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 Ti₃C₂T_x MXene (Cu SA@N-Ti₃C₂T_x) 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 Ti₃C₂T_x. The Cu SA@N-Ti₃C₂T_x 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.