Surface Lattice Oxygen Confined Hydrogen Transfer for Electrochemical Acetonitrile Hydrogenation

Abstract

Electrochemical synthesis of ethylamine from acetonitrile with H₂O is a promising alternative to the traditional H₂-based process but is challenged by the sluggish hydrogenation process with the inefficient supply of active hydrogen species (H*). Herein, we report an accelerated hydrogen transfer strategy to facilitate on-site electrochemical hydrogenation of acetonitrile for ethylamine synthesis. This strategy was realized by a monolithic electrode composed of oxygen vacancies (OVs)-rich titanium dioxide nanoarrays grown on Ti foam in combination with Ni single atoms (Ni₁/OVs-TiO₂ NA), which enabled the efficient electrochemical water dissociation into H* along with the optimized electronic structure of surface lattice oxygens by leveraging adjacent OVs, effectively weakening the binding strength of O–H bonds for the subsequent fast transfer of confined H* mediated by surface lattice oxygens. With further incorporation of Ni single atoms as H* trapping centers for the hydrogenation step, the as-prepared Ni₁/OVs-TiO₂ NA delivered an impressive electrocatalytic performance of acetonitrile hydrogenation with an ethylamine yield rate of 6.93 mmol h^–1 mg_Ni^–1 and a Faraday efficiency of 94%, 8.8-fold higher than that of OVs-free counterpart (0.78 mmol h^–1 mg_Ni^–1, 39%). This work clarifies the promotion effect of surface lattice oxygen on hydrogen-transfer-related electrochemical hydrogenation reactions and offers a water-based ethylamine synthesis strategy.