Highly efficient CO2 electrochemical reduction on dual metal (Co–Ni)–nitrogen sites

Abstract

The electrochemical reduction (ECR) of CO₂ is a promising approach for CO₂ removal and utilization, which is a critical component of the circular carbon economy. However, developing efficient and selective electrocatalysts is still challenging. Single-atom catalysts (SACs) have gained attention because they offer high metal atom utilization and uniform active sites. However, tuning the active metal centres to achieve high activity and selectivity in CO₂ reduction remains a significant challenge. This study presents a novel electrocatalyst (Co–Ni–N–C) for CO₂ ECR on the diatomic metal–nitrogen sites prepared through ion exchange using a zeolitic imidazolate framework (ZIF) as a precursor. During pyrolysis, nitrogen-doped graphitic carbon serves as the host material, anchoring the diatomic Co–Ni sites. The resulting bimetallic active sites demonstrate exceptional performance, achieving a high CO yield rate of 53.36 mA mg_cat.⁻¹ and an impressive CO faradaic efficiency of 94.1% at an overpotential of −0.27 V. Spectroscopic, microscopic, and density functional theory (DFT) analyses collectively unveil the crucial synergistic role of the Co–Ni–N₆ moiety in promoting and sustaining exceptional electrocatalytic activities. The successful utilization of bimetallic sites in enhancing catalyst performance highlights the potential of this approach in developing efficient electrocatalysts for various other reactions.