Graphene And Single-walled Carbon Nanotubes: Separation, Photo-and Electrocatalytic Properties

Graphene and single-walled carbon nanotubes (SWNTs) are close relatives of novel carbon nanomaterials. Because of their peculiar physical and chemical properties, both Graphene and SWNTs have potential applications in such fields as new energetic materials, catalysis and quantum computer etc., attracting great interest of scientific community. In this dissertation, we focused on the synthesis, separation, photo- and electrocatalytic properties of graphene and SWNTs, carrying out the following works:1. Synthesis of graphene and grapheme-modified Bi₂WO₆ as an improved photocatalyst. A new and improved photocatalyst (reduced graphene oxide (RGO)-modified Bi₂WO₆ (Bi₂WO₆-RGO)) was synthesized by a two-step hydrothermal process. The effect of RGO content on photoactivity was investigated and the optimum weight ratio of RGO to Bi₂WO₆ was determined to be 1% (w). Based on scanning electron microscopy, RGO does not change the structure and morphology of the Bi₂WO₆ photocatalyst. Therefore, the improvement in the photoactivity of the Bi₂WO₆-RGO composite is undoubtedly because of RGO. The presence of graphene can facilitate the dissociation of photogenerated excitons, which leads to more O₂^·- to degrade dye pollutants like rhodamine-B (RhB). Moreover, the efficient adsorption of RhB molecules on graphene is another reason for the improved photoactivity.2.Separation and electrocatalytic study of metallic and semiconducting SWNTs. Pristine SWNTs are always the mixture of metallic and semiconducting SWNTs, and their separation is crucial for the applications of SWNTs. SWNTs synthesized by arc-discharging method were pre-purified and then dispersed by sodium dodecyl sulfate (SDS) in water. Then the mixture was treated by using of agraose gel chromatography, affording the successful separation of metallic and semiconducting SWNTs, which was confirmed by UV-vis absorption and Raman spectroscopies. The purity of the separated metallic (M-) and semiconducting (S-) SWNTs is estimated to be 58.2% and 95.5%, respectively. Finally the separated M- and S-SWNTs were used to modify the glass carbon electrode so as to study their electrocatalytic property towards the oxidation of dopamine, for which the dominant role of M-SWNTs was revealed.