Bimetalik ve çekirdek-kabuk Au-Ag nanoparçacıkların spektroskopik karakterizasyonu ve yüklenme/yük boşalması özellikleri

The purpose of this work, is to control and manipulate optical and electrical properties of bimetallic alloy and core-shell Au and Ag nanoparticles by optical spectroscopy and XPS respectively. Several objectives have been pursued in achievement of the goal. First goal is to investigate the tunability of optical properties of bimetallic Au and Ag alloy and core-shell nanoparticles due to changes in composition and geometry, and later on, to study the possibility of charge-storage on single metal particles, especially on gold and silver, and bimetallic alloy forms of the corresponding nanoparticles in solution. Within this framework, bimetallic silver-gold alloy and core-shell particles are synthesized, then their electron-storage capacities in aqueous media by introduction of borohydride is followed by spectral shifts in their surface plasmon resonance bands. Moreover, the parameters like composition, geometry, affecting the charging ability of particles are reported by means of optical spectroscopy as well. In addition, electron storing/releasing capacities of Au and Ag nanoparticles and their kinetics are investigated.In the second part, main focus is to control and manipulate optical and electric properties by surface modification with incorporating Au and Ag nanoparticles within dielectric shell (silica and titania). Therefore, small Au@SiO2, Ag@SiO2, and Ag@TiO2 core-shell nanoparticles with the metal core size ca. 5-7.5 nm and the shell size ca. 3-7.5 nm are synthesized and optical properties of these nanoparticles are investigated. These nanoparticles are also analyzed by XPS under external biasing to get further understanding of their charging capacities. Additionally, we investigated incorporating the metal nanoparticles within titania shell to provide enhanced photocatalytic activity through the metal core by means of increased charging capacity.