Advanced Nanomaterial Composites for Enhanced Photocatalysis and Sensing

Recent advances in Nano structuring techniques have contributed to the field of plasmonic in recent years. In current research, plasmonic plays an important role in sensing, including surface enhanced Raman pectroscopy (SERS). The aim of the thesis is to investigate the combination of semiconductors and plasmonic nanomaterials in order to develop new designs. The combination of plasmonic nanomaterials with semiconductors has great potential for sensing and photocatalysis. This thesis is divided into nine chapters. We discuss the fundamentals of spectroscopy and photocatalysis, and the primary fabrication techniques for substrates in Chapters 1 and 2. In Chapter 3, we present a brief overview of the major spectroscopy and microscopy techniques utilised to explore the optical properties and morphology of manufactured substrates investigated in this thesis as well as the methods utilised to analyse the data. The analysis methodology and experimental specifics of how the measurements were conducted are described in some depth in the text, which presents the overall ideas underlying the analysis. In Chapter 4, we investigate the photocatalytic potential of transition metal chalcogenides (TMCs) cadmium sulphide (CdS) when coupled with plasmonic nanostructures. The synthesis of dimercaptoazobenzene (DMAB) from p-amino thiophenol (PATP) was demonstrated by the super bandgap irradiation of a silver nanowire (Ag NWs) and cadmium sulphide (CdS) composite for PATP. For plasmonic photocatalysis applications, our findings indicate that cadmium sulphide (CdS) can serve as an alternative to semiconductors, such as titanium dioxide. In Chapter 5 a combination of conducting polymers such as P3HT (poly 3 hexylthiophene) and PcBm (phenyl-C61-butyric acid methyl ester) with plasmonic nanomaterials is demonstrated to enhance Raman scattering spectroscopy signals up to five-fold and to support the oxidation of target molecules by supporting the charge transfer. The purpose of this chapter is to demonstrate how conducting polymers can be used as semiconductor platforms for the development of plasmonic catalysis and sensing techniques. Chapter 6 describes the development of nanocomposites consisting of metals and organic conducting semiconductors, which have the potential to provide a flexible, lightweight platform for plasmon-based sensing. The purpose of this chapter is to demonstrate the use of super band-gap irradiation to provide plasmon excitation and irradiation to remove analytes from a polymer-plasmonic composite based upon the conducting polymers P3HT and PCBM, as well as to support plasmon-enhanced spectroscopic detection. Our research demonstrates that such a polymer-plasmonic composite is an effective self-cleaning substrate for use as a reusable optical sensing substrate. In Chapter 7, plasmon active metal nanostructures and semiconductors are described as nanocomposites that support catalytic activity. As discussed in this chapter, transition metal dichalcogenides such as (MoS2) when combined with metal oxides such as (ZnO) have the potential to control charge states in plasmonic nanomaterials. The objective of Chapter 7 is to demonstrate the possibility of controlling plasmonic reactions through the careful selection of semiconductors. In Chapter 8, we present a framework consisting of silver nanoparticles (Ag NPs) on Mg-doped lithium niobate surface. The activation of charge transfer processes on this substrate under white light irradiation is demonstrated to support the oxidation of compounds such as p-amino thiophenol. The purpose of this chapter is to highlight the use of doped lithium niobate materials as semiconductor platforms for plasmonic catalysis. Conclusions and future work are discussed in Chapter 9.