Surface electron-donor-boosting single-atom nickel sites for CO2 electroreduction in pure water

Abstract

The electrocatalytic carbon dioxide reduction reaction (CO₂RR) in pure water is one of the most promising strategies for avoiding crystallization in conventional electrolytes. Here, we sought to modify the catalyst of dispersed single-atom nickel (Ni) sites on an ultrathin nitrogen-doped carbon nanosheet (Ni–N–C) by using amino groups (Ni–N–C–NH₂). The obtained Ni–N–C–NH₂ catalysts exhibited a peak turnover frequency of 11.1 s⁻¹ with >90% CO selectivity and ultrastable durability of 100 h of continuous operation and achieved two to three times greater current density than Ni–N–C. Operando spectroscopic evidence combined with theory studies suggested that the improved CO selectivity originates from the synergistic effect of the amino groups and Ni–N–C. The introduced amino groups with the surface property of the electron donor upshift the d-band center of Ni and favor CO₂ capture and proton-coupled electron transfer, ultimately enabling highly efficient operation of the CO₂RR on Ni–N–C catalysts.