Ferrihydrite is a poorly crystalline iron (oxy)hydroxide which exists exclusively in a disordered nanocrystalline form. Lacking long range three-dimensional structural order, possessing a high density of defects and displaying variable composition depending on origin has meant that to date a clear consensus regarding a structural model has yet to be reached. A departure from traditional means of crystallographic investigation is therefore required prompting the exploration of hitherto unexplored and potentially novel methods in refining this elusive structure. Recent years have witnessed significant interest in the investigation of ferrihydrites formed in the presence of compounds such as phosphate and citrate. Novel forms of ferrihydrite have been reported, produced by the hydrothermal treatment of these modified ferrihydrites, which have the potential to increase understanding of ferrihydrite in general. This work demonstrates the application of the latest generation of aberration corrected electron microscopes to the structural and chemical characterisation of ferrihydrite produced both in vitro and within the protein cage of ferritin. Two-line ferrihydrite (2LFh), coprecipitated in the presence of varying concentrations of phosphorus (P-doped) and subject to hydrothermal and dry air annealing heat treatments, has also been investigated. By way of a thorough characterisation additional physicochemