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The major aim of this project was development of novel covalently modified glassy carbon electrodes for application in NADH-dependent biosensors using combinatorial and high-throughput methods. Studies on transition metal complexes containing redox active 1,1-phenanthroline-5,6-dione (phendione) ligand(s) showed they are effective electrocatalysts for oxidation of NADH. In order to covalently tether the metal complexes at the GC surface, the design of GC electrodes modified with novel metal complexes bearing phendione ligand(s) was proposed based on sequential electrochemical and solid-phase synthesis methods. Initial work involved optimisation of the process for modification of individual GC electrodes. Firstly, following earlier work, the GC electrodes were electrochemically functionalised by primary amines or a diazonium salt bearing Boc-protected amine groups, which allowed introduction of chelating ligands at the GC surface under solid-phase coupling conditions. The final step involved coordination of the bidentate ligand at the GC surface to the metal centre and formation of novel metal complexes under solid-phase coupling conditions. The successfully modified individual electrodes were applied in the design of a library of GC electrodes modified with different linkers, ligands and metal complexes and prepared in a combinatorial and parallel way. The library was electrochemically screened in a high-throughput way using a multichannel potentiostat, which allowed instant comparison of electrochemical and electrocatalytic properties between different members of the library. The experimental data extracted from HTP screening of the library were used for evaluation of a) the surface coverage obtained for different library members; b) the catalytic activity towards NADH oxidation and c) the kinetics parameters kcat and KM for the electrocatalytic oxidation of NADH for all members of the library.

In this thesis aluminium alloys containing small additions of both tin (~ 0.1 wt %) and gallium (~ 0.05 wt %) dissolve anodically at high rates in brine media; at room temperature, current densities > 0.2 A cm-2 can be obtained at potentials close to the open circuit potential, ~ -1.5 V vs SCE. Alloys without both tin and gallium do not dissolve at such a negative potential. The tin exists in the alloys as a second phase, typically as ~ 1 μm inclusions throughout the aluminium structure. Anodic dissolution leads to rounded pits around the tin inclusions. The pits are different in structure from the crystallographic pits observed with Al and other alloys. Clearly, the AlMgSnGa alloys dissolve by a different mechanism. Although the distribution of the gallium in the alloy could not be established, it is essential to the formation of these pits and maintaining dissolution. In addition to the composition, mechanical working and heat treatment influence both the stability of the alloys to open circuit corrosion and the overpotential for high rate dissolution, factors critical to battery performance. The correlation between performance and alloy microstructure has been investigated. Imaging with a high speed camera with a resolution of 10 – 20 μm was used to observe the dissolution of AlMgSnGa alloys. Using microelectrodes with only a few Sn inclusions in their surface, allows confirmation that hydrogen evolution occurs only from the Sn inclusions and also showed that the evolution of H2 is not continuous. Therate of H2 evolution correlates with shifts in potential between - 1.5 V and much less negative potentials. The performance of a laboratory Al-air battery with 2 M NaCl electrolyte was limited by both the performance of the O2 cathode and the extent of dissolution of the alloy. Using a cell with a low electrolyte volume/surface area ratio, dissolution of the anode stopped after the passage of 1000 C cm-2 due to a high impedance, thick film of crystals clinging to the surface. Removal of this film allowed the dissolution to recommence. The charge limitation depends on cell design but a high charge density would be difficult to achieve with a low volume battery.

