Since Ni grain is one

of the most typical catalysts for carbon microcoil (CMC), it is necessary to synthesize uniform Ni particles with designed sizes and to study the effects on the preparation and growth mechanism of the Ni particles. In this study, we prepare Ni nanoparticles by reduction of nickel sulfate with hydrazine hydrate employing the surfactant Elacridar polyvinylpyrrolidone (PVP) to prevent agglomeration of particles. The as-prepared Ni particles were also used for the growth of CCFs. Methods Materials Nickel sulfate (NiSO4 · 6H2O, analytical reagent (AR)), PVP (K30, AR, average molecular weight 40,000), sodium hydroxide (NaOH, AR) and hydrazine hydrated (N2H4 · H2O, AR) were purchased from Chengdu Jinshan Chemical Reagent Limited Company, Chengdu, China. Acetylene (C2H2, 99.9%), nitrogen (N2, 99.999%), and hydrogen (H2, 99.99%) were purchased from Chengdu Liuhe Chemical Industry, Chengdu, China. All reagents were used without any further purification. Preparation of Ni nanoparticles Two kinds of solution were

firstly prepared. Solution A was formed by adding NaOH solution (0.8 to 1.5 M) in 20 ml hydrazine hydrated (6 M) with pH ranging from 10 to 14. Solution B was formed by dissolving 5.256 g of nickel sulfate (NiSO4 · 6H2O) in distilled water, which contained 1 g of PVP polymer as dispersant. Solution A was added selleck inhibitor to a beaker with a capacity of 100 ml and was magnetically stirred for 15 min at 60°C ~ 80°C. Then, slowly dropwise, adding solution B into A, it was stirred continuously for 45 min. The black precipitates were separated from the mother liquor by magnetic separation and washed repeatedly with distilled water

and acetone until the pH was 7. The grey-black powder was finally dried in vacuum at 25°C. Preparation of coiled carbon fibers The as-prepared Ni nanoparticles were used as catalyst for CCFs and dispersed on a graphite substrate by spraying and drying the suspension of Ni particles. Then CCFs were obtained on the graphite by catalytic pyrolysis of acetylene containing Cobimetinib manufacturer a small amount of thiophene as the liquid catalytic addictives. Acetylene, hydrogen, and nitrogen were introduced into a horizontal Epigenetics inhibitor reaction tube (quartz, 28 mm i.d.) which was heated from the outside by a tubular furnace. The flow rates of acetylene and nitrogen were fixed at 20 and 60 ml/min (sccm), respectively, and the hydrogen flow rate ranged from 100 to 140 sccm. Several kinds of CCFs grew exclusively on the upper region of the source gas steam. Characterization The crystal structure of catalyst particles and helical carbon fibers was investigated using X-ray diffraction (XRD with Ni filter, Panalytical X’Pert PRO diffractometer, Almelo, the Netherlands). The size and morphology analyses of nickel particles and CCFs were performed using environmental scanning electron microscopy (ESEM; FEI, Quanta 200, FEI Company, Hillsboro, OR, USA) with an accelerating voltage of 20.