Cu-Terminated Ti3CuC2: Boosting CO2 Reduction Via Selective Adsorption Regulation

The electrochemical CO2 reduction reaction (CO2RR) on Cu surfaces is constrained by the scaling relations among intermediate adsorption energies. We demonstrate that Cu-terminated Ti3CuC2, featuring an atomically thin Cu monolayer, is an efficient CO2RR catalyst. Charge transfer from Ti3C2 to Cu enriches the reaction sites with electrons and thus reconstructs their local electronic environment, downshifting the Cu d-band center. This regulation selectively enhances CO2 adsorption while it attenuates CO binding. The potential-determining step is hence diverted from *CO + H+ + e- → *CHO to alternative steps (ΔG = 0.02 eV). Such a mechanistic shift leads to low limiting potentials of -0.20 V for CH3OH and -0.30 V for CH4, simultaneously transforming the formidable C-C coupling into an exothermic process (ΔG = -0.10 eV) and enabling favorable pathways toward C2H4 and C2H5OH. These findings establish the selective regulation of CO2/CO adsorption as a promising design principle for efficient CO2RR catalysts.