Transition Metal (Nickel?Copper) And Composites:Synthesis And Catalytic Performance

The transition metal nanomaterials have been widely applied in many fields, such as energy, sensing and catalysis, owing to their unique physical and chemical properties. The nickel and copper-based nanomaterials appeal great research interest and present important value in the fields of catalysis and electrochemical, because of their abundant storage and low cost. The composition, morphology and size are the key factors in determining the performance and applications of nanomaterials. Recently, the researchers have prepared a series of nickel and copper-based functional nanomaterials with specific morphologies and high-performance through finely designing and manufacturing the materials along with the development of nanotechnology. The research on the performance and application of nickel and copper-based nanomaterials has received significant progresses. In this paper, we prepared different morphological nickel nanoparticles and copper-based nanocomposite through different strategies, and studied the catalytic activity of two products by using the reduction of 4-nitrophenol ?4-NP? with sodium borohydride as a model catalytic reaction. The main contents are as follows:1. The synthesis route was based on a routine solvothermal technique, in which nickel chloride and hydrazine hydrate were the nickel source and reductant. respectively. 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. We found the synergistic effect of the above two factors played important role in controlling the surface, shape and size of the obtained nickel particles. We considered the former one effectively changed the polarity of the solvent that changed the dipole-dipole interaction between the nickel nuclei and the later one greatly accelerated the reaction rate that resulted in a kinetic controlled process. The reduction of 4-NP by NaBH₄ in aqueous media was selected as a model reaction to evaluate the catalytic performance of the different nickel particle morphologies, and the results revealed that the urchin-like nickel particles behaved with the highest catalytic effect because of their unique structure. Owing to the good magnetic properties of these nickel particles, the samples were allowed to be readily recycled after application and they presented a much high cycling stability.2. Highly dispersible copper nanoparticles ?CuNPs? supported on the N-doped carbon films were achieved by pyrolyzing urea, citric acid ?CA? and copper nitrate in one pot. The as-obtained samples were investigated by transmission electron microscopic, X-ray diffraction, X-ray photoelectron and Raman spectra. The citric acid was used as a carbon source to support the as-synthesized CuNPs owing to the presence of many hydrophilic groups ?-OH and -COOH? on the surface of Cu-NCF originated from CA. The urea released NH₃, CO₂ and H₂O gases during the carbonization process, which was favourable for the formation of nitrogen doped carbon film. The introduction of N species in the carbon materials could improve the electrical conductivity of the sample. Furthermore, such an N-doped carbon film with well-dispersed CuNPs on its surface exhibited excellent catalytic performance and cyclic stability for 4-NP reduction reaction.