Progress and perspectives on electrocatalytic transmembrane hydrogenation

Abstract

H₂-free electrochemical hydrogenation of unsaturated organic compounds has garnered considerable attention as a low-carbon and efficient alternative to conventional thermocatalytic hydrogenation. However, in a traditional electrolytic cell, the compounds need to dissolve in the electrolyte before participating in the catalytic reactions, resulting in difficulties in enhancing the compounds' yield, as well as product separation and purification. A Pd membrane reactor offers a solution to these challenges by enabling the separation of a hydrogenation reaction into electrochemical and chemical processes. Here we summarize the processes of the Pd membrane reactor which drive the electrochemical hydrogenation of unsaturated compounds including gaseous reagents. We discuss various modification strategies for Pd catalysts, including the fabrication of Pd nanodendrites, incorporation of foreign metal layers, and formation of Pd alloys with other metals. These strategies aim to enhance catalytic activity by increasing the active area and fine-tuning reactant adsorption. We place significant emphasis on using this membrane reactor to hydrogenate unsaturated bonds, including CC, CC, CN, CO, and OO bonds and highlight distinct catalysts to enhance catalytic selectivity. Finally, we provide some perspectives on the challenges and outlook for other electrochemical hydrogenation reactions through the Pd membrane reactor.