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This thesis concerns the discovery of superconductivity in the intercalated graphite compounds C6Yb and C6Ca. A novel technique for synthesis of these intercalates has been developed, and is presented in detail. These two materials are shown to superconduct at 6.5K and 11.5K respectively. The superconductivity is demonstrated by measurements of the magnetisation and resistivity. Initial measurements of the superconducting transition of these materials as a function of pressure shows an increase in the transition with increasing pressure.

This thesis deals with the nature of fundamental intermolecular interactions and the ways in which they can be exploited using supramolecular chemistry. Three separate studies have been undertaken in order to explore and quantify different types of electrostatic interactions. Chapter 2 describes an investigation into the nature of hydrogen bonding interactions between charged species and well-defined neutral hosts, in order to quantify their hydrogen bonding strength on an already established scale. The importance of metal-ligand interactions in self-assembly is documented in Chapter 3, where the synthesis of functional supramolecules is described and their self-assembly in the presence of a bidentate ligand is investigated. Finally, Chapter 4 describes the use of calixarene-porphyrin conjugates in gas-sensing devices, showing how a handle on the design and synthesis of supramolecules and an understanding of their basic interactions can provide a useful application. The detailed background literature relating to the project will be described as an introduction to each chapter; this chapter provides a general introduction to the field of supramolecular chemistry and an overview of key advances that have been made since its inception.

This thesis begins with the investigation of size- and density-effects of AgNP arrays in voltammetry, including the study of size-dependent adsorption behavior by observing thallium underpotential deposition on AgNPs, and surface coverage eects of AgNP modified electrodes in voltammetry showing the transition from convergent to linear diffusion. The main focus of this thesis is next presented: the electroanalysis of nanoparticles (NPs) studied via their impacts with an electrode via both indirect (i:e: electrocatalytic) and direct electrochemical measurements. The study first realises the direct detection and sizing of silver NPs (AgNPs) using anodic particle coulometry (APC). This theme is then extended to gold and nickel NPs, aggregation studies and the measurement of sticking coecients. Furthermore, the determination of nanoparticle concentration is realised by measurement of the flux to electrodes. In contrast to APC, electrode-particle impacts using surface tagged NPs provide a non-destructive way of sizing the NPs from the charge associated with one monolayer of "tag". In addition to tagged NPs, underpotential deposition and bulk deposition of metal onto single AgNPs are also observed as part of the studies of indirect electrochemical measurement. Finally the charge transfer kinetics of the oxidation of silver and nickel nanoparticles is studied.

Electrochemistry finds widespread applications in the field of chemical analysis, so-called electroanalysis, as well as in electrosynthesis. The results obtained can be highly dependent on the chemical nature of the electrode used, and chemically modified electrodes are often employed to fine tune the electrochemistry to suit particular applications. This thesis is concerned with the investigation of the use of carbon materials, both as electrode substrates and electrode modifiers, primarily for electrochemical analysis. The work has been carried out using a range of electrochemical voltammetric techniques, as well as impedance measurements. A number of physical methods, including electron microscopy and X-ray photoelectron spectroscopy, have also been used to determine the physical and chemical structures of the materials employed. The use of boron-doped diamond electrode (BDDE) for the electrochemical detection of H₂O₂ was explored. Although BDDE shows no useful electrochemical response to H₂O₂, a good electrochemical signal can be obtained if the electrode is modified with silver nanoparticles or haemoglobin. The best results are obtained using electrode interfaces fabricated by binding haemoglobin in an active form to silver nanoparticles prepared by electrodeposition on the BDDE in the presence of the surfactant CH₃(CH₂)₁₅Br, permitting state of the art performance with a limit of detection (LOD) < 0.5μM. The presence of haemoglobin at the BDDE surface is also capable of catalysing the electrochemical reduction from Ag⁺(aq) to silver particles. However it reduces their adhesion to the electrode surface, hence they are lost to solution. This observation was used to demonstrate a viable process for the electrosynthesis of Ag nanoparticles, producing particles of about 10 nm diameter at a yield of approximately 50%. The effects of modifying a glassy carbon electrode with various forms of nanocarbon material for the electrochemical detection of phenolic compounds including hydroquinone (HQ) and dihydroxybenzene (DHB) were studied. The nanocarbons considered included carbon black, graphene nanoplatelets and nanodiamond, for which the former two materials were found to show a large increase in the detection sensitivity. It was shown that the simultaneous detection of HQ and DHB was possible using these electrodes, and in 'real' samples such as river water and green tea. Additional modification of the electrodes with tyrosine also permitted detection of phenol and p-cresol. The nanodiamond and carbon black modified electrodes were also employed for the electrochemical detection of Bisphenol A (BPA), which can be severely hampered by electropolymerisation of the oxidation products of BPA, producing rapid electrode fouling. However because of the inert nature of diamond surfaces, it is shown that this fouling process can be minimised by modifying the glassy carbon electrode with nanodiamond. Alternatively, it was also observed that for the carbon black modified electrode, a strong electrochemical response could be seen associated with the quinone forms produced by BPA oxidation. The associated electrochemical signal is also found to be relatively insensitive to electrode fouling, opening up an alternative strategy for the detection of BPA. Finally the use of a carbon black modified glassy carbon electrode for the detection of dopamine in the presence of the interfering compounds, ascorbic and uric acids, was studied. The carbon black modifier is shown to increase detection sensitivity, and help separate the electrochemical signals of the differing redox active species present in the solution.

