Molecular simulations have become a mainstream tool of the physical sciences. In spite of their success in allowing us to understand the behaviour of matter at a molecular scale, current and foreseeable computational power limits the system sizes and time scales of ob- servation. Many common engineering scenarios, e.g., self-assembly of aqueous surfactant solutions, require access to large systems and long time scales. A coarse-graining method- ology, in which atoms and molecules are grouped into beads can be used to capture this behaviour using molecular simulation. However, the development of coarse-grained force fields for use in molecular simulation to study structural, thermodynamic and dynamical properties still remains a challenge. This challenge is the focus of the work presented in this thesis. Coarse-grained force fields obtained in this work were used in molecular simulations for a broad range of systems including: fluid phases of small molecules such as carbon dioxide, linear chains of alkanes, siloxanes and alcohols, to more complex aqueous systems of non- ionic surfactants, electrolytes, and ionic surfactants. The coarse-grained models were developed using a molecular-based equation of state of the Statistical Associating Fluid Theory (SAFT) family, based on the Mie (generalised Lennard-Jones) inter-molecular potential for the interactions between beads. This allows the structural, dynamical, and interfacial properties to be studied directly in molecular simulation. A transferable coarse-grained model for linear alkanes was developed. The carbon chains were used to form the backbone of a variety of organic molecules. Coarse-grained potentials for charged species were also obtained using an electrolyte version of the theory (SAFT-VRE) for use in molecular simulations. The coarse-grained models developed for the linear alkanes and aqueous electrolytes were subsequently used to establish a coarse- grained force field for the aqueous mixture of an important ionic surfactant: sodium dodecyl sulphate. The phase behaviour of the aqueous solutions of sodium dodecyl sulph- ate was studied with the coarse-grained models by molecular dynamic simulations, with emphasis on the structural properties of the different phases. Graphic processing units were also employed to perform large-scale simulations of the coarse-grained SAFT-γ Mie models of aqueous solutions of a non-ionic surfactant: tetraethylene glycol monodecyl ether. Despite the relative simplicity of the coarse-grained force fields developed using the SAFT-γ Mie equation of state, the models were robust and transferable. Properties that have not been considered in the original parameterisation procedure can be predicted, and the results are comparable with the more sophisticated and computationally demanding atomistic and united atom models. Therefore, the methodology developed in this work can be employed in a wide range of industrial and academic applications to help bridge the gap between the microscopic and macroscopic scales.

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Oxygen is remarkable in that it has a triplet ground state, a 3Σg state, with its first two excited states being of singlet multiplicity (1Δg and 1Σg+, lying 94 kJ mol-1 and 158 kJ mol-1 above the ground state, respectively). Relaxation of the singlet state to the ground state is consequently spin forbidden, resulting in a long lifetime for singlet oxygen: Singlet oxygen is a highly reactive species and is responsible for oxidative damage in a number of systems. In this study, singlet oxygen quantum yields, ΦΔ, have been measured at varying temperatures and pressures, as a function of oxygen concentration, in supercritical fluid carbon dioxide.

The work presented in this thesis reports the preparation and characterisation of novel solid lipid microparticle (SLM) and solid lipid nanoparticle (SLN) systems for applications in delivery of laundry actives and transport of electroactive substances into lipid membranes. The SLM and SLN systems studied are: silicone-loaded SLM, dye-loaded SLM, dual-active SLM (both silicone and dye) and ferrocene-loaded SLN (Fc-SLN). Silicones are used as fabric softeners in laundry applications and dyes are used to enhance the hue of fabrics. The incorporation of two actives into one, dual-active SLM, is a concept that could enable compact formulation and optimized formulation manufacture. The ferrocene-loaded SLN system represent the group of electroactive nanoparticles that could potentially find applications in biosensors, targeted delivery and other biomedical applications. The SLM and SLN systems were prepared using lauric acid as the lipid matrix. Silicone-loaded SLM systems were prepared using solvent-assisted methods with either ethanol or n-hexane as the solvent. They were stabilized with a combination of a primary alcohol ethoxylate (C14-15) (neodol 45-7) and polysorbate 80 (tween 80) as surfactant/co-surfactant). The silicones used were: polydimethylsiloxane (PDMS)(10,000 cST and 100,000 cSt), terminal amino-functionalised silicone (TAS) and a tertiary amino-functionalised silicone (PK10). The dye-loaded SLM systems, incorporating Coomassie Brilliant Blue R (CBB or BB) and ethyl violet (EV, Basic Violet 4) as hueing dyes were prepared using the double emulsion method, also descriptively known as the water-in-oil-in-water (w/o/w) emulsion method. The inner emulsion, w/o was stabilized using a low HLB surfactant, Brij 80 and the outer emulsion o/w was stabilized using a high HLB surfactant, tween 80. For the dual-active SLM system, PK10 silicone was added to the lipid phase before emulsification. The Fc-SLN system was prepared using the solvent emulsification/evaporation method. The surfactants used were poloxamer 188 and tween 80. The lipid membrane systems used were: solid-supported self-assembled monolayer (SAM) and tethered bilayer lipid membrane. The SAM was prepared by chemisorption of a thiolipid, 1,2-dipalmitoyl-sn-glycero-phosphothioethanol (DPPTE) onto a gold surface. Self-assembled monolayers were used as a lower leaflet or tether for the BLM system; an upper leaflet of 1-palmitoyl-2-oloeyl-sn-glycero-3-phosphocholine (POPC) was added by vesicle fusion. The characterisation and penetration of Fc-SLN into lipid membranes was studied using electrochemical methods such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and Resonance Enhanced Surface Impedance (RESI). The SLM and SLN systems where characterised using laser diffraction and dynamic light scattering (DLS) for particle size analysis, optical microscopy and electron microscopy for morphology and particle size, small angle X-Ray Scattering (SAXS) and differential scanning calorimetry (DSC) for crystallinity and structural arrangement and chemical analysis using FTIR, solid state NMR and TGA.

