From catalyst functional zoning to air oxidation–nitrogen oxide reduction cascade: An effective pathway for ammonia synthesis from air

Electrocatalytic nitrogen oxide reduction to ammonia, centered on nitrate reduction, faces challenges including insufficient catalyst activity and stability, along with difficulties in integrated application. Using Salen (N-N′-bis (salicylidene)-1,3-propanediamine) as ligand, this work uniformly introduces multi-dimensional iron species onto carbon fibers surface (named FeSCN/CF) via complexation confinement and hard template confinement. Fe SCN /CF efficiently promotes nearly 100% electroreduction of nitrate-to-ammonia under various complex conditions, and the Zn-nitrate battery constructed with FeSCN/CF as the core enables self-driven ammonia synthesis alongside stable energy supply. Driven by intermittent electrical energy, a low-temperature plasma air oxidation process cascaded with an electrocatalytic unit enables direct air-to-ammonia conversion, successfully demonstrated in a distributed agricultural ammonia fertilizer supply scenario. Experimental and theoretical calculations confirm that multiscale/multitype sites synergistically promote highly selective electroreduction of nitrogen oxides to ammonia, while a self-driven plasma-air-oxidation cascade electroreduction system powered by green electricity effectively addresses nitrogen source shortages and adapts to distributed ammonia synthesis.