Coordination-assisted pyrolysis of Ni complexes for highly dispersed catalysts with enhanced CO2 electroreduction selectivity

Abstract

In this work, a coordination-assisted pyrolysis strategy using 4,4′-bipyridine as the molecular ligand was developed to coordinate Ni²⁺ ions, successfully loading highly dispersed and uniform nanoscale nickel particles (Ni-NC) on nitrogen-doped carbon nanotubes. Compared with the traditional large-sized nickel nanoparticle catalyst (Ni@N), Ni-NC exhibited significantly enhanced activity and selectivity in the electrochemical carbon dioxide reduction reaction. Ni-NC achieves a high Faradaic efficiency for CO (FE_CO) of 95.6 % at −0.87 V vs. RHE and maintains excellent electrochemical stability for over 8 h in an H-cell. In a flow cell, Ni-NC delivers a current density of −207 mA cm⁻² at −0.9 V, and reaches 99 % FE_CO at −0.5 V vs. RHE. Notably, FE_CO remains above 90 % across a wide potential window (−0.4 to −0.8 V vs. RHE) and a high FE_CO above 90 % during continuous 25 h operation at −0.5 V vs. RHE. This work demonstrates an effective ligand-directed strategy for preparing highly dispersed metal-based catalysts with enhanced CO₂ electroreduction performance.