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Fuels such as hydrogen, produced from renewable resources and efficiently utilized in environment friendly fuel cells are crucial to long term energy security. However, the lack of cost-effective catalysts, with a performance similar to that of platinum, is a major obstacle to the development of the fuel cell technology. This work researched cheap and environmental friendly oxygen reduction catalysts, based on carbon, which can replace platinum for oxygen reduction reaction (ORR) in the cathode of alkaline and microbial fuel cells. Nitrogen doped mesoporous carbon was prepared by pyrolyzing 1,2-diaminobenzene in a template of highly ordered mesoporous silica (KIT-6) at 700, 800 and 900 oC. Manganese oxides are active catalysts for ORR and as they are an earth abundant metal with widespread availability, this offsets a key drawback of the platinum group metals (PGM). A simple chemical deposition method (using KMnO4) and physical deposition followed by heat treatment (using Mn(NO3)2) was used to prepare amorphous and crystalline manganese oxides which were separately deposited on ordered mesoporous nitrogen doped carbon (OMNC) and on ordered mesoporous carbon (OMC) without nitrogen doping respectively. The catalysts were characterized by Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Raman Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and nitrogen adsorption-desorption. Cyclic voltammetry and linear sweep voltammetry (LSV) with a rotating-ring disk electrode (RRDE) were used for electrochemical characterisation of the iv oxygen reduction reaction (ORR). They were also tested as cathode catalysts in a microbial fuel cell. The best catalysts in alkaline media (0.1 M KOH) were amorphous manganese oxide on OMNC and OMC. They had onset potentials of 1.04 V and 1.05 V (RHE); half-wave potentials of 0.83 V and 0.82 V (RHE) respectively. This behaviour may be because the amorphous oxide maintained the ordered pore structure of the catalysts by depositing a thin coating of nanoparticle catalysts within them, thus causing a fast three phase reaction and excellent catalyst utilization. In the microbial fuel cell, the best catalysts were the amorphous MnO2 on OMC and on nitrogen doped carbon pyrolyzed at 900oC with equal power densities of.

The study of radiation chemistry is very important because of the wide range of applications. Many of the processes in radiation chemistry evolve randomly and can be modeled using the theory of stochastic process. The main aim of this thesis is to study correlation effects in model systems of the type found in radiation chemistry, i.e. clusters of reactive particles. Studies of this type involve a substantial amount of computer simulation. The first work described in the thesis shows how the Message Passing Interface can be incorporated in the algorithms used to simulate radiation chemical kinetics and how that can improve the performance of the programs. The reaction probability for two diffusing particles is well known, and current theories are based on this, making the approximation that pair distances evolve independently. This work analyses some correlation effects that appear in a system of three particles, with some new results, notably in the distribution of the joint distribution of the distances and the underlying 3-body backward diffusion equation, but it has not yet been possible to use these results to introduce corrections in the working simulations. The competition between scavenging and recombination is investigated in detail in chapters 4-6. A correction to the Smoluchowski theory for a fully-diffusion controlled reaction is proposed, and it is shown how the Independent Reaction Times method can be used to simulate this competition. The approximation is justified both by comparison to simulation results and theoretically, and is shown to apply to all the ordered scavenging reactions in a multi-particle system. Finally, the problem of modeling a reversible reaction is briefly investigated in chapter 7. The main result of this chapter is a generalization of previous work on the distance between a pair conditional on its future reaction time, generalized to a radiation boundary condition.