Dual active sites engineering of electrocatalysts for alkaline hydrogen evolution

Hydrogen evolution reaction (HER) in alkaline medium plays an important role in producing green hydrogen but suffers from sluggish reaction kinetics owing to additional water dissociation step. Extensive research interest has been placed on engineering dual active sites (i.e., water-dissociation sites and hydrogen-adsorption/recombination sites) within a catalyst to enhance the HER activity. This article reviews recent progress in developing alkaline HER catalysts with high-efficiency dual active sites via strategies of heterogeneous interfaces constructing and heteroatoms doping or alloying. The latest advances in the component design, synthetic strategy, catalytic performance, and mechanistic understanding are discussed with selective examples of the hybrid between metal/alloy or metal phosphide/nitride/sulfide and transition metal hydroxides, oxyhydroxide or bicarbonates. Furthermore, remaining challenges and perspectives in the field of dualsite engineering are highlighted for future development of better alkaline HER electrocatalysts.