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

The substitution of an oxygen evolution reaction with more thermodynamically favourable organic oxidation reactions (OORs) offers a promising strategy for energy-efficient hydrogen evolution and hydrogenation reactions. However, the kinetics of the cathodic reduction reaction is still hindered by sluggish OORs. Herein, we report a decoupled electrolysis strategy to realize a kinetically accelerated hydrogen evolution reaction (HER), a model reduction reaction, for the simultaneous production of H ₂ and valuable chemicals via the use of a solid redox mediator. The decoupled system with a rechargeable capability features a HER paired with redox mediator oxidation to store electricity and subsequently OORs to value-added chemicals coupled with the reduction of the oxidized redox mediator to generate electricity. Owing to the rapid kinetics of redox mediator oxidation and operation in a membrane-free cell, the kinetics of the HER are notably accelerated compared with those of conventional overall water splitting and OORs-paired HER systems. The value-added chemicals and electricity are cocreated during the discharging process, offering more economic benefits. Importantly, the design of such decoupled systems is universally applicable to OORs-paired electrocatalytic reduction systems (e.g., acetylene semihydrogenation) to synthesize various chemicals for electricity storage and generation, paving a sustainable avenue for energy-efficient H ₂ and chemical manufacturing.