Synthesis and Catalytic Properties of Binary Core Shell Coinage Metal s Nanostructures

Abstract

The work presented in this thesis enlightens the significance of coinage bimetallic (BM) nanocomposites (NCs) over their monometallic counterparts. Main emphasis has been given to the synthesis of BM NCs in the form of coreatshell alloy and hollow nanostructures by varying the nature of core, shell composition and composition, their characterization, and application to catalysis and co-catalysis. This whole work is divided into six chapters which are described below: Chapter 1: Introduction and Literature: The first chapter provides the brief introduction on the need of BM NCs over monometallic NPs which have been emerging as important catalyst due to the synergistic effects between the two metals. A brief description of preparation strategies for coreatshell, alloy and hollow BM NCs and various techniques used for the characterization of optical, electrokinetic, catalytic and co-catalytic properties of BM NCs relative to their monometallic counterparts have also been incorporated. Chapter 2: Improved Catalytic Activity and Surface Electro-kinetics of Bimetallic Au-Ag Core-Shell Nanocomposites: This chapter demonstrates the preparation of coreatshell NCs of AuatAg and AgatAu for measuring their catalytic activity and electro-kinetic properties relative to their respective monometallic counterparts. A significant blue-shift (530 to 408 nm) and red-shift (420 to 550 nm) of the surface plasmon (SP) band for AuatAg and AgatAu NCs, respectively, was observed due to increased size of binary composites depending on the nature of core and shell material. The thickness of the deposited Ag shells varied from ~3-10 nm on Au core leading to the formation of AuatAg NCs. On the other hand, the Ag core served as a sacrificial template, where AgatAu NCs was converted to hollow Ag-Au alloy shells (~15 nm) because of the galvanic reaction between them due to the difference in their redox potential.