This work presents the development of electrowetting on dielectric and liquid dielectrophoresis as a platform for chemistry, biochemistry and biophysics. These techniques, typically performed on a single planar surface offer flexibility for interfacing with liquid handling instruments and performing biological experimentation with easy access for visualisation. Technology for manipulating and mixing small volumes of liquid in microfluidic devices is also crucially important in chemical and biological protocols and Lab on a Chip devices and systems. The electrodynamic techniques developed here have rapid droplet translation speeds and bring small droplets into contact where inertial dynamics achieve rapid mixing upon coalescence. In this work materials and fabrication processes for both electrowetting on dielectric and liquid dielectrophoresis technology have been developed and refined. The frequency, voltage and contact angle dependent behaviour of both techniques have been measured using two parallel coplanar electrodes. The frequency dependencies of electrowetting and dielectrophoretic liquid actuation indicate that these effects are high and low-frequency limits, respectively, of a complex set of forces. An electrowetting based particle mixer was developed using a custom made electrode array and the effect of varying voltage and frequency on droplet mixing was examined, with the highest efficiency mixing being achieved at 1 kHz and 110 V in about 0.55 seconds. A composite electrodynamic technique was used to develop a reliable method for the formation of artificial lipid bilayers within microfluidic platforms for measuring basic biophysical aspects of cell membranes, for biosensing and drug discovery applications. Formation of artificial bilayer lipid membranes (BLMs) was demonstrated at the interface of aqueous droplets submerged in an organic solvent-lipid phase using the liquid dielectrophoresis methods developed in this project to control the droplet movement and bring multiple droplets into contact without coalescence. This technique provides a flexible, reconfigurable method for forming, disassembling and reforming BLMs within a microsystem under simple electronic control. BLM formation was shown to be extremely reliable and the BLMs formed were stable (with lifetimes of up to 20 hours) and therefore were suitable for electrophysiological analysis. This system was used to assess whether nanoparticle-membrane contact leads to perturbation of the membrane structure. The conductance of artificial membranes was monitored following exposure to nanoparticles using this droplet BLM system. It was demonstrated that the presence of nanoparticles with diameters between 50 and 500 nm can damage proteinfree membranes at particle concentrations in the femtomolar range. The effects of particle size and surface chemistry were also investigated. It was shown that a large number of nanoparticles can translocate across a membrane, even when the surface coverage is relatively low, indicating that nanoparticles can exhibit significant cytotoxic effects

The work in this thesis addresses the synthesis and characterization of porous carbon substrates, and their electrochemical and fuel cell evaluation. The approach involves using porous carbon materials of different pore characteristics as electrocatalyst materials for use as cathode catalyst substrates in direct methanol fuel cells (DMFC). In this work, a porous carbon, known as carbonaceous Celatom or C-Celatom, was prepared by template synthesis using a widely abundant, inexpensive macroporous silica structure diatomaceous earth (Celatom FW-80). Ordered mesoporous carbon CMK-3 was also produced by template synthesis of mesoporous silica SBA-15. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to confirm the synthesis of the desired carbon structures. Three different platinum deposition techniques were investigated for electrocatalyst synthesis, an incipient wetness technique, as ethylene glycol reduction technique, and an alkoxide reduction technique. Transmission electron microscopy (TEM) and SEM analysis of the catalysts formed using the incipient wetness and ethylene glycol techniques showed that the synthesized catalysts were not suitable for fuel cell use. Optimization of the alkoxide reduction technique resulted in a deposition technique that resulted in a well-dispersed catalyst with small, uniform particle sizes (2.1-3.1 nm). The synthesized electrocatalysts were evaluated electrochemically and found to have high electrochemically active surface areas (ESA) of 33.38 m2 g-1 for Pt/Vulcan XC-72, 22.45 m2 g-1 for Pt/CMK-3 and 20.51 m2 g-1 for Pt/C-Celatom. The oxygen reduction (ORR) activity was evaluated by linear sweep voltammetry(LSV). The Pt/C-Celatom exhibited the greatest activity towards the oxygen reduction reaction, and the greatest number of active sites for the ORR. Assessment of the material by electrochemical impedance spectroscopy (EIS) also showed that an MEA with C-Celatom as the cathode catalyst has the lowest combines charge transfer and mass transport resistance. Single cell DMFC testing was carried out with each of the experimental substrates. The synthesized catalysts demonstrated high performance over a range of temperatures and feed molarity concentrations. The C-Celatom MEA exhibited the greatest power output of the synthesized catalysts for low molarity operation, with peak power densities of 25.8 and 32.6 mW cm-2 with 0.5M and 1M feed respectively.

