Plasmonic Nanoparticles for Enhanced Photocatalytic Efficiency

Solar energy has been considered as a promising alternative energy source due to the high abundance of solar spectrum comparing to other alternative energy sources. Recently, the solar-to-energy conversion technologies have been applied to various applications including the photocatalytic water splitting reaction using semiconductor as photocatalysts. However, most semiconductor photocatalysts have suffered with several drawbacks such as wide band gap energy which limits the photo-responsive range in ultraviolet (UV) light, fast recombination rate of photogenerated electron-hole pairs, and low charge transfer efficiency. Recently, noble metal nanoparticles have played the important role to improve the photocatalytic efficiency of photocatalysts due to their unique optical and electronic properties. Among all outstanding properties of noble metal nanoparticles, localized surface plasmon resonance (LSPR) have been applied to various kind of semiconductors due to their tunable plasmonic properties in visible to near-infared (NIR) region. This dissertation focuses on the synthesis and characterizations of noble metal-based nanoparticles for enhanced photocatalytic activity. The first study reports the simple and reproducible synthesis procedure of ultrathin silica-coated hollow gold-silver nanoshells (GS-NS@SiO2) with controllable silica shell thickness. The LSPR extinction peak of hollow gold-silver nanoshells (GS-NS) are tunable in the range of visible to NIR region (500 – 900 nm). Furthermore, this dissertation also presents the method for coating zinc oxide (ZnO) shell on the as-prepared GS-NS@SiO2 to broaden the photo-active range of ZnO from UV to visible region. Additionally, gold nanoparticles are also reported to broaden the photo-responsive range of photocatalyst in the specific range of light. The third part of this dissertation describes the synthesis of gold-decorated metal alkaline earth titanate (MTO) nanoparticles, barium titanate (BTO) and strontium totanate (STO) nanoparticles with various photo-responsive range. All the as prepared nanoparticles described in this dissertation including silica-coated GS-NS, BTO@Au and STO@Au nanoparticles, and GS-NS@SiO2@ZnO nanoparticles, are considered as promising materials to enhance photocatalytic activity of various photocatalytic reactions.