Manipulating the nickel shape and catalytic performance: from spheres to chains to urchins

Different nickel particle morphologies, including spheres, chains and urchins, were achieved in ethylene glycol solvent upon simply tuning both the amount of water and NaOH. The synthesis route was based on a routine solvothermal technique, in which nickel chloride and hydrazine hydrate were the nickel source and reductant, respectively. The shape transformation might be induced by an accelerated reaction rate and a change of the polarity of the solvent. Owing to the various morphology, these three kinds of nickel particles presented different catalytic performance. The reduction of 4-nitrophenol by NaBH4 as a typical catalytic model revealed that the urchin-like nickel particles behaved with the highest catalytic effect because of their unique structure with tips on the surface, which endowed much more active sites for the catalytic reaction. The good magnetic properties allowed these nickel particles to be readily recycled after application and they presented a much high cycling stability.