The current energy crisis has driven the scientific research in a direction to find alternative options for fossil fuels. Solar energy is the most abundant and suitable for being the mainstream of the future renewable energy amongst other options. Therefore the research on photo-responsive material has been a major part of the solar energy related research. CNT/Ti02 nanocomposite as a promising candidate has attracted significant attention. In this thesis photoelectrochemical study was conducted in order to reveal the properties of the composites. A photoelectrochemical reactor was purposely designed and constructed for the current project after reviewing the design criteria and similar reactors in the literature. The composite synthesis procedure was improved in precision and consistency to ensure the product was more reproducible. The TEM, XRD and TGA data showed that the Ti02 precursors affected the thickness of the · Ti02 layer, the calcination characteristics and hence the CNT content of the final composite. The Ti02 layer was 5 - 10 nm thick and the crystallites were 8 - 10 nm in diameter depends on the type of precursor. A thinner Ti02 coating was found to be beneficial to the suspended photocatalyst whilst the conductivity of the composite was more important to the immobilised composite. It suggested that the CNT content was proportional to the photocurrent level generated and the acid-treated CNTs performed better than raw CNTs. The photocurrent increased significantly with positively increasing the applied potential for all the composites and substrates tested. The electrochemical aspects of the threeelectrode cell were discussed based on the suggested semi-quantitative model for charge transfer across the working electrode. It had shown that the synergetic effect between CNTs and Ti02 were important and strong. These results are valuable for tailoring the CNT/Ti02 or similar nanocomposites to meet specific technological applications in the environmental and renewable energy sectors. I

This work presents the development of an integrated instrument which incorporates two powerful techniques , the atomic force microscopy (AFM) and the polarised Raman micro-spectroscopy (PR~!lS), to determine the molecular organisation of the Phe-Phe (FF) micro- and nanotubes. The diphenylalanine peptidebased nanotubes consist of the FF molecules self-aggregated into a tubular structure exhibiting unique physical, chemical and biological properties. These prominent characteristics promote this nanomaterial to be a potential candidate for numerous applications. The FF peptide-based structure has also been studied extensively in medical research. This is because its self-aggregation mechanism plays a key role in the formation of amyloid fibrils , which are related to various diseases. Understanding such formation mechanism could provide new treatments for these diseases. The structural organisation of the FF tubes became a controversial issue because of the lack of direct evidence, especially at micro- and nanoscale. In this ~work , AFM and polarised Raman spectroscopy was used to determine molecular interaction and orientation for individual FF tubes. As the combined AFM-PRMS system consists of two essential parts operating individually, new control software was designed and developed to synchronise both instruments. Therefore, investigation of the selected FF tubes can be performed using polarised Raman micro-spect;~scopy. Simultaneously, the tube diameter can be measured accurately using the AFM. To determine the molecular organisation of the FF tubes , the studied began with the investigation of the FF samples by conventional Raman measurements for determining the observed Raman bands and their corresponding vibrational modes. Additionally, the DFT calculation was employed to confirm the band assignment. Finally, the polarised Raman micro-spectroscopy was used to determined the anisotropic properties of some key vibrational modes, particularly, the amide I and the amide III bands. The experimental measurements were carried out by two methods. In the first method. the FF samples was studied by investigating the variation of intensity of the selected Raman bands when the polarisation direction of excitation laser changed from 0° to 360° vvith respect to the tube axis. The probable orientation of the selected bands was depicted in polar diagrams of normalised Raman intensity. For the second approach, the FF tubes were investigated with four polarisation configurations using a half-wave plate and an analyser. A dataset of polarised Raman spectra corresponding to the selected bands was mathematically analysed using a uniaxial model to determine quantitatively the orientation distribution function (ODF). Both methods provided consistent results illustrating that the peptide C=O bonds of the FF molecule are preferentially aligned along the tube and the peptide backbone is aligned perpendicular of the tube. From the second method , the angle between the C=O bond and the tube axis was determined to be rv 8° in crystalline structure. Furthermore, the tubes of different diameter showed no noticeable variation in molecular organisation within the experimental error. As the calculation was dependent on various parameters, the uncertainty of the mean orientation angle was also assessed. II

