Charge redistribution of Mo-incorporated Fe2Ni2N customizes potential-determining step for highly selective electroreduction of nitrobenzene to azoxybenzene

Selective electroreduction of nitrobenzene (NB) to generate valuable azoxybenzene (AOB) is an important electrochemical N-N coupling reaction, but suffering from low selectivity at low potential. Herein, we constructed a Mo-incorporated NiFe bimetallic nitride on nickel foam (Mo-Fe 2 Ni 2 N/NF), effectively catalyzing selective electroreduction of NB (NSR) to generate AOB. Experimental and theoretical findings reveal that incorporating Mo into Fe 2 Ni 2 N triggers a rational charge redistribution, which induces a moderate hydrogen affinity, alongside enhances the adsorption of nitrosobenzene and phenylhydroxylamine intermediates so as to lower energy barrier of potential-determining step (PDS) for formation of AOB and higher energy barriers of PDS for formation of by-products (amine and azobenzene) can be achieved, thus leading to desired tandem reactions of partial hydrogenation reduction and bimolecular coupling for selective electrosynthesis of AOB. As a result, Mo-Fe 2 Ni 2 N/NF exerts an ultralow potential (0.341 V@100 mA cm −2 ) along with 100 % conversion of NB and 97.2 % yield of AOB. Remarkably, an anion exchange membrane flow electrolyzer of pairing cathodic NSR with anodic benzylamine oxidation by using Mo-Fe 2 Ni 2 N/NF cathode and Mo x Ni y N/NF anode is integrated, and simultaneous synthesis of value-added, easy-separation AOB and benzonitrile can be accomplished with low voltage (1.50 V@100 mA cm −2 ) and high productivity (> 90 %), highlighting its large potential for industrial application. This work showcases a new route to design efficient electrocatalysts for organic electrosynthesis via manipulating adsorption of key reaction species of constructing multicomponent nitrides.