Synergistic Cu@Ni-N-C Yolk@Shell Nanostructure Catalyst for Selective Acetonitrile Electroreduction to Ethylamine.

Electrochemical upgrading, such as acetonitrile (CHCN) reduction to ethylamine (CHCHNH, EtNH), represents a promising route for the mild synthesis of value-added chemicals with renewable energy sources. However, a lack of an in-depth understanding of the hydrogenation mechanism hinders the rational development of efficient electrocatalysts to boost EtNH electrosynthesis. Here, an innovative confinement strategy is reported to an efficient yolk@shell-structured Cu@Ni-N-C catalyst, comprising inner Cu nanorods and outer atomically-dispersed Ni on a nitrogen-doped carbon layer, for high-performance electrochemical CHCN reduction toward CHCHNH generation. The introduction of Ni-N-C tailors the electronic structure of Cu, and more importantly, turns its reaction pathway from a direct electroreduction (DER) mechanism into a more favorable electrochemical hydrogenation (ECH) mechanism, where H intermediate is first generated at outer Ni-N-C layer through the proton-coupled electron transfer process and then interacts with the adsorbed CHCN molecules at inner Cu nanorods. As a consequence, the kinetic energy barrier of electrochemical CHCN reduction is significantly reduced, thereby leading to a boosted activity, selectivity, and stability of Cu@Ni-N-C electrocatalyst with respect to bare Cu counterpart. This work provides insights into the rational design of synergistic yolk@shell catalysts for multi-step electrochemical upgrading reactions with an optimized hydrogenation mechanism.