Preparation And Applications Of Metal And Alloy Nano- Composites On Graphene

Graphene is a kind of carbon materials with a 2-D honeycomb crystal structure by packing monolayer of carbon atoms together densely which shows excellent properties such as high thermal conductivity and carrier mobility, great Young Modulus and specific surface area, ferromagnetic property and so on. Due to its unique nanostructure and extraordinary properties, grapheme-based materials have promising applications in optics, magnetic, biomedicine, catalysis, energy storage etc. In this thesis, we used the pre-treated graphene oxide to synthesize graphene-based nanocomposites. The growth mechanism and properties of our products were also studied. The main contents are as follows:1. The preparation and application of graphene-PtCu nanocomposites. We developed a novel one-step method to obtain a high dispersion of Pt and PtCu nanoparticles on graphene. By using both the carrier function and the reducibility of graphene. This method opens up a general route and feasible way for the synthesis of different alloy such as Pt-Ni and Pt-Cu-Ni on graphene sheets for applications in different functional nanoscale devices. Furthermore, this graphene-PtCu composite exhibits superior electrochemical activity and high poison tolerance toward methanol oxidation compared to graphene-Pt and commercial graphene-Pt composite, which demonstrates that the graphene-PtCu can be used as promising catalysts for direct methanol fuel cells.2. The preparation of graphene-PtNi nanocomposites and their catalytic application for preparation of carbon nanotube arrays. Graphene oxide was also used as substrates, and the Pt-Ni nanocomposites were used as the catalyst to synthesize graphene-CNT nanocomposites. The precursors of graphene-Ni and graphene-Pt-Ni were prepared by the same route in chapter 2, then they were used as the catalysts for the decomposition of C2H2, which lead to the growth of CNT on graphene substrates. The graphene-CNTs also displayed supercapacitor performances.3. Exploration of green methods for the preparation of graphene. Traditional synthesis methods of graphene always use the high temperature and strong oxidant via the chemical reduction process from graphene oxide in tough conditions. The production of graphene of other methods such as CVD are very low. Therefore, to explore methods to get larger yield by simple green synthesis of graphene is very important. In this chapter the intercalation of graphite was achieved by using specific green intercalator without adding any strong oxidant.