Pyrazole-Mediated\nOn-Surface Synthesis of Nickel/Nickel\nOxide Hybrids for Efficient Urea-Assisted Hydrogen Production

Creating densely functionalized supported materials without\naggregation\nhas been one of the ultimate goals for heterogeneous catalysts. Direct\nconversion of readily available bulk materials into highly dispersed\nsupported materials could be highly beneficial for real applications.\nIn this work, we invented an on-surface synthetic strategy for generating\nhighly loaded and well-dispersed nickel nanoparticles on nickel oxide\nsupports (Ni/NiO). This on-surface synthesis is a two-step process\ninvolving the surface transformation of Ni(OH)<sub>2</sub> into a\nlayer of chain-like nickel pyrazolate [Ni(pz)<sub>2</sub>] and an\nultra-high-vacuum annealing process that evacuates the pyrazole and\ndecomposes the Ni(OH)<sub>2</sub> into the Ni/NiO hybrid. The highly\ndispersed Ni/NiO catalyst exhibited superior activities and long-term\nstability for both the urea oxidation reaction and the hydrogen evolution\nreaction, which enables efficient urea electrolysis with a single\ncatalyst. This approach presents a novel on-surface synthetic strategy\nfor metal oxide-supported materials and offers efficient catalysts\nfor advanced urea-assisted hydrogen production.