Modulating the Coordination Structure of Dual-Atom Nickel Sites for Enlarging CO2 Electroreduction Potential Window

Abstract

CO₂ electroreduction (CO₂ER) is a promising way to change CO₂ into useful CO. However, high CO selectivity can only be realized in a narrow potential range, which largely limits its practical availability. Herein, the potential range for efficient CO₂-to-CO conversion is effectively enlarged by developing dual-atom Ni sites with surrounding uncoordinated N dopants dispersed in carbon nanotube substrate. This catalyst is synthesized through a novel precursor gas diffusion strategy to manipulate the coordination structures of atomic Ni. Remarkably, the dual-atom catalyst exhibits a CO Faradaic efficiency above 92% in an ultra-wide potential window from a low onset potential of −0.25 to −1.4 V (vs RHE), much superior to those state-of-the-art atomic catalysts. Mechanistically, the unique dual-atom Ni sites with uncoordinated graphitic N dopants can thermodynamically promote CO₂-to-CO process via stabilizing the key ^*COOH intermediate, while simultaneously suppressing the parasitic hydrogen evolution. The findings reveal the correlation between the tailored coordination structures and CO₂ER performance, so as to further guide the design of atomically dispersed catalysts for CO₂ER process.