Boosting CO2 Electroreduction to CH4 via Tuning Neighboring Single-Copper Sites

We report single-atom Cu catalysts dispersed on nitrogen-doped carbon by a nitrogen-coordination strategy. The presence of nitrogen enabled good dispersion and attachment of atomic Cu species on the nitrogen-doped carbon frameworks with Cu–Nx configurations. The Cu doping concentrations and Cu–Nx configurations were well-tuned by the pyrolysis temperature. At a high Cu concentration of 4.9%mol, the distance between neighboring Cu–Nx species was close enough to enable C–C coupling and produce C2H4. In contrast, at Cu concentrations lower than 2.4%mol, the distance between Cu–Nx species was large so that the electrocatalyst favored the formation of CH4 as C1 products. Density functional theory calculations further confirmed the capability of producing C2H4 by two CO intermediates binding on two adjacent Cu–N2 sites, while the isolated Cu–N4, the neighboring Cu–N4, and the isolated Cu–N2 sites led to formation of CH4. Our work demonstrates a facile approach of tuning active Cu sites for CO2 electroreduction to different hydrocarbons.