Performance Study Of Pulse Electrodeposition Of Nanocrystalline Nickel And Its Alloy On Glassy Carbon Materials

This paper adopts the new glassy carbon material as the base, using periodic reversaldouble pulse method, electrodeposition on glassy carbon materials nanocrystalline nickeland Ni-W alloy, focused on the influence of pulse process parameters on themicrostructure of nanocrystalline nickel and Ni-W alloy, the electrochemical propertiesand the average grain size, etc. Through the experiment test to determine the best processconditions, under these conditions preparing catalytic materials of dense surface and goodperformance.Electrochemical and X-ray diffraction (XRD) test reveal that the optimum processconditions were NiSO4·6H2O300g/L、NiCl2·6H2O45g/L、pulse current density for anaverage of70mA/cm2, pulse duty ratio30%, the pulse frequency1000Hz, pH1.5, andtreatment temperature of55℃.Dense smooth, continuous uniform electrical layer has been developed, the structureis typical face-centered cubic (FCC), crystal(111) and (200) preferential growth, formationof about20nm clusters. Meanwhile, the average particle size is the smallest and latticeparameters are unchanged. Analyzing and estimating the mechanism of glassy carbonmaterial electrodeposited nanocrystalline nickel and the mechanism of electro-catalyticoxidation of methanol.According to the results of experiments, the following conclusions were obtained:glassy carbon material pulse electrodeposited nanocrystalline Ni-W alloy optimumconditions were NiSO4·6H2O15g/L、Na2WO4·2H2O30g/L、pulse current density for anaverage of100mA/cm2, pulse duty ratio30%, the pulse frequency100Hz, pH7, andtreatment temperature of55℃.The X-ray diffraction(XRD)、Energy Dispersive Spectrometer(EDS)、Transmissionelectron microscope (TEM)、scanning electron microscope (SEM) analyses confirmed thatNi-W alloy codeposition has been realized, and W content is relatively large,electrodeposited layer is more dense smooth, continuous and uniform. Compared withpure Ni, Ni-W alloy selected area electron diffraction ring from sparse diffraction point gradually became even and dense diffraction ring, which are corresponded to the changeof reducing particle size of crystal grain. Ni-W alloy occurred in2θ diffraction angle offsetand a diffraction peak close to Ni, formed a displacement of solid solution structure of Nifor solvent and W for solute, and structure of Ni is still typical FCC, so that by introducedW can not change the structure of Ni.Further analysis of the deposition behavior in Ni, Ni-W alloy under the optimalconditions, and the catalytic mechanism was carried out by means of cyclicvoltammograms curve as well as Ac impedance spectra. In the study of sedimentarymechanism Ni-W alloy is about4times redox peaks than that of pure Ni, which was moreconducive to the generating catalyst. Compared with pure Ni, Ni-W alloy has been foundabout3times beyond it in the performance of electric catalytic oxidation of methanol. ACimpedance curves of Ni, Ni-W alloy shows high frequency part of the semicircleotherwise, low frequency part of the straight line, the difference is Ni-W alloy acquires asmaller impedance value than pure Ni, thus perparation Ni-W alloy has more excellentperformance.