The low-cost hydrogen production from water electrolysis is crucial for deployment of sustainable hydrogen economy, but is currently constrained by the lack of active and robust electrocatalysts from Earth-abundant materials. We describe here an unconventional heterostructure composed of strongly coupled Ni-deficient LixNiO nanoclusters and polycrystalline Ni nanocrystals, and its exceptional activities toward hydrogen evolution reaction (HER) in aqueous electrolytes. The presence of lattice oxygen species with strong Brønsted basicity is a significant feature in such heterostructure, which spontaneously split water molecules for accelerated Volmer H-OH dissociation in neutral and alkaline HER. In combination with the intimate LixNiO and Ni interfacial junctions that generate localized hotspots for promoted hydride coupling and hydrogen desorption, the catalysts produce hydrogen at the current density of 10 mA cm -2 under overpotentials of only 20, 50 and 36 mV in acidic, neutral and alkaline electrolytes, respectively, making them among the most active Pt-free catalyst developed thus far. In addition, such heterostructure also exhibited superior activity towards the hydrogen oxidation reaction in alkaline electrolyte.

on materials synthesis using novel precursors or structural templates that target Ni 2 Mo 6 S 8 nanoclusters may significantly accelerate the development of such catalysts. The results presented here provide new design principles for rational active sites motifs with earth-abundant elements for sustainable and decentralized H 2 O 2 production.

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