Synthesis Of Carbon Nanotubes And Their Electrocatalytic Properties For Alcohol Electrooxidation

Due to its specific physical and chemical properties, excellent electronic conductivity, superior resistance to corrosion and high thermal stability, Carbon naotubes have been widely used as catalysts, catalytic support, semiconductors, hydrogen storage materials, super capacitors and other fields. Carbon nanotubes exhibit broad application foreground and arouse research storm. Carbon nanotubes conventionally can be synthesized by CVD method, and fabricated by controlling the experimental parameters, such as used catalysts, carbon sources, reaction temperature and time. Among these parameters, the chemical components and structural characterof utilized catalyst is the most important factor in the formation of carbon nanotubes. The difference of catalyst effect the morphology and structure of carbon materials, ultimately lead to differences in application.Layered double hydroxides (LDHs) is a kind of highly ordered two-dimensional layered materials, consist of positively charged layers and negative anions in the interlayer. The metal ions in layers are uniformly distributed on an atomic level without segregation, which guarantees complex metal oxides obtained from calcined LDHs remain the same highly ordered arrangement as the precursors. Therefore, multi-walled carbon nanotubes with uniform diameter and high graphite degree were synthesized via the CVD method over complex metal oxides in quartz reactor.This thesis proposed a new method to synthesize carbon naotubes over LDHs precursors on the basis of advantages of adjustable variability and uniformity. Introduced Co, Cu, Mg metal species to the layer, M2+-M3+-LDHs are fabricated as the activite function precursors. Carbon nanotubes were synthesized over active Co nanoparticles derived from calcined products by CVD methods.(1) Investigation of Cu doped Co-based Carbon NanotubesA range of LDHs precursors with different Co2+/Cu2+ ratio were prepared via single drop method. Multi-walled carbon nanotubes were successfully grown from different LDHs precursors and different growth atmosphere by the CVD method. The effect of Cu doped quantity and growth atmosphere over morphology and yield was detailed studied. The results revealed that Cu doped quantity affected morphology character of CNTs, and growth atmosphere influenceed the yield and graphite degree of CNTs. The morphology of CNTs was successfully controlled via this method. (2) Investigation of Mg doped Co-based Carbon NanotubesA series of LDHs precursors with different Co2+/Mg2+ ratio were prepared via urea decomposition method. High yield carbon nanotubes were obtained catalytically by active Co nanoparticles derived from reducing calcined products. The effect of Mg doped quantity over morphology and yield was detailed investigated. The results indicated that the obtained CNTs possessed high yield, uniform outer diameters, regular morphology and high graphite degree. This method is simple and environmentally friendly, can be industrially applicated.Catalytic properties of carbon nanotubes for alcohol electrooxidation were systemly investigated. The Pt/CNTs composite electrocatalysts were designed with grown Co-based Carbon nanotubes as catalytic supports. As working electrodes, the designed Pt/CNTs composite electrocatalysts showed excellent electrocatalytic activity and strong anti-poisoning capability for methanol and ethanol electrooxidation. The Pt/CNTs composite electrocatalysts with different Cu and Mg doping quantity, displayed Significantly different catalytic activity. Finally, catalytic mechanism of alcohol oxidation was proposed.