Recent advances in anodic hydrogen production: Electrochemical oxidative dehydrogenation of aldehydes to carboxylates

Electrooxidation of aldehydes to carboxylates has been observed to yield H₂ at small anodic potentials on Group IB metal electrodes (mainly Cu, Ag, and Au) in alkaline media. When paired with hydrogen evolution at the cathode, only one mole of electrons is transferred to generate a mole each of hydrogen and carboxylate product. Recently, this phenomenon of electrochemical oxidative dehydrogenation (EOD) has gained renewed interest as it has been demonstrated with biomass-derived substrates at industrially relevant current densities. The high electron efficiency, low cell voltage, and valuable anode products of EOD all give cause for further investigation into its prospects for co-producing renewable hydrogen and organic chemicals. Currently, the underlying mechanism of EOD remains unclear. This contribution reviews the present understanding of the reaction mechanism and highlights notable performance benchmarks to date, emphasizing the role of catalyst material and reaction conditions.