Pyrazole-Mediated On-Surface Synthesis of Nickel/Nickel Oxide Hybrids for Efficient Urea-Assisted Hydrogen Production.

Creating densely functionalized supported materials without aggregation has been one of the ultimate goals for heterogeneous catalysts. Direct conversion of readily available bulk materials into highly dispersed supported materials could be highly beneficial for real applications. In this work, we invented an on-surface synthetic strategy for generating highly loaded and well-dispersed nickel nanoparticles on nickel oxide supports (Ni/NiO). This on-surface synthesis is a two-step process involving the surface transformation of Ni(OH) into a layer of chain-like nickel pyrazolate [Ni(pz)] and an ultra-high-vacuum annealing process that evacuates the pyrazole and decomposes the Ni(OH) into the Ni/NiO hybrid. The highly dispersed Ni/NiO catalyst exhibited superior activities and long-term stability for both the urea oxidation reaction and the hydrogen evolution reaction, which enables efficient urea electrolysis with a single catalyst. This approach presents a novel on-surface synthetic strategy for metal oxide-supported materials and offers efficient catalysts for advanced urea-assisted hydrogen production.