Mechanistic Insights into the Electrocatalytic Hydrogenation of Alkynes on Pt–Pd Electrocatalysts in a Proton-Exchange Membrane Reactor

Abstract

The electrocatalytic semihydrogenation of alkynes to (Z)-alkenes using a proton-exchange membrane (PEM) reactor has been studied as an alternative to the Lindlar catalytic system. We recently reported that Pt–Pd electrocatalysts achieved both a high (Z)-alkene selectivity and a high (Z)-alkene production rate. However, the mechanism of hydrogenation on Pt–Pd electrocatalysts has been not elucidated. In the present study, we systematically investigated the electrocatalytic hydrogenation of alkynes in a PEM reactor using Pt–Pd electrocatalysts with various compositions and identified the active sites on the Pt–Pd electrocatalysts via detailed characterizations. In addition, the roles of both the Pt and Pd metals of the Pt–Pd electrocatalysts in the electrocatalytic hydrogenation of alkynes were clarified via voltammetric studies, and a synergistic mechanism of electrocatalytic hydrogenation was proposed.