Surface functionalisation techniques for colloidal inorganic nanocrystals

Colloidally-stable inorganic nanocrystals have a wide range of envisaged applications in biological environments. To reach their potential, the nanocrystals need to be stable in aqueous environments and have pendant functionality available for attachment of biomolecules. In this thesis, new methods for the transfer of nanocrystals from organic to aqueous media are developed and the interaction of aqueous stabilised particles with serum proteins is investigated. In Chapter 3, a new method for the synthesis of a thin silica layer upon the surface of nanocrystals is demonstrated. The method uses the hydrophobic interaction between an amphiphilic polymer and nanocrystal ligands to provide a foundation for growth of a silica layer. The coated nanocrystals are characterised using a wide range of techniques confirming that the presence and location of the silica shell. In Chapter 4, custom-synthesised amphiphilic polymers for water transfer and functionalisation of nanocrystals are synthesised, characterised and tested. Commercially-available polymers used for this purpose are examined, leading to a rationale for custom-design. Partial water transfers were achieved using activated ester copolymers with styrene but no transfers were achieved the octadecylacrylate copolymers. Poly(ethylene glycol) containing monomers were also used but yielded no transfers. This suggests that behaviour of the polymer during the coating procedure is intimately linked to the structure of the polymer. In Chapter 5, small-angle neutron scattering is used to elucidate structural information for the protein corona formed on nanocrystals and silica nanoparticles. Information on the packing of ligands on colloidal nanocrystals without a amphiphilic polymer coating was determined. The fitting of the protein corona upon silica nanoparticles was explored using core-shell form factors but was hampered by complexities within the scattering profiles which were not accounted for using simple form factors

Nickel-doped ceria nanoparticles : the effect of annealing on room temperature ferromagnetism

Nickel-doped cerium dioxide nanoparticles exhibit room temperature ferromagnetism due to high oxygen mobility within the doped CeO2 lattice. CeO2 is an excellent doping matrix as it can lose oxygen whilst retaining its structure. This leads to increased oxygen mobility within the fluorite CeO2 lattice, leading to the formation of Ce3+ and Ce4+ species and hence doped ceria shows a high propensity for numerous catalytic processes. Magnetic ceria are important in several applications from magnetic data storage devices to magnetically recoverable catalysts. We investigate the effect doping nickel into a CeO2 lattice has on the room temperature ferromagnetism in monodisperse cerium dioxide nanoparticles synthesised by the thermal decomposition of cerium(III) and nickel(II) oleate metal organic precursors before and after annealing. The composition of nanoparticles pre- and post-anneal were analysed using: TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), EDS (energy-dispersive X-ray spectroscopy) and XRD (X-ray diffraction). Optical and magnetic properties were also studied using UV/Visible spectroscopy and SQUID (superconducting interference device) magnetometry respectively

Novel Xanthate Complexes for the Size Controlled Synthesis of Copper Sulfide Nanorods

We present a simple, easily scalable route to monodisperse copper sulfide nanocrystals by the hot injection of a series of novel copper­(I) xanthate single-source precursors [(PPh₃)₂Cu­(S₂COR)] (R = isobutyl, 2-methoxyethyl, 2-ethoxyethyl, 1-methoxy-2-propyl, 3-methoxy-1-butyl, and 3-methoxy-3-methyl-1-butyl), whose crystal structures are also reported. We show that the width of the obtained rods is dependent on the length of the xanthate chain, which we rationalize through a computational study, where we show that there is a relationship between the ground-state energy of the precursor and the copper sulfide rod width

Synthesis of diaryl dithiocarbamate complexes of zinc and their uses as single source precursors for nanoscale ZnS

Diaryldithiocarbamate complexes, [Zn(S2CNAr2)2], have been prepared with a view to comparing their structures, reactivity and thermally-promoted degradation with respect to the well-studied dialkyl-derivatives. In the solid-state both [Zn{S2CN(p-tol)2}2] and [Zn{S2CN(p-anisyl)2}2] are monomeric with a distorted tetrahedral Zn(II) centre, but somewhat unexpectedly, the bulkier naphthyl-derivative [Zn{S2CN(2-nap)2}2]2 forms dimeric pairs with five-coordinate Zn(II) centres. Preliminary reactivity studies on [Zn{S2CN(p-tol)2}2] suggests that it binds amines and cyclic amines in a similar fashion to the dialkyl complexes and can achieve six-coordination as shown in the molecular structure of [Zn{S2CN(p-tol)2}2(2,2′-bipy)]. The thermal decomposition of [Zn{S2CN(p-tol)2}2] was studied in oleylamine solution by both heat-up and hot-injection methods. Nanorods of ZnS were produced in both cases with average dimensions of 17 × 2.1 nm and 11 × 3.5 nm respectively, being significantly shorter than those produced from [Zn(S2CNiBu2)2] under similar conditions. This is tentatively attributed to the differing rates of amine-exchange between diaryl- and dialkyl dithiocarbamate (DTC) complexes and/or their differing rates of DTC loss following amine-exchange. The solid-state decomposition of [Zn{S2CN(p-tol)2}2] has also been studied at 450 °C under argon affording irregular and large (10–300 µm) sheet-like particles of wurtzite

Copper-doped CdSe/ZnS quantum dots : controllable photoactivated copper(I) cation storage and release vectors for catalysis

The first photoactivated doped quantum dot vector for metal-ion release has been developed. A facile method for doping copper(I) cations within ZnS quantum dot shells was achieved through the use of metal-dithiocarbamates, with Cu(+) ions elucidated by X-ray photoelectron spectroscopy. Photoexcitation of the quantum dots has been shown to release Cu(+) ions, which was employed as an effective catalyst for the Huisgen [3+2] cycloaddition reaction. The relationship between the extent of doping, catalytic activity, and the fluorescence quenching was also explored

Black Phosphorus with Near-Superhydrophic Properties and Long-Term Stability in Aqueous Media

Black phosphorus is a two-dimensional material that has potential applications in energy storage, high frequency electronics and sensing, yet it suffers from instability in oxygenated and/or aqueous systems. Here we present the use of a polymeric stabilizer which prevents the degradation of nearly 68% of the material in aqueous media over the course of ca. 1 month

Shining a Light on Transition Metal Chalcogenides for Sustainable Photovoltaics

Transition metal chalcogenides are an important family of materials that have received significant interest in recent years as they have the potential for diverse applications ranging from use in electronics to industrial lubricants. One of their most exciting properties is the ability to generate electricity from incident light. In this perspective we will summarise and highlight the key results and challenges in this area and explain how transition metal chalcogenides are a good choice for future sustainable photovoltaics

Plasmonically enhanced electromotive force of narrow bandgap PbS QD-based photovoltaics

Promoted photocurrent generation results in an improved electromotive force by combining MEG-effective PbS QDs with LSPR-active Au nanoparticles.</p