The aim of the work described in this thesis was to investigate and exploit the properties of hydrogen bonded supramolecular self-assembled networks (SANs) through use as a template to pattern substrate surfaces at the sub 10 nm length scale. This would potentially allow control over the spatial distribution of molecules, and thus the chemical and biofunctionality of a surface at this length scale. Complementary surface analysis techniques were used throughout the project to characterise substrates functionalised with SANs and subsequent biomolecule adsorption including: atomic force microscopy (AFM), scanning tunnelling microscopy (STM), PeakForce QNM (PF-QNM), time of flight secondary ion mass spectrometry (ToF-SIMS), and X-ray photoelectron spectroscopy (XPS). A hydrogen bonded PTCDI-melamine SAN, previously investigated with UHV STM, was selected for these studies as a suitable candidate system to explore the biofunctionality of SANs. As AFM is the preferred SPM technique to obtain images of biomolecules the resolution capabilities of our AFM system were fIrst tested through the use of different imaging modes and tips, as well as two model systems. The fIrst model system used ferritin, a spherical protein with a diameter of ~ 12 nm, subsequently deposited onto a HOPG substrate. The AFM was able to successfully achieve resolution of individual ferritin molecules. The second model system used C60 fullerenes with a diameter of ~ 1 nm deposited onto a Si (100) substrate; the obtained AFM images showed features attributable to individual fullerene molecules. While STM regularly resolved the molecular structure of SANs formed from solution deposition methods, no unit cell structure of the SAN was observed in AFM images of samples prepared in a similar manner. Instead multi layers and aggregates of material were observed across the sample surface. Therefore, optimisation of the PTCDImelamine SAN solution deposition protocol was undertaken in order to allow reproducible formation of organised domains of the PTCDI-melamine SAN across an extended surface area. Surface chemical characterisation was undeltaken with ToF-SIMS and XPS of different Au substrate preparation methods and PTCDI-melamine SAN solution deposition protocols. In conjunction with STM images the results suggested that Korolkov's PTCDImelamine SAN solution deposition protocol and UV cleaned Au (111) substrates were the preferred sample preparation methods. SPM confrrmation of the presence of multilayers Abstract when the PTCDI-melamine SAN is deposited from solution onto Au substrates was also obtained. In order to explore the biofunctionality of the PTCDI-melamine SAN its potential bioapplication in a DNA based sensor was investigated. 12mer ssDNA oligonucleotides were selected as suitable candidate molecules. Through combination of results obtained from ToF-SIMS, XPS, AFM, STM and PF-QNM there is a suggestion that DNA hybridisation efficiency is increased when the ssDNA oligonucleotides are adsorbed onto PTCDI-melamine patterned Au (111) substrates, as opposed to when adsorbed onto bare Au (111) substrates. This is possibly due to the PTCDI-melamine SAN controlling the spatial distribution of the adsorbed ssDNA oligonucleotides, thereby reducing steric hindrance. The results described in the thesis provide proof-of-concept that the use of SANs can provide some improvements for surface biomolecule functionalisation strategies. However, further work is required to quantify several factors such as overall surface coverage of organised domains of the PTCDI-melamine SAN, and the potential improvements to surface bound DNA hybridisation efficiency. ii

The encapsulation of preformed metal/metal oxide nanoparticles (NPs) and single molecule magnets (SMMs) into hollow carbon nanostructures (CNs) and the mechanisms underpinning their synergetic interactions are described. The properties of the encapsulated species are functions of their size, composition and structural order. Hence, developing effective strategies to build functional NP/SMM@CN nano-materials with well-organized architectures would give momentum to the commercialisation of such hybrid nanostructures, ranging from nano-electronics to nano-sized reaction vessels. The use of supercritical carbon dioxide has allowed the insertion of guest-species into CNs, and the presence of the guest-species inside CNs has been confirmed unambiguously by transition electron microscopy (TEM), which still remains the only direct method of the verification for CN filling. The interior surfaces of CNs are found to influence the thermal stability of AuNPs, controlling their metastable nature and promoting the formation of linear arrangements. The catalytic activity of AuNPs retained inside CNs has been demonstrated, with excellent selectivity towards the oxidative conversion of hydrosilane to siloxane - one of the first examples of catalytic CNs. It is shown also that magnetism of metal oxide NPs and the unique characteristics of single molecular magnets remain fully preserved inside CNs, as• assessed using superconducting quantum interference device (SQUID) magnetometry. The confinement effects and the internal structure of eNs permit subtly modulation of the orientations of the magnetic guest-species and their functional properties. Magnetoresistance measurements on SMMs encapsulated in CNs have demonstrated that the electronic properties of CNs are affected by the SMMs. This is the first indication of synergistic effects within this family of hybrid nanostructures, showing promise for future applications in nana-structured electronic and spintronic devices.

This project focused on functionalising the surface of silica-magnetite nanoparticles with either acetylated diglycine or terpyridine to produce materials which could bind nickel and be used in the immobilisation/purification of histidine-tagged recombinant protein (specifically protein disulphide isomerase). The approach adopted was to 'build the ligands' on the nanoparticle surfaces and involved looking at all aspects of material synthesis, characterisation and application. Three chemical approaches were adopted for material synthesis including 'click' chemistry, carbodiimide mediated coupling of amine and carboxyl groups and the direct interaction of aldehyde with amine-functionalised nanoparticle surfaces.

