Redox-mediated electrocatalytic and photocatalytic hydrogen production

Electrocatalytic and photocatalytic water splitting for H-2 production, when driven by renewable energy sources, provide sustainable ways to reduce the use of fossil fuels and CO2 emissions for various applications. However, both encounter various challenges induced by gas mixing due to the simultaneous generation of H-2 and O-2 in the same cell compartment. The redox-mediated H-2 generation process, which employs soluble redox species to serve both as charge carrier through electrolyte solution and electron donor (or acceptor) at the surface of catalyst for decoupled hydrogen evolution reaction, has shown an intriguing potential to mitigate the above issues. This short review briefly introduces the design principle and reaction mechanism of some representative redox-mediated electrocatalytic and photocatalytic water splitting systems in which the recent advancements are highlighted and their potential are evaluated for practical applications.