Supercritical Fluid-Asisted Fabrication Of Ru/Graphene Composites And Graphene/Polystyrene Foams:Effect Of Interaction

Graphene has remarkable electronic properties, excellent chemical stability and large specific surface area, thus it is a great candidate for metal loading and polymer heterogeneous nucleation. However, how the surface properties of graphene influences metal loading and fully realizes the acitivity of the composites is not explored. Besides, the efficiency of graphene as heterogeneous nucleation substrate is not fully understood.In this thesis, using graphite as starting materials, we synthesized graphite oxide (GO) by Hummers method and heat reduced graphite oxide (HRGO) through themal reduction. GO and HRGO were characterized using FT-IR、TG and elemental analysis and surface functionalization graphene and graphite oxide were performed. After oxidation, graphite contain large amounts of oxygen and HRGO recover conductivity..Using graphene oxide and RuCl3as precurors, we successfully fabricated ruthenium/graphene nanocomposites with the aid of supercritical water. We also used thermally reduced graphene as a carrier. XRD、EDS and TEM were used to investigate the morphology of the composites or metal loading. The intermolecular interactions betweens the surface of graphene and Ru nanoparticles were investigated by XPS and FT-IR. The hydrogenation of benzene and cyclohexene are demonstrated the activity of composites. Compared with HRGO, the composite fabricated by graphene oxide had40wt%loading, and shown excellent catalytic performances, which were closely associated with the interfacial interaction between Ru and graphene.With graphene oxide, graphite, carbon nanotubes, functionalized graphenes, directly exfoliated graphene and hybrid grahenes as fillers, composites were prepared by solution blending-flocculation-molding preparation. Compared with pure PS, form morphology was improved due to the heterogeneous nucleation effect of different fillers in foaming process, resulting in a microcellular structure with smaller cell size and higher cell density under facile foaming conditions. HGs were parpared by a graphene oxide and carbon nanotubes mixture, FGs were functionalized in styrene by sonochemistry, DEG was prepared by direct exfoliation of graphite with aid of ultrasonication. The foams generated from those reinforced composites shown differences in micocelluar size and pore density as confirmed by SEM. The effect of filler surface chemistry on foaming in composite was investigated, showing that oxygen-containing surface leaded to a smaller pore size reduction. CNT, FGs and DEG gave nearly identical excellent nucleation foaming effects. HGs-1and HGs-2show bimodal cell structure polystyrene foams uing scCO2, and the heterogeneous with different sturcture have different nucleation mechanism.