Modulation of d-band electron enables efficient CO2 electroreduction towards CO on Ni nanoparticles

Abstract

Ni nanocatalysts have been widely utilized in various electrocatalytic reactions, but they are rarely reported in CO₂ reduction reaction (CO₂RR), duo to their pronounced affinity for *CO adsorption and high activity in competitive hydrogen evolution reaction (HER). In this research, highly graphitized N-doped carbon nanofibers with porous structure (PCNF) are introduced as the conductive and stable substrate for the uniformly distributed Ni nanoparticles (Ni–PCNF). Theoretical calculations demonstrate that this superior carbon substrate can modulate the local electron density within the 3d orbitals of Ni sites, and directly affect their adsorption and desorption energies of *CO intermediates. After the introduction of PCNF, the dominant HER activity is successfully transformed into CO₂RR activity. Consequently, Ni–PCNF catalyst demonstrates exceptional CO₂RR performance, and obtains remarkable CO Faraday efficiencies (FE_CO) exceeding 90% with current densities up to 241 mA cm⁻². Furthermore, the porous carbon substrate can facilitate the exposure of Ni nanoparticles, and bring forth an impressive mass activity of 3.44 A mg_Ni⁻¹. This work provides valuable insights into the rational design of advanced Ni-based catalysts for CO₂ reduction and various electrocatalytic reactions.