Combined anodic and cathodic hydrogen production from aldehyde oxidation and hydrogen evolution reaction

Hydrogen production through water electrolysis is of considerable interest for converting the intermittent electricity generated by renewable energy sources into storable chemical energy, but the typical water electrolysis process requires a high working voltage (>1.23 V) and produces oxygen at the anode in addition to hydrogen at the cathode. Here we report a hydrogen production system that combines anodic and cathodic H2 production from low-potential aldehyde oxidation and the hydrogen evolution reaction, respectively, at a low voltage of ~0.1 V. Unlike conventional aldehyde electrooxidation, in which the hydrogen atom of the aldehyde group is oxidized into H2O at high potentials, the low-potential aldehyde oxidation enables the hydrogen atom to recombine into H2 gas. The assembled electrolyser requires an electricity input of only ~0.35 kWh per m3 of H2, in contrast to the ~5 kWh per m3 of H2 required for conventional water electrolysis. This study provides a promising avenue for the safe, efficient and scalable production of high-purity hydrogen.