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Abstract: Deep Eutectic Solvents (DES) are a recently-discovered category of potentially more sustainable alternative solvents. They are liquid eutectics formed upon the combination of various precursors, normally organic halide salts and neutral species. The most common DES is a 1:2 mixture of choline chloride:urea. DES are beginning to be used as non-aqueous alternative solvents for a variety of processes, such as synthesis of small molecules and materials, and electrodeposition. For the successful development and implementation of DES as a drop-in green solvent, it is important to build a strong fundamental understanding of the structure and properties. This will aid in the realisation of DES as ‘task-specific’ solvents which can be rationally tuned to fit the application of interest. There are several fundamental issues presently impeding the progression of the field of DES. Firstly, due to their similar properties and designer nature, DES are often presented as a sub-category of ionic liquids (ILs) though the combination of ionic and molecular species will yield a more structurally complex system, with contributions from electrostatic forces as well as H-bonding. In this thesis the structure of various DES has been explored primarily using neutron diffraction and atomistic modelling studies. These works showed evidence for a disordered and extensive H-bond network in the liquid rather than extensive ion complexation, which has important consequences for the design of chemical processes using DES. Overall, this thesis is a coherent body of independent systematic investigations into the solvent structure and solvation behaviour of DES, and synthesis of nanoparticles with wide-reaching environmental applications. We have built further upon the fundamental understanding of DES and have drawn comparison between systematic structural observations and the performance of DES in relevant applications. It is hoped that these findings will help with the onward development of DES as alternative solvents for efficient and sustainable future industrial technologies, which can make the world a cleaner place.

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Abstract: Heterogeneous catalyst materials, in particular supported metal nanoparticles, are hugely important in industrial processes such as emissions control technology. In order to design new catalyst materials with improved catalytic performance, the catalytic properties and mechanistic pathways must be well understood. The work presented in this thesis makes advances to operando spectroscopy methods for the characterisation of industrial heterogeneous catalyst materials operating in realistic reaction conditions. A multi-technique approach, employing XAFS and DRIFTS simultaneously, has been used to probe the electronic and structural properties of metal nanoparticles as well as the molecular vibrations of reactants and intermediates at the catalyst surface. In this work, the preparation of supported metal nanoparticle catalysts have been investigated using time-resolved XAFS and DRIFTS spectroscopy approach. Structure-activity relationships of the supported Pd nanoparticle catalysts have been identified during their operation for an important reaction used in diesel after-treatment technology; the selective catalytic oxidation of NH3. The selectivity of the reaction towards the different reaction products (N2, N2O and NO), within the relevant temperature window for industrial application, has been linked to the different structural phases of Pd, including a previously unidentified PdNx species. The major challenges for operando measurements, concerning improved time resolution and spatial resolution, have been addressed with the development of a new reactor for combined XAFS and DRIFTS of a catalyst bed operating in plug-flow reaction conditions. The advantage of this reactor design for operando characterisation has been demonstrated in the investigation of a supported Pd nanoparticle catalyst (Pd/γ-Al2O3) during oscillating CO oxidation. This reactor improves on previous designs by allowing spectroscopic measurements to be performed with spatial resolution along the axial length of a catalyst bed. In this way, there is scope for elucidating the structure-function relationships of many other heterogeneous catalysts.

Open Access

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Abstract: This manuscript presents the current status and technical details of the Spectroscopy Village at Diamond Light Source. The Village is formed of four beamlines: I18, B18, I20-Scanning and I20-EDE. The village provides the UK community with local access to a hard X-ray microprobe, a quick-scanning multi-purpose XAS beamline, a high-intensity beamline for X-ray absorption spectroscopy of dilute samples and X-ray emission spectroscopy, and an energy-dispersive extended X-ray absorption fine-structure beamline. The optics of B18, I20-scanning and I20-EDE are detailed; moreover, recent developments on the four beamlines, including new detector hardware and changes in acquisition software, are described.

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Abstract: The I20 beamline at Diamond Light Source (DLS) requires a set of vertical “turbo” slits which can be scanned across a horizontal x-ray fan. To achieve a fast scan rate, requires a precision slit mechanism which is both light weight and compact. The design solution is to use a 4 bar flexural hinge geometry. Several different approaches may be used to design / analyse flexural hinges, including equations based on a simplified model of the hinge, FEA analysis either of the hinge or a full FEA analysis of the overall design, empirical values based on previous designs and mechanism analysis. This case study then presents the approach used to design the hinge mechanism for the turbo slits, using simple analytic equations to obtain the moments and stresses at the hinge, “large” angle kinematic mechanism analysis to optimise the overall movements of the mechanism, correlation of hinge parameters to give the optimum design and validation of forces, stresses & strains using a full FEA model. The slit mechanism has been built and the deflection / load performance experimentally validated. The scanning mechanism incorporating the slits has been demonstrated in the laboratory.

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Abstract: The Versatile Spectroscopy beamline at Diamond Light Source, I20, is currently under construction and aims to begin operation in late 2009 and early 2010. The beamline aims to cover applications from physics, chemistry and biology through materials, environmental and geological science. Three very distinctive modes of operation will be offered at the beamline: scanning X-ray Absorption spectroscopy (XAS), XAS in dispersive mode, and X-ray emission spectroscopy (XES). To achieve this, the beamline has been designed around two independent experimental end-stations operating from a pair of canted wigglers located in a 5m diamond straight section. One branch of the beamline will deliver monochromatic x-ray radiation of high spectral purity to one of the experimental hutches, whilst the other branch will constitute an energy dispersive spectrometer. The novel design of the beamline allows both branches to operate simultaneously.