Electrocatalytic dual hydrogenation of organic substrates with a Faradaic efficiency approaching 200%

The wide deployment of electrocatalytic hydrogenation may be hindered by intrinsic limitations, including substrate solubility and difficult separation of the products from the electrolyte. The use of palladium membrane electrodes can overcome the aforementioned limitations by physically separating the formation of reactive hydrogen atoms from the hydrogenation of unsaturated organic substrates. Here, by taking advantage of the low-potential oxidation of formaldehyde on a palladium membrane anode to produce hydrogen that can permeate through the membrane electrode, we demonstrate that electrocatalytic dual hydrogenation of unsaturated dicarboxylic acids is possible when another palladium membrane electrode is also adopted as the cathode. Such a design enables the electrocatalytic hydrogenation of the same substrate at both the anode and cathode in two separated chambers spatially isolated from the electrochemical cell with a theoretical maximum Faradaic efficiency of 200%.