unsaturated C–Cu–N bridge fragments on Ti3C2Tx. The Cu SA@N-Ti3C2Tx catalyst exhibited an excellent CO selectivity with Faraday efficiency of 97.4% at −0.58 V vs. reversible hydrogen electrode (RHE) and satisfactory durability. The in situ X-ray absorption fine structure (XAFS) results confirmed that the carbon dioxide reduction reaction (CO2RR) product distribution is mainly affected by potential-dependent valence change of Cu species. These findings highlight the extensive potential of tuning coordination structure of MXene-based single-atom catalysts for CO2 reduction reactions.