Theoretical understanding of the electro-reduction of acetonitrile into ethylamine on copper: a hydride-proton stepwise mechanism

Abstract

The electrochemical acetonitrile reduction reaction (ANRR) provides a promising strategy for ethylamine production and hydrogen storage. Copper-based electrodes have shown distinctive capability in the electrochemical ANRR. Despite extensive exploration of the ANRR, the detailed mechanism remains poorly elucidated. Here, we present a comprehensive kinetic study of the ANRR towards ethylamine, including the potential-dependent competition with the hydrogen evolution reaction (HER) by using the charge extrapolation method. The activation of acetonitrile limits the activity, and the significant charge transfer in proton reduction compared to acetonitrile activation leads to decreased ANRR selectivity at high overpotential. The concerted effort of surface hydride and protons is emphasized in the hydrogenation of the polar cyano group. We suggested that promoting water dissociation to supply *H and enhancing surface *H migration to expedite acetonitrile activation could be an efficient strategy in developing highly active and selective electrocatalysts for the ANRR.