Abstract:
Noble metal nanoparticles were synthesized by either nucleation in solution or dewetting from thin metal films, and further oxidized to create a thin surface oxide shell. A detailed analysis of surface oxidation of noble metal nanoparticles is presented in this dissertation. This study allowed for utilizing these nanoparticles with controlled surface oxide to result in the growth of graphene shells around noble metal nanoparticles in a chemical vapor deposition process. Oxidation kinetics of noble metal nanoparticles was studied by combining electron microscopy and x-ray photoelectron spectroscopy techniques. This was further correlated with the growth of graphene shells and thicker oxide shell resulted in larger number of graphene layers. In regard to explore their applications, graphene shells encapsulated nanoparticles were demonstrated as a unique plasmonic substrates and catalytic substrates. Plasmonic modeling was done by discrete dipole approximation, simulated and explored the optical properties of graphene shells encapsulated noble metal nanostructures. This approach of graphene shells growth around noble metal nanoparticles was further exploited to understand the role of catalytic noble metal morphology and thus, detailed investigation of the CVD growth of graphene shells around segmented nanowire system was conducted. It was observed that graphene shells were grown around metal nanowires. However, the melting of the nanowires during the growth process must be carefully controlled. This further lead to complex nanowire heterostructures and their incorporation into polymer for bio-applications as demonstrated in this dissertation.
