The electrochemical CO₂ reduction reaction (CO₂RR) to multi-carbon (C₂₊) products relies predominantly on Cu-based catalysts, but achieving high selectivity and efficiency remains challenging. The formation of C₂₊ products generally involves *CO generation and subsequent dimerization, making the modulation of *CO adsorption behavior critical. Herein, we developed N doped carbon nanosheets supported monatomic Ni and ultrafine oxide-derived Cu in amorphous state as a tandem catalyst. The Ni-N₄ sites enable a high *CO coverage, while the amorphization of the oxide-derived Cu nanoparticles induces a shift in the *CO adsorption configuration from atop to bridging, thereby facilitating the C–C coupling. These integrated effects endow the catalyst with exceptional performance, achieving a record Faradaic efficiency of ~ 70% for C₂₊ products and ~ 54% for C₂H₄. This work provides a strategy for designing tandem catalyst for CO₂RR multiscale component interaction.

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.