Decoupled electrolysis for water splitting

Decoupled electrolysis provides a means by which to run the oxygen evolution and hydrogen evolution reactions of water splitting in different places, at different times and/or at rates that are not linked to each other. As a result, the gaseous products of water splitting can be kept separate, and the rate of the (more valuable) hydrogen evolution process can be freed from its dependence on the rate of the (generally more sluggish) oxygen evolution reaction. Decoupled water electrolysis, therefore, has significant potential benefits for the sustainable production of hydrogen from water driven by intermittent renewable power sources. In this Current Opinion article, we give an overview of recent progress in the field of decoupled electrolytic water splitting (with a particular emphasis on the years 2018–2020) and discuss some of the future prospects of this rapidly-developing area.