Noble-Metal-Free Ni-W-O-Derived Catalysts for High-Capacity Hydrogen Production from Hydrazine Monohydrate

Development of active and earth-abundant catalysts is pivotal to render hydrazine monohydrate (N₂H₄·H₂O) viable as a hydrogen carrier. Herein, we report the synthesis of noble-metal-free Ni-W-O-derived catalysts using a hydrothermal method in combination with reductive annealing treatment. Interestingly, the thus-prepared Ni-based catalysts exhibit remarkably distinct catalytic properties toward N₂H₄·H₂O decomposition depending upon the annealing temperature. From a systematic phase/microstructure/chemical state characterization and the first-principles calculations, we found that the variation of the apparent catalytic properties of these Ni-based catalysts should stem from the formation of different Ni-W alloys with distinct intrinsic activity, selectivity, and distribution state. The thereby chosen Ni-W alloy nanocomposite catalyst prepared under an optimized condition showed high activity, nearly 100% selectivity, and excellent stability toward N₂H₄·H₂O decomposition for hydrogen production. Furthermore, this noble-metal-free catalyst enables rapid hydrogen production from commercially available N₂H₄·H₂O solution with an intriguingly high hydrogen capacity of 6.28 wt % and a satisfactory dynamic response property. These results are inspiring and momentous for promoting the use of the N₂H₄·H₂O-based H₂ source systems.