Bimetallic Ni/Co single-atom catalysts guided by an energy descriptor for efficient CO2 electroreduction to syngas†

Electrochemical CO₂ reduction to syngas (CO + H₂) offers a promising way to produce valuable chemicals and fuels from renewable electricity and capture CO₂, but developing efficient, tunable catalysts to control the syngas ratio remains challenging. Herein, we demonstrated the rational design of bimetallic Ni/Co single-atom catalysts for efficient, tunable CO₂ electroreduction to syngas. The adsorption energy descriptor was introduced to identify optimal metal–N₄ sites for CO₂ electroreduction, highlighting Ni–N₄ and Co–N₄ as promising candidates. Isolated Ni and Co atoms were precisely anchored into nitrogen-doped carbon supports, forming Ni/Co–N₄ active sites. Mechanistic insights revealed that atomic Ni–N₄ sites selectively adsorbed and activated CO₂ to form CO, while Co–N₄ sites bound H₂O to facilitate hydrogen evolution. This synergy between Co/Ni single-atom sites enabled high faradaic efficiency and a tunable CO/H₂ ratio from 1 : 2.3 to 2.8 : 1. This research offers strategies for designing single-atom catalysts to achieve precise product selectivity control over energy-related applications.