With the growing importance of organic photovoltaics (OPVs) as an attractive, low cost and sustainable energy source the field has been investigated intensively, showing high potential for commercialisation. To further improve device performance, different routes of development have been explored targeting interfaces that play a crucial role in device performance including the donor (D)/acceptor (A) and electrode/photoactive layer interfaces, as well as incorporation of new materials. Vertical co-deposition of water-soluble small molecule copper(II) phthalocyaninetetrasulfonic acid tetrasodium salt (TSCuPc) and polymeric sodium poly[2-(3- thienyl)ethoxy-4-butylsulfonate] (PTEBS) with polystyrene (PS) nanospheres to template, followed by solvent vapour sphere removal, is shown as an excellent method to generate three-dimensionally ordered macroporous large area thin films of sub-100 nm pore size. After a subsequent infiltration by the electron acceptor phenyl-C61-butyric acid methyl ester (PCBM), three-dimensionally (3D) interdigitated D-A composite structures are generated which are further implemented in complete OPV devices. PTEBS based 3D nanostructured D-A composite devices reached a comparable performance to planar reference devices but did not show the expected photocurrent improvement. This is most likely due to the complexity of this multistep fabrication method and the large probability if impurities in the films. However, it demonstrates a new approach towards nanoengineered 3D interdigitated organic D-A composite OPV devices. For this templating technique monodisperse sub-100 nm PS nanospheres were synthesised by radical initiated surfactant-free emulsion polymerisation controlling different parameters with particular focus on styrene-4-sulfonic acid sodium salt (NaSS) co-monomer concentration. Furthermore, planar heterojunction OPV devices from TSCuPc and PTEBS were studied in detail and optimised for further understanding of the 3D D-A composite devices. A substantial increase in device performance and operational stability in solution processed inverted bulk heterojunction (BHJ) OPVs is demonstrated by introducing a zinc oxide (ZnO) or titanium oxide (TiOx) interlayer between the electron collecting bottom electrode and the photoactive blend of poly(3-hexylthiophene) (P3HT) and PCBM. The introduction of transition metal oxide (TMO) interlayers resulted in a remarkable increase in power conversion efficiency (PCE) with a maximum value of 4.91 %. The structure and morphology of the dense, planar ZnO layers was controlled either by electrodeposition or spray pyrolysis techniques. Organic/inorganic hybrid OPVs combine the advantages of both types of semiconductors and offer an alternative to replace fullerene based electron acceptor materials. The small molecule organic semiconductor, boron subphthalocyanine chloride (SubPc), is a promising donor material for fabrication of inverted planar hybrid solar devices using TiOx as the electron acceptor. The TiOx/SubPc cells demonstrate performance characteristics comparable to the best-reported polymer/TiOx hybrid cells. A relatively high photocurrent and a maximum external quantum efficiency (EQE) of 20 % lead to a PCE of 0.4 % under AM1.5 solar illumination.

The AsF6- anion, in the crystalline polymer electrolyte PEO6:LiAsF6, was replaced with the larger N(SO2CF3)2- anion. This produced an increase in the room temperature ionic conductivity of 1.5 orders of magnitude. It is believed that the enhancement is the result of the disruption of the electrostatic field around the lithium ions. The presence of the large and asymmetrical N(SO2CF3)2- ion creates a greater number of defects and thus enhances conductivity. These results demonstrate for the first time the enhancement lithium ion conductivity in a crystalline polymer electrolyte by isovalent doping. XF6- anions, in the crystalline polymer electrolyte system PEO6:LiXF6, were replaced by another anion of similar size and shape. A continuous solid solution was obtained for PEO6:(LiAsF6)1-x(LiSbF6)x. These results represent the first continuous solid solution demonstrated in the field of crystalline polymer electrolytes. They also show for the first time an enhancement of conductivity caused only by the size of the dopant anion. The enhancement is believed to originate from changes in the length of the crystal axis and changes in the potential landscape around the lithium ions. The structures of the glyme complexes monoglyme:LiAsF6, hexaglyme:LiAsF6, octaglyme:LiAsF6, undecaglyme:LiAsF6 and dodecaglyme:LiAsF6 have been solved. There structures are discussed and compared to that of PEO6:LiAsF6. The properties of these complexes together with those of diglyme:LiAsF6, triglyme:LiAsF6 and tetraglyme:LiAsF6 were investigated. Triglyme:LiAsF6 has been shown to demonstrate high ionic conductivity of 10-5.5 Scm-1 at 30oC as well as a high transport number of 0.8. These complexes demonstrate the control that crystal structure has over ionic conductivity. These complexes are neither ceramic nor polymeric. A number of the complexes show plastic crystal like solid-solid phase transitions.

