Electric power can be generated from renewable energy sources such as solar and wind, making electrocatalytic hydrogenation an important technology to reduce carbon dioxide emissions in the organic synthesis industry. In the present work, the electrocatalytic semihydrogenation of diphenylacetylene was carried out in a proton exchange membrane (PEM) reactor with carbon-supported Pt, Pd, and Pt–Pd alloy cathode catalysts. Diphenylacetylene introduced into the PEM reactor at less negative potentials underwent electrocatalytic hydrogenation to provide cis-stilbene as a main stereoisomer, with excellent current efficiencies. Among the investigated catalysts, the Pt–Pd alloy with a composition of 1(Pt):99(Pd) was found to be the most suitable for achieving both high cis-stilbene selectivity and a high production rate (partial current density) for cis-stilbene.

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.

No abstract

No abstract

No abstract