Synthesis And Performance Research Of Ni And Ni-based Nanomaterials

In view of current study on Nickel(Ni)and Ni-based nanomaterials is a promising topic in the nanomaterials,we designed simple solid-liquid phase chemical routes to controllably synthesize metal Ni nano particles with different phase structure,Ni-basesd nanoalloy(e.g.Ni-Ru)and nickel sulfides(e.g.NiS,Ni2S3).We also studied the catalytic hydrogenation of nitrophenols reduced by NaBH4,electrocatalytic performance of hydrogen evolution reaction(HER)and electrocatalytic performance of oxygen reduction reaction(ORR).The detailed achievements are given below:(1)By using 1-octodecene(ODE)as solvent,terpilenol and dodecylamine(DDA)as capping reagent and nickel formate(Ni(COOH)2)as the source of Ni,the face centered cubic(fcc)and hexagonal close packed(hcp)Ni NPs were synthesized successfully by only changing the temperature during the reaction.The synthesized fcc and hcp Ni nanopaticles are both 60-80 nm and the morphology are similar.The obtained fcc and hcp Ni nanoparticles both showed great activity in the catalytic hydrogenation of nitrophenols(2-nitrophenol,3-nitrophenol and 4-nitrophenol)when reduced by NaBH4,and the catalytic activity of hcp Ni nanoparticles are much stronger than that of fcc Ni nanoparticles.With the analysis,we consider that the higher catalytic acivity of hcp Ni nanopaticles is coming from the more available active sites in the surface of hcp Ni nanoparticle than in fcc Ni nanoparticles.The stability tests showed that after 10 times recycle experiments the catalytic activity have no obvious loss both for fcc Ni and hcp Ni nanoparticles.(2)When using ethylene glycol(EG)as solvent,Ni nanochains as Ni resource,and RuCl3·3H2O as Ru resource,we synthesized necklace-like hollow NixRuy nanoalloys sussessfully.According to the standard electrode potential of Ru3+/Ru couple and Ni2+/Ni couple,and the physical characterization,we can know that the hollow Ni cores was generated due to the Kirkendall effect and the initial Ni nanochains are served as the sacrificial template.At the same time,the reduced Ru(0)atoms will spontaneously deposit on the surface of the hollow Ni cores,and the large lattice mismatch between Ni and Ru as well as their differences on bond dissociation energies provide driving force for the diffusion of Ru atoms into Ni lattice to form necklace-like hollow NixRuy nanoalloys.Electrochemical tests reveal that in contrast to pure Ni and pure Ru nanostructures,those NixRuy nanoalloys show greatly enhanced electrocatalytic activity and stability for HER in acid media.Among the NixRuy nanoalloys,Ni43Ru57 exhibits highest catalytic activity,which is close to commercial Pt/C.(3)By using nickel nanocrystals with different phase(fee and hcp)as seeds and Ni resource,we studied the chemical reactivities of the fee and hcp Ni nanoparticles in the synthesis of nickel sulfide.Two different reaction systems were employed.In the first reaction system,trioctylphosphine(TOP)is used as capping agent and ODE as the solvent.The results showed that the nickel sulfides with different phases will be obtained when reacted in the same experiment condition for fee and hcp Ni nanocrystals.With a series of analysis,we found that in this system fee Ni nanoparticles were more reactive than hcp Ni nanoparticles,which leading to the different nickel sulfides.In the second reaction system,EG is used as capping agent and solvent.The results showed that the nickel sulfide with same phase will be obtained when reacted in the same experiment condition for fee and hcp Ni nanocrystals.With a series of analysis,we found that in EG system,fee Ni nanoparticles have the same reactive feature with hcp Ni nanoparticles.We also tested the ORR performance of these nickel sulfides.