No description available.

In this study, the adsorption of 2-butanol and furfural was investigated on Au (111), Cu (111) and Cu/Au (111) surfaces. It was hoped that by studying how these species adsorbed on these surfaces , insight would be provided into the roles of Cu and Au in the “hydrogen free” hydrogenation of furfural to furfuryl alcohol. This is a valuable process as currently furfuryl alcohol is derived from crude oil but it is possible to derive furfural from corn husk making it a greener process. The surfaces were studied under ultra-high vacuum conditions using scanning tunnelling microscopy, thermal desorption spectroscopy and high resolution electron energy loss spectroscopy. The mixed metal systems were prepared via metal vapour deposition of Cu onto a Au (111) single crystal. From the data generated it was found that on Cu, 2-butanol adsorbed primarily at the step edges and surface defects at room temperature resulting in the formation of butanone as well as small amounts of propanal and ethane. On gold there is very limited adsorption resulting in species adsorbed with a random orientation with respect to the surface. On the mixed metal system, it was discovered that the order of the butanol and copper dosing has a significant effect on the orientation of the adsorbed species as well as the surface morphology. However the TDS results suggest that the surfaces are chemically similar. When furfural was dosed on the Cu (111) surface it was found to break down into small chain hydrocarbons and CO species. The furfural formed small chain like features on the surface. On the mixed metal system, the furfural appears to adsorb on top of the copper islands causing a loss of resolution in STM measurements.

No description available.

No description available.

Prompted by growing environmental and energy concerns, increasing research is dedicated to the development of technologies capable of sustainably converting sunlight into commercially viable forms of energy such as chemical fuels. Crucial to this energy conversion is the availability of materials, photo-catalysts (PCs), capable of promoting redox chemistry following absorption of light. Since the macroscopic efficiency of PCs is governed by the atomistic details of the PCs interfaces with media and reactants, increasingly large efforts have been dedicated to the characterization and understanding of these interfaces, also by mean of first principle simulations. In this context, we present a theoretical investigation of a rapidly growing class of onedimensional nanomaterial, Imogolite nanotubes (Imo NTs), whose potential for photocatalysis has so far been overlooked. The first Chapter of the Thesis provides an overview of the current state of the art for research in PCs, and the theoretical framework needed for atomic-scale understanding and informed development of PCs. The computational underpinning of the research carried out for this Thesis, namely Density Functional Theory (DFT) and its linear-scaling (LS) implementation in the ONETEP program is presented and discussed in Chapter 2. Ahead of presentation of the results of my original research, a small literature review on Imo NTs is provided in Chapter 3. Chapter 4 illustrates the applicability of LS-DFT to Imo NTs and, by mean of detailed benchmarking, sets best practice for simulations of these systems. The potential of Imo NTs as (co-)PCs is explored in Chapter 5, where an extensive study of the structure, wall-polarization, absolute band-alignment, band-separation, and optical properties of several Imo NTs is presented and discussed. The simulations suggest possible profitable use of Imo NTs for both photo-reduction and hole-scavenging purposes. The occurrence of (near-)UV charge-transfer excitations is also observed, which may be effective for electron-hole separation and enhanced photo-catalytic performances. Finally, the effects of the NTs’ wall-polarization on the absolute alignment of electron and hole acceptor states of interacting water (H2O) molecules are quantified and discussed. Chapter 6 reports an extensive study of defects in Imo NTs. Electronic and optical characterization of the defective Imo NTs suggests energetically favourable separation of photo-generated electrons and holes via relaxation to different defect-sites, with the ensuing possibility of defect-centred photo-redox activity in defective Imo NTs. The Thesis ends with the investigation of termination effects in Imo NTs. Chapter 7 presents results on the structural, electronic and optical characterization of representative finite Imo NTs models capable of simultaneous description of the NT-ends and bulk-like NT-core. The simulations reveal the presence of longitudinal band-bending and of NT core-end bandsseparations, which in turn suggests advantageous relaxation mechanisms for photo-generated e*-h pairs along the NT axis, to the potential benefit of Imo NTs photo-catalytic reactivity.

A comprehensive account is given of the work associated with the design, development and production of a high-performance battery from the issuing of a new and demanding specification. Theoretical considerations coupled with a survey of the field led to a choice of a suitable couple. Laboratory methods for producing electrodes in quantity were worked out in order to enable the operating parameters of the cell to be optimised by a study of discharges under various conditions. Production methods for the electrodes were developed and various problems, in particular those stemming from locked up stresses in electro-deposits, were solved in the laboratory. The high performance specified could only be achieved by using perchloric acid electrolyte; important successes were achieved in reducing the fire and explosion hazard associated with this substance. Thus far the final cell (and battery design) has proved eminently satisfactory not only in meeting specified performance but in maintaining activity after more than two years of dry storage. In addition full-scale production, based on the methods evolved in the laboratory, is proceeding smoothly.

