Bimetallic nanoparticles encapsulated within a graphitized nitrogen-doped carbon shell for efficient pH-universal electrochemical carbon dioxide reduction.

The large-scale production of carbon monoxide (CO) through electrochemical carbon dioxide (CO) reduction reaction (eCORR) is a promising strategy for mitigating CO emissions and energy crisis. However, developing high-efficiency, cost-effective, stable, and pH-universal electrocatalysts for eCORR is of utmost urgency. In this study, nickel-zinc bimetallic nanoparticles encapsulated within a graphitized nitrogen-doped carbon shell (NiZn-NiZnC@NC) were synthesized and used as robust electrocatalysts for the eCORR-to-CO process. The catalysts were constructed via facile annealing of a zeolitic imidazolate framework precursor with boric acid (HBO) as a precursor to improve the mesoporous structures for enhanced electrolyte accessibility and CO diffusion. Furthermore, the addition of HBO before the pyrolysis process allowed carbon atoms to dissolve and diffuse in the NiZn structure, forming the NiZn-NiZnC composite, which afforded rich exposed active sites for eCORR. Benefiting from the unique structure, the NiZn-NiZnC@NC electrocatalyst exhibited high Faradaic efficiency of CO (close to 95 %) and long-term durability in alkaline, neutral, and acidic media during the entire experimental duration. Particularly, the partial current densities of CO reached approximately 375 mA cm in all electrolytes. Density functional theory calculations revealed that NiZn-NiZnC@NC exhibited an optimized binding energy for the key intermediate *COOH, efficiently suppressing the hydrogen evolution reaction while enhancing the eCORR-to-CO performance.