| Graphene, as a two dimensional sp2 carbon material with single-atom thickness, has received wide attentions since its first discovery in 2004 due to the unique structure and excellent optical, electrical, magnetic, thermal and mechanical properties. Important applications have been exploited in many areas such as microelectronics industry, catalysis, sensors, theranostics, energy transformation and storage. However, there still exist many problems that are urgent to be resolved during the usage of graphene:(1) new methods through which graphene is synthesized in large scale should be developed; (2) multifunctional graphene-based composites should be explored in order to expand or improve the performances; (3) the water-dispersity and biocompatibility as well as the interface properties of graphene should be improved by different modifications in order to meet requirements for biomedical application. Therefore, it is highly demanded to do some researches including large-scaled synthesis of graphene in low cost, the preparation of multifunctional graphene-based composites, and also the characterizations and applications of these new materials.In this work, the synthesis, characterizations and applications of graphene and its composites are our focus and also the main content, which can be divided into five parts as follows.(1) In chapter one, the main progress of graphene including the history, the structure, the properties, the synthesis, the modifications, the characterizations and applications was reviewed. Especially, the applications of graphene in energy transformation and storage, analytical chemistry and also biomedicine were expatiated in details. The research ideas and innovation points of this thesis were also suggested.(2) In chapter two, it was demonstrated that single graphene sheets can be easily synthesized in large amounts by using zeolite Ni-MCM-22 as a catalyst and template. The graphene had a large surface area, high conductivity, and controllable two-dimensional sizes. The usage of prepared grapheme in our work as supercapacitor electrode materials revealed excellent electrochemical double layer capacitance and galvanostatic charge/discharge properties with specific capacitances of 233 F/g in aqueous KOH.(3) In chapter three, hybrid nanomaterials (GAg) of graphene nanosheets and Ag nanoparticles (AgNPs) were prepared by a one-pot reduction of both Ag+ and graphene oxide (GO), and studied for electrochemical oxidation of methanol in alkaline solution. From results of TEM, XRD and other measurements, the crystalline AgNPs with a typical diameter of 5～15 nm were homogeneously decorated on graphene nanosheets without aggregation, while their densities (25.6%～61.0%) could be easily controlled by changing the synthesis ratio of graphene oxide nanosheets to Ag+. Cyclic voltammograms results revealed that the GAg materials had the increased electrocatalytic activity (reversed catalytic peak current:0.22×10-5 A～1.01×10-5 A) with the increase of AgNPs loading for methanol oxidation in alkaline solution, and the catalytic current was linear to the concentration of CH3OH. At last, the stability of GAg catalysts-modified electrodes and the influence of catalytic reaction temperature towards methanol oxidation were also investigated. The facile synthesis, low cost and high activity of the GAg materials endue them with great potential applications in the direct methanol alkaline fuel cells (DMAFCs).(4) In chapter four, targeting peptide-modified magnetic graphene-based mesoporous silica (MGMSPI) were synthesized, characterized, and developed as a multifunctional theranostic platform. This system exhibited many merits, such as biocompatibility, high near-infrared photothermal heating, facile magnetic separation, large T2 relaxation rates (r2), and a high doxorubicin (DOX)-loading capacity. In vitro and in vivo results demonstrated that DOX-loaded MGMSPI (MGMSPID) could integrate magnetic resonance imaging, dual targeting recognition (magnetic targeting and receptor-mediated active targeting), and chemo-photothermal therapy into a single system for a visualized-synergistic therapy of glioma. In addition, it was observed that the MGMSPID system possessed heat-stimulated, pH-responsive, sustained release properties. All of these characteristics could provide a robust multifunctional theranostic platform for visualized glioma therapy(5) In chapter five, the conclusions and the prospects for this work were summarized and proposed, respectively. |
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