Multicomponent attachment to II-VI nanorods and their hierarchical assembly
thesisposted on 2022-09-06, 11:55 authored by Catriona O'Sullivan
This thesis describes the sequential assembly of various components on to colloidal II-VI semiconductor nanorods. Semiconductor-semiconductor, semiconductor-metal and semiconductor-metal-molecule are attached to the nanorods via solution phase techniques. Hierarchical (2-D) assemblies are obtained by pre-assembling the nanorods into perpendicularly aligned arrays with sequential attachment of the desired component (metal, molecule) occurring site selectively. Chapter 2 discusses the post synthetic, solution based end to end assembly of CdS, CdTe and Ag2S nanorods via the addition of octylamine. This spontaneous room temperature reaction led to the ttachment of nanorods, which were a controlled multiple of the starting length, up to a maximum final length of 160 nm. Chapter 3 discusses rapid gold tip formation on CdS, CdSe and CdTe nanorods via a precursor modification to an established solution based technique. Controllable gold tip sizes from 1 to 40 nm were achieved on CdSe nanorods while tip sizes up to 15 nm were achievable onto CdS and CdTe nanorods. The gold tip size, facet dependency and the multiplicity was controlled by the initial concentration of the gold complex and the reaction temperature. In Chapter 4, a spin cast technique is shown to achieve gold tip growth onto a pre-deposited perpendicularly aligned nanorod array resulting in hierarchical assemblies of gold tipped nanorods over centimetre scale. Gold tips smaller than the nanorod diameters occur spontaneously with gold nanocrystal size tunable with a change in precursor concentration or reaction duration. More complex three component semiconductor-metal-molecule assemblies were subsequently formed as discussed in Chapter 5. Here a model protein, cytochrome c, was immobilised onto each gold tip in the perpendicularly aligned array via a thiol linker. Confirmation that the process was functional was achieved via cyclic voltammetry (CV).