Tuning N coordination environment in Ag[sbnd]N[sbnd]C single atom catalysts for efficient electrochemical CO2-to-Ethanol conversion.

In this work, single-atom Ag anchored on nitrogen-doped carbon catalysts are designed to investigate the effect of different N -coordination environments on the ECO 2 RR products pathway. The combination of experiments and theory calculations reveal that the Ag-N 4 -C (pyrrolic N) site facilitates the adsorption of CO 2 to produce CO, whereas Ag-N 3 -C (pyridine N) exhibits the highest binding energy (-4.73 eV) to hold *CO intermediates for dimerization, consequently steering the pathway to ethanol (C 2 H 5 OH) formation with a FE of 42% at −0.97 V vs. RHE. [Display omitted] • Ag N C catalysts with controllable N species and content were prepared. • ECO 2 RR products from CO to C 2 H 5 OH can be regulated. • Ag-N-rGO 0.025 M with pyrrolic N promotes the production of CO. • Ag-N-C 0.05 M with pyridine N facilitates a FE C2H5OH of 42 % at −0.97 V RHE. • Experiments and DFT calculations reveal the structure–activity relationship. The rational modulation of the coordination environment of the active center of single-atom catalysts (SACs) is a potential strategy to improve the activity and selectivity of electrocatalytic CO 2 reduction. We developed a series of single-atom Ag-anchored on N -doped carbon catalysts with different N -coordination environments by regulating the carbon source (glucose/graphene oxide, GO). Results demonstrated that the CO 2 -to-CO/C 2 H 5 OH pathway can be converted through reasonable regulation of the content of pyrrolic N and pyridine N. At a highly dominant pyrrolic N content of 40.0 %, the electrocatalyst of Ag-N-rGO 0.025 M facilitates the formation of CO with a Faradaic efficiency (FE) of 69.7 %. By contrast, when the pyridine N content is 70.5 %, the best Ag-N-C 0.05 M catalyst in the H-cell shows an FE of 42 % for C 2 H 5 OH at −0.97 V vs. RHE; moreover, the FE is stable at 40 % within 31 h. Density functional theory calculations further confirm that the pyrrolic N site is conducive to the conversion of CO 2 to intermediate *CO, whereas pyridine N exhibits the highest binding energy (ΔG = -4.73 eV) to hold *CO intermediates for dimerization, consequently steering the pathway to the formation of C 2 H 5 OH. The results of this study provide novel insights into the rational design of carbon-based SACs based on efficient electrochemical CO 2 reduction reaction and the regulation of CO 2 selectivity and activity for C 2 H 5 OH production. [ABSTRACT FROM AUTHOR]