This work describes the production and testing of nano-scale supramolecular interconnects or nanowires. That is, wire-like strands buih from individual molecules with a diameter in the range of 2 - 50nm. The nanowires used in this work are made up of semiconductor materials templated to a DNA backbone. Experiments have been designed to create contiguous, conductive nanowires by bonding Polypyrrole and Cadmium Sulphide to the negatively charged backbone of DNA molecules; the use of DNA is based on its one dimensional shape, conformational flexibility and its ability to create ionic bonds. Atomic Force Microscopy (ATM) is used to analyse the physical characteristics of nanowires and allows comparison with bare DNA.

Under excitation by visible light, alkylated-silicon quantum dots emit an orange- coloured luminescence, peaking at around 650 nm. Following continuous illumination, a decay of the luminescence over a time-scale of 5-10 minutes was monitored concur- rently with a photo current generated by ejection of electrons from the dots. The photoluminescence and current both decayed to non-zero, steady-state values during irradiation by visible laser light at incident intensities in the range 0.25-0.3 ± 0.01 kW /cm2; on cessation, the non-conducting photoluminescent state was substantially regained. These observations are consistent with a model in which the decay is as- cribed to autoionization of the alkylated-silicon quantum dots with a mean lifetime {Ta), depending on particle size, and recovery of luminescence to electron-hole re- combination characterized by a mean lifetime {Teh). Values of {Ta) = 1.08 ± 0.03 sand {Teh) = 770 ± 300 s were extracted from nonlinear least squares fitting to the time dependence of the photoluminescence intensity. The temporal behaviour of the transient photocurrent was found to be quantitatively consistent with a one- dimensional model of diffusion of charge carriers between quantum dots. Integration of the time-dependence of the photo current response coupled with an estimate of the volume irradiated by the laser light suggests ionization of one electron per quantum dot during photon irradiation. Measurements of the time-resolved decay of orange-band emission over a time scale of tens of microseconds and of the dependence on applied intensity of luminescence from the quantum dots were performed using pulsed laser sources. The dependence of luminescence on time was found to be strongly non-exponential and was optimally ac- counted for by a probability density function which describes a continuous distribution of two decay times: the temporal behaviour is characteristic of a pair of elementary steps connected with light emission within a distribution of local environments, or a single rate process supported by two environments. Non-linear least-squares fits to the time dependent luminescence formulated on this basis with a Gaussian, Lorentzian or log-normal distribution of rates returned most probable lifetimes T1 = 21 ± 1 μS and T2 = 3.7 ± 0.8 μS. The widths of the distributions vary between σ1 = 0.01-D.03μs-1 and az = 0.14-1.1 μs-1 associated with 1/T1 and 1/T2 respectively. The intensity of luminescence displays a linear power dependence on the intensity of the applied field, from which an exponent n = 0.94±0.02 commensurate with single-photon absorption was derived.

Nanowires are one of the basic building blocks of the bottom-up approach, for the future, in assembling nanoscale devices, engendering a continuously growing interest in the fabrication of nanowire systems with desirable properties. The present study focuses on the fabrication and characterisation of some typical nanowire systems based on anodic aluminium oxide (AAO) templates with a view toward potential applications that might emerge from the unique properties of nanowires.

Within the context of the worldwide effort in the research and development in information technologies, an investigation has been conducted mainly on the electrodeposited Coi-xPtx embedded in anodic aluminium oxide (AAO) templates by an alternating current technique. To further an understanding of the structural, magnetic, optical and magneto-optical properties of Coi-xPtx (14 nm in diameter) nanowire arrays, the chemical composition, electrodeposition time and annealing temperature dependent characteristics have been studied.

A methodology utilising the distance dependence of the rotating frame Overhauser effect (ROE) has been developed to investigate the existence of nano-structured domains in ionic liquids. A partition coefficient termed the domain preference integral ratio (DPIR) has been created to offer a simple perspective by which the preferential solubility of probe molecules in ionic liquids can be assessed. A model system, consisting of the first five oligomers of methyl methacrylate (MMA) has been designed to investigate the source of an 'ionic liquid effect' observed in the free radical polymerisation (FRP) of MMA conducted in ionic liquids. Investigation by rotating frame Overhauser effect spectroscopy (ROESY) and calculation of the DPIR has been used to probe the solvation environment of the model system. Furthermore, calculation of the DPIR for the reversible addition fragmentation chain transfer (RAFT) control agent cyanobenzoyl dithiobenzoate (CB DB) has led to a series of predictions of the outcome of the RAFT controlled FRP of MMA in ionic liquids. The reaction kinetics of the RAFT controlled reactions have been monitored to investigate the success of the methodology to predict the outcome of a reaction based upon the observed solvation environment of one of the reactant molecules.