Study On The Preparation And Electrochemical Properties Of Ru/CMSs Composites

As an environmentally friendly cell of energy conversion, direct methanol fuel cells (DMFC) have been considered to be a power source for portable electric devices, because of the high energy conversion rate, no pollution, no noise and high energy density. However, the complicated preparation and structure of the catalysts and supporters affect the efficiency of the cell. Carbon micro-spheres (CMSs), which have excellent properties and potential applications because of their special structures, are nanomaterials similar to fulluences with cage structure. They are important members of carbon family. According to their structural characteristics, carbon micro-spheres can be classified as solid carbon micro-spheres (SCMSs) and hollow carbon micro-spheres (HCMSs). Many potential applications for CMSs have been proposed, such as anode material of secondary lithium ion batteries, catalyst supporters, fillers in composite, porous conductive and super-high hydrogen storage materials. Their good chemical properties and electric conductivity made them promised as catalyst supporters.In this paper, with acetylene as carbon source, SCMSs were prepared by chemical vapor deposition (CVD) and chemically modified for introducing new functional groups onto their surface. The as-treated CMSs got sensitized in SnCl2 solution. And then Ru nanoparticles were deposited on the surfaces of activated SCMSs by electroless plating. The influences of modifications and the contents of SnCl2 and RuCl3 on the products were discussed. And then DOA was chosen as carbon source, Ru/HCMSs were prepared by the same method. The morphology and structure of the samples were characterized by field emission scanning electron microscopy, high resolution transmission electron microscopy, fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and thermogravimetry. Then electro-catalytic properties of Ru/SCMSs and Ru/HCMSs were characterized and compared by electrochemical methods.The main conclusions are as follows:1. The influence of air oxidation, H2SO4/K2Cr2O7 and HNO3/H2O2 mixed acid oxidation methods on CMSs was investigated. The results show that: modified by air oxidation under 400℃, SCMSs homogeneously loaded Ru nanoparticles. Then the effects of the contents of SnCl2 and RuCl3 on samples were discussed, showing that uniform Ru nanoparticles with ~15 nm in diameter on the surface of CMSs were obtained with 0.5 mmol/L of SnCl2 and 5 mmol/L of RuCl3.2. Electrochemical analysis shows that Ru/CMSs were the composites with catalytic activity, although the catalytic properties remain to be explored. HCMSs could be applied in capacitance as supporter of electrode, owing to their higher specific surface area. The good capacitivity shown by Ru/CMSs composites in acidic solution indicated the promising application in capacitance and catalysis.