The Synthesis And Application Study Of New-type Metallic Graphene Nanocapsules

Graphene has been widely researched in catalysis, photoelectricity and Raman fields owing to two-dimension carbon network, high specific surface area,excellent mobility of charge carriers and Raman performance and so on. Metal nanoparticles also play good performance in the those fields due to nano-size and different morphology. Generally,we fabricated metallic graphene nanocomposite by some ways to enhance the catalytic activity and stability of metal nanoparticles. Based on the above excellent performance and disadvantages, this paper prepared a new noval metallic graphene nanocomposite by chemical vapor deposition, to expoler the development of its properties for catalytic activity, stability and SERS. The main contents of this thesis are as follows:?1? We have synthesized a graphene-encapsulated Pt nanocrystal?GPN? through a simple chemical vapor deposition?CVD? method. Furthermore, to further improve their catalytic activity, a plasma-assisted nitrogen doping method was developed, and the nitrogendoped graphene-encapsulated Pt nanocrystal?N-GPN? also demonstrated efficient electrocatalytic activities, in fact much higher than those reported for conventional Ptgraphene composite catalysts due to their small particle diameter, uniform size distribution, sufficient graphene-Pt contact, and new generation of activation sites after nitrogen doping.?2? We fabricate an efficient and stable photocatalyst system which has superior recyclability even under concentrated acidic conditions. The photocatalyst is prepared by assembling magnetic graphitic nanocapsules, titania?TiO₂? and graphene oxide?GO? into a complex system through p-p stacking and electrostatic interactions. Such catalytic complex demonstrates very high stability. With methyl orange as the model molecule, the photocatalyst was demonstrated to rapidly decompose the molecules with very high photocatalytic activity under both concentrated acidic and neutral condition. Moreover, this photocatalyst retains approximately 100 wt% of its original photocatalytic activity even after multiple experimental runs of magnetic recycling. Finally, using different samples from natural water sources and different dyes, this GO/magnetic graphitic nanocapsule/TiO₂ system also demonstrates its high efficiency and recyclability for practical application.?3? We develop a simple chemical-vapor-deposition method to fabricate grapheneisolated-Au-nanocrystal with core-shell nanostructures. and a multifunctional surface enhance Raman scattering?SERS? substrates?ACT nanoparticles? prepared by Assembling Au-graphene nanocapsules and modified TiO₂ with APTES. Such SERS substrates exhibit superior SERS sensitivity with high reproducibility and stability. More importantly, our SERS substrates can clean themselves by photocatalytic degradation of the target molecules adsorbed to the substrates under simulated sunlight. Compared with single-use problems of traditional SERS substrates, This work provided a simple approach to fabricate SERS substrates with less cost. This substrates show high sensitivity and recyclability by detection Rhodamine 6G?R6G? dye and make a promise application in further SERS detection.