Cascading of Thermocatalysis and Electrocatalysis for Enhanced Nitrogen Reduction on the Dual-Atom Cobalt Catalyst

Electrochemical ammonia (NH₃) synthesis is an attractive approach for nitrogen fixation due to its advantages in operating under mild conditions and using compact production facilities. However, it faces technoeconomic challenges, such as slow N₂ conversions. In recent years, N≡N bond activation has been reported by either enhancing the "acceptance-donation" mechanism on a single atomic site or stretching the bond length of N₂ on dual atomic sites. In either approach, nevertheless, the concerted proton-electron transfer (CPET) that activates *N₂ directly to *NNH exhibits sluggish reaction kinetics. Here, we demonstrate that *N₂ can be feasibly hydrogenated via a thermally and electrically cascaded mechanism on a dual Co atom catalyst (Co₂-C₃N₄). To be specific, when the N₂ bonds with one of the Co atoms in Co₂-C₃N₄, the CPET occurs at adjacent C atoms rather than *N₂, resulting in a *H(C)-*N₂(Co) intermediate state. The vital state *NNH can then be formed via thermally activated stepwise H migrations from C to *N₂. Correspondingly, the electrochemical reduction of N₂ to ammonia can proceed at low work potentials.