The results presented in this thesis demonstrate the first synthesis of several nanostructured transition metal oxides and lithium containing transition metal oxides. Their uses in lithium-ion batteries and/or as magnetic materials have been investigated. The first example of two and three dimensional mesoporous Fe₂O₃ has been prepared by using the soft templating (surfactant) method. The materials have amorphous walls and exhibit superparamagnetic behaviour. By using a hard template route, a mesoporous α-Fe₂O₃ with highly crystalline walls has been synthesized. Its unique magnetic behaviour, distinct from bulk α-Fe₂O₃, nanoparticulate α-Fe₂O₃, and mesoporous Fe₂O₃ with disordered walls, has been demonstrated. The hard template method was also used to prepare nanowire and mesoporous Co₃O₄, β-MnO₂ and MnO₃ with crystalline walls. Their electrochemical properties as electrodes in Li-ion batteries have been investigated. Mesoporous β-MnO₂ can accommodate 0.9 Li/Mn in stark contrast to bulk β-MnO₂ which cannot accommodate Li. To prepare mesoporous materials which cannot be obtained directly by the hard template method, a post-templating route has been developed. Mesoporous Fe₃O₄, γ-Fe₂O₃, and Mn3O4 with ordered mesostructures and highly crystalline walls have been obtained by post-synthesis reduction/oxidation treatments. All the materials show unique magnetic properties compared with nanoparticulate and bulk materials. Also, the first example of lithium containing mesoporous material, LT-LiCoO₂, was synthesized by first preparing mesoporous Co₃O₄, then reacting this with LiOH to form LT-LiCoO₂, with retention of the ordered nanostructure. The nanostructured LT-LiCoO₂ compounds demonstrate superior performance compared with normal or nanoparticulate LT-LiCoO₂, when used as intercalation electrodes in lithium batteries. Finally, monodispersed Mn₃O₄ nanoparticles (diameter ~ 8 nm) with a core-shell structure (a highly crystalline Mn₃O₄ core encased in a thin MnO₂ shell) have been prepared for the first time. Ordered three-dimensional arrays form by spontaneous self-assembly. Magnetic measurements demonstrated that the self-assembled three-dimensional arrays exhibit spin-glass behaviour, rather than the anticipated superparamagnetic behaviour for isolated nanoparticles. Such behaviour is interpreted as arising from strong interactions between the core (crystallized Mn₃O₄) and shell (MnO₂).

This thesis is concerned with the synthesis and study of novel anion templated rotaxanes and catenanes for electrochemical anion sensing, as well as interlocked structures that possess different anion binding properties, higher-order topologies and the ability to undergo molecular motion. Chapter One provides an introduction to anion recognition and the preparation of interlocked structures. A short summary of fundamental aspects of supramolecular chemistry is followed by detailed surveys of current approaches to anion binding and sensing, as well as the templated synthesis of rotaxanes and catenanes. Chapter Two describes the preparation of rotaxanes and catenanes appended with ferrocene to allow for electrochemical anion sensing. The anion recognition properties of a [2]rotaxane and a [2]catenane, as investigated by ¹H NMR spectroscopy and electrochemical methods, are presented. The utilization of a ferrocene-appended macrocycle in the construction of surface confined anion templated rotaxanes and catenanes is also discussed. Chapter Three reports the work carried out to achieve electrochemical anion sensing by the incorporation of redox-active groups into the integral structures of interlocked structures. The syntheses of a bis-stoppered 1, 2, 3, 4, 5-pentaphenylferrocene [2]rotaxane and a ferrocene containing [3]rotaxane are presented, along with their subsequent anion recognition studies. In addition, attempts to incorporate ferrocene into the macrocyclic components of rotaxanes and catenanes are outlined. Chapter Four details further investigations into the use of interlocked structures to achieve anion recognition. Doubly-charged [2]catenanes able to bind anions in aqueous solvent media, as well as the incorporation of alternative anion binding motifs into interlocked architectures are reported. The exploitation of anion templated synthesis to allow for the construction of higher order structures (including [3]catenanes, a “handcuff” catenane and a Janus [2]rotaxane), as well as a [2]catenane system with anion controlled molecular motion is also described. Chapter Five presents the experimental procedures and characterization data relating to the compounds prepared in Chapters Two, Three and Four. Chapter Six summarizes the main conclusions of the work contained within this thesis. Supplementary experimental information relating to titration protocols, investigations into self-assembled monolayers (SAMs) and crystallographic data are provided in Appendices I, II and III.

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