The condensation of mixtures of vapours of immiscible liquids is a process which occurs frequently in the oil and chemical process industries, particularly where such processes as steam distillation, heterogeneous azeotropic distillation and solvent drying are used. Yet the process is not understood. The discrepancies between the heat transfer coefficients reported by previous workers in this field are so large that none of the published correlations can be confidently used for design purposes. The relationships found between heat transfer coefficient and temperature driving force differ so widely that it is impossible to predict., without prior experimentation, the behaviour of condensers when operating conditions are changed. The present state of knowledge in this field is such that it is not known whether the factor controlling heat transfer rate during condensation is simply the conductive resistance of the condensate layer, or whether the conditions at the vapour–liquid interface are of importance. A need for further work in this field is obvious. The work described in this thesis covers the design and development of an apparatus to investigate the process of condensation of mixtures of vapours of immiscible liquids and an experimental study in which local heat transfer coefficients have been measured and related to visual observations of the condensate flow pattern.

The discovery of the hydrogen isotope, deuterium, was recognised as one of the most important events in the history of physical chemistry in the last twenty years. The comparatively large differences in the physical properties of the hydrogen isotopes and their compounds led immediately to the use of deuterium as an indicator and also as a tool -rith which to investigate the mechanisms of reactions involving hydrogen and its compounds. The commercial preparation of deuterium oxide ('heavy water') and its availability at a comparatively low price has enabled chemists to use this isotopic water in place of ordinary water. In the field of homogeneous catalysis this has been particularly advantageous and as the following work deals with homogeneous catalysis in isotopic water solutions I append a short summary of the work hitherto done and the relevant ideas held at present.

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This thesis describes cyclometallation at Pd, Mn and Co: functionalisation of C H and C≡C bonds involving cyclisation, rearrangement and isomerisation processes. The use of NaNO2/NaNO3 as an oxidant in oxidative Pd-catalyzed processes has recently been reported as a complementary co-catalyst to other common oxidants (e.g. CuII/AgI salts). In view of this (Chapter two) the synthesis of a series of palladacyclic complexes containing a C^N ligand backbone, and the geometry and linkage isomerism at NO2 Pd, has been studied. The geometry about the Pd(II) centre shows the crucial role played by bulky ligands in creating hindrance and affecting phosphine dissociation. Mn-catalysed C-H bond activation is a powerful strategy for the functionalisation of organic compounds containing metal-directing groups. Chapter three of this thesis reports the characterisation of a highly reactive 7-membered MnI species which acts as anvil point between protonation and reductive elimination to deliver alkenylated and/or pyridinium products respectively. Both processes are exemplified through the reactions of a substrate containing a 2-pyridyl directing group and electron-deficient 2-pyrone motif at MnI, where C-H bond activation occurs regioselectively at C3 within the 2-pyrone. An unprecedented regioselective Diels-Alder reaction also occurs on both the pyridine and 2-pyrone ring systems. These findings provide a unique insight into MnI-mediated C-H bond activation processes, especially how relatively minor changes in substrate structure influence the product distribution. The study shows that MnI-based metallocycles warrant further study more generally in organic and organometallic chemistry The intermolecular Pauson-Khand (PK) reactions of sterically comparable (2-pyridylethynyl)-heteroaromatic compounds with norbornene, mediated by Co2(CO)8 to give cyclopentenone products, were examined in Chapter four of this thesis. The π-deficient heteroaromatic substrate, 2-pyrone, favoured the -position while the π-rich heteroaromatics such as 2-thiophene favour the β-position. The position of the nitrogen in pyridyl-containing alkyne substrates also affects the regiochemical outcome of the PK reaction. A 2-pyridyl alkyne, possessing a proximal nitrogen atom, influences the regioselectivity relative to a 4-pyridyl variant, quite dramatically, favouring the β-position in the newly formed cyclopentenone ring. Overall, the type of heteroaromatic group greatly influences PK regioselectivity. The PK cycloadducts undergo a 6π-electrocyclisation–oxidative aromatisation reaction in the presence of light, which is promoted by a LED UV-light controlled system, affording benzo[h]indeno[1,2-f]isochromene type products.