Decoupling charge‒discharge electrolysis for hydrogen evolution and organic oxidation reactions

Replacing the oxygen evolution reaction with more thermodynamically favourable organic oxidation reactions (OORs) can enable energy-efficient hydrogen evolution and hydrogenation. However, cathodic reduction rates are limited by sluggish OORs. Herein, we report a decoupled electrolysis strategy using a solid redox reservoir (RR) to realize an optimized hydrogen evolution reaction (HER) paired with valuable chemical synthesis. The decoupled system with a rechargeable capability features a HER coupled with RR oxidation for electricity storage, which is followed by the conversion of OORs (e.g., ethylene glycol, glycerol) into value-added chemicals coupled with the reduction of the oxidized RR to generate electricity. The fast kinetics of RR oxidation and membrane-free cell operation optimize the HER rate. The value-added chemicals and electricity are cocreated during the discharge process, offering more economic benefits. This decoupling design is universally applicable to other OORs-paired reduction systems (e.g., acetylene-to-ethylene semihydrogenation) to synthesize various chemicals for electricity storage and generation, paving a sustainable avenue for H2 production/hydrogenation and chemicals manufacturing. Using thermodynamically favourable organic oxidations instead of oxygen evolution enables energy-efficient cathodic reactions, but rates are limited by slow anodic kinetics. Here, the authors report decoupled charge‒discharge electrolysis using a solid redox reservoir to overcome this limitation.