The coordination behaviour of the pseudohalide ions (NCO ̄ NCS ̄ NCSe ̄ NCTe ̄) has been studied. A number of N- and S-bonded thiocyanate complexes of rhodium(I), of the type Rh(PPh3)2(L)CNS (L = ligand), have been prepared. The mode of linkage of the thiocyanate group has been established by means of infrared spectral measurements. The preparation of Rh(PPh3)2(piperidine)NCS clearly demonstrates that a strongly π-accepting ligand such as CO is not a prerequisite for a N-thiocyanato complex of the type Rh(PPh3)2(L)NCS.

Ceria is well known for its unique properties in fast oxygen mobility and formation of oxygen vacancies which makes ceria an excellent catalyst support for metal nanoparticles. Promotional effect of ceria has been well established in a number of reactions including three-way catalyst and CO oxidation. These unique properties of ceria are dependent on the surface facets it exposes, where they can be enhanced by the exposure of high energy surfaces such as (100) and (110). The work presented in this thesis involves controlling the surface exposed by the ceria support by making them into cube and rod morphology, which predominantly expose the (100) and (110) surface, respectively. Hence, the effect of these surfaces on the ceria support can be investigated. The ceria morphologies were deposited with Pd nanoparticles and their catalytic properties were tested on methane combustion and gas-phase formic acid decomposition reactions. In both of the catalyst test reactions, the Pd deposited on the ceria cubes support had shown superior catalytic properties compared to the Pd deposited on the ceria rods support, indicated by the former's higher activity, TOF and resistance to poisoning. Based on the characterisation techniques performed in this study such as TPR, ambient pressure XPS, STEM-EELS and pulse isotopic oxygen exchange, the enhanced catalytic properties of Pd/ceria cubes were attributed to the high energy ceria (100) surface which led to more favourable formation of oxygen vacancies and faster oxygen mobility.

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This thesis describes the development and application of a new in situ infrared (IR) approach to studying electrocatalysis at supported nanoparticle catalysts that are used in proton exchange membrane (PEM) fuel cells. Such fuel cells running on small organic molecules are an attractive technology for use in transport applications and portable electronic devices, however one major challenge facing this technology is the slow oxidation of the organic molecules at the electrode surface. Furthermore, the mechanisms by which these organic molecules are oxidised are still not clear, hampering the design of new electrode materials. In situ IR spectroscopy has been used extensively to investigate the mechanism of reactions on model catalysts, however extension of these techniques to real fuel cell catalysts is challenging and much less advanced. A new approach to in situ IR spectroscopy of supported electrocatalysts is therefore developed, inspired by the geometry of PEM fuel cell electrodes. The approach overcomes many of the limitations of previous approaches, allowing solution flow over the catalyst layer, cyclic voltammetry up to scan rates of 1 V s-1 and spectroscopic detection of surface adsorbed species with time resolution of 0.5 s. The utility of this approach is demonstrated through a study of the mechanism of two model reactions, carbon monoxide (CO) and formic acid (FA) oxidation, on a commercial fuel cell catalyst. In situ IR measurements made during CO stripping experiments on a commercial carbon-supported Pt catalyst reveal two strongly bipolar IR peaks in the CO stretching region. An empirical model for the bipolar peak shape is developed and used to extract peak parameters. Electrochemical measurement of the CO coverage then enables calibration of the IR peak intensity with coverage. This quantitative relationship enables features such as dipole-dipole coupling in the CO adlayer to be discussed. In situ IR spectra recorded during the stripping voltammogram reveal the presence of two linear CO peaks, assigned to different sites on the catalyst. The potential dependence of the two peak intensities is used to discuss the mechanism of CO oxidation on the catalyst. The in situ approach is extended to the study of FA oxidation on the commercial Pt catalyst. As well as adsorbed CO, two potential-dependent peaks are assigned to adsorbed formate - the first time formate has been observed on a nanoparticle catalyst during electrooxidation. Furthermore, one of the peaks is assigned to an IR surface selection rule-prohibited mode, providing evidence for the previously proposed size-dependence of the selection rule. The effects of concentration, pH, isotope and supporting electrolyte on the adsorbed species are examined and related to the current in order to understand different aspects of the mechanism on nanoparticle catalysts. The results are discussed in the context of previous work on macroscopic electrodes. Overall an approach to in situ IR spectroscopy of nanoparticle electrocatalysts is presented and is used to probe the mechanisms of CO and FA oxidation under conditions relevant to fuel cells.