Tailoring N-Coordination Species in Cu Single-Atom Catalysts for Selective Electrocatalytic CO ₂ -to-CH ₄ Conversion

Electrochemical carbon dioxide reduction (ECR) shows great potential in creating high-value carbon-based chemicals, while the design of advanced catalysts at the atomic level remains challenging. The electrocatalytic performance in ECR depends on the electronic structure of the catalysts, which can be effectively regulated by adjusting the local coordination environment. Herein, we prepared three kinds of porous single-atom CuNxN′yO catalysts with different ratios of pyridinic-N (N) and pyrrolic-N (N′) coordination by a template-pyrolysis-etching method at different temperatures. The CuNxN′yO catalyst obtained at 700 °C (CuN2N′2O) exhibited a 64.2 ± 2.3% methane (CH4) Faradaic efficiency and partial current density (jCH4) of 256.9 mA cm–2 in a flow cell, and the maximum jCH4 can reach 298.0 mA cm–2. Experimental characterization and density functional theory calculations indicate that the performance enhancement in ECR to CH4 is attributed to the comparable contents of N and N′ in CuN2N′2O, which leads to a moderate adsorption strength of *COOH and the smallest maximum free energy barrier (ΔGmax) among all prepared samples. This study paves the way for designing high-efficiency electrocatalysts with N-coordination species and offers additional insights into the underlying electrochemical reaction mechanisms.