Synthesis, characterisation and applications of bimetallic nanoparticles

Abstract

The use of nanostructured materials has increased over the past decades and is attracting much attention. This has led to much enthusiasm in their studies across disciplines in chemistry, physics and biomedicine. Gold nanoparticles find applications in catalysis, as biosensors and cancer therapy, based on their optical properties. Fabricating nanoparticles comes with challenges such as control of size and shape which entails choosing fabrication methods carefully. There are various methods for fabricating and characterising nanoparticles and their alloys. This project has employed the versatile wet chemical synthesis to fabricate high aspect ratios, high yield gold nanorods and core-shell Au-Metal NRs. Powerful experimental techniques viz. UV-Vis NIR spectroscopy and electron microscopy (STEM) were employed to characterise the monometallic and bimetallic AuNRs. AuNSs, AuNRs, Au@Pd NRs, Au@Pd NSs, Au@Pt NRs and Au@Rh core-shell nanorods were synthesised and characterised by one or both of the methods mentioned above. The core-shell structures of gold with other precious metals studied in this work leads to enhanced electro-catalytic activity, which make them applicable to the DFAFCs and DMFCs to generate power for portable electronic devices. These core-shell nanoparticles have proved to be CO tolerant in the electro-oxidation of methanol and formic acid investigated in this project. Au@Rh has proved to be a good catalyst for oxygen reduction. This can make Rh a possible substitute for Pt in ORRs.