Targeted Regulation of the Electronic States of Nickel Toward the Efficient Electrosynthesis of Benzonitrile and Hydrogen Production.

Abstract

Highly efficient electro-oxidation of benzylamine to generate value-added chemicals coupled with the hydrogen evolution reaction (HER) is crucial but challenging. Herein, targeted regulation of the electronic states of Ni sites was realized via simple yet precise nitridation engineering. Benefiting from the insertion of N atoms into the Ni lattice, the Ni3N electrode exhibits superior activity, selectivity, and stability for the benzylamine oxidation reaction (BOR). Especially, under the industrially relevant current (∼250 mA), the Ni3N catalyst remains ∼95% selective for benzonitrile production, reaching 1.43 mmol h-1 cm-2. Experimental and theoretical findings reveal that the formation of Ni-N bonds upshifts the Ni d-band center and optimizes the electrophilic properties of Ni sites, which contributes to the adsorption and dehydrogenations process of benzylamine. Furthermore, due to the work function difference between Ni and Ni3N, a strong mutual interaction occurs at the heterogeneous interface for Ni-Ni3N, which endows it with the appropriate H* adsorption energy and thus excellent HER performance. Impressively, the integrated solar-energy-driven BOR coupled with the HER electrolyzer affords 10 mA cm-2 at an ultralow voltage of 1.4 V and exhibits a promising practical application (ηsolar-to-hydrogen = 13.8%). This work offers a new perspective for the bifunctional design of nitrides in the field of electrosynthesis.