Nickel Single Atom Density‐Dependent CO2 Efficient Electroreduction

Abstract

AbstractThe transition metal–nitrogen–carbon (M─N─C) with MNx sites has shown great potential in CO2 electroreduction (CO2RR) for producing high value‐added C1 products. However, a comprehensive and profound understanding of the intrinsic relationship between the density of metal single atoms and the CO2RR performance is still lacking. Herein, a series of Ni single‐atom catalysts is deliberately designed and prepared, anchored on layered N‐doped graphene‐like carbon (x Ni1@NG‐900, where x represents the Ni loading, 900 refers to the temperature). By modulating the precursor, the density of Ni single atoms (DNi) can be finely tuned from 0.01 to 1.19 atoms nm−2. The CO2RR results demonstrate that the CO faradaic efficiency (FECO) predominantly increases from 13.4% to 96.2% as the DNi increased from 0 to 0.068 atoms nm−2. Then the FECO showed a slow increase from 96.2% to 98.2% at −0.82 V versus reversible hydrogen electrode (RHE) when DNi increased from 0.068 to 1.19 atoms nm−2. The theoretical calculations are in good agreement with experimental results, indicating a trade‐off relationship between DNi and CO2RR performance. These findings reveal the crucial role of the density of Ni single atoms in determining the CO2RR performance of M─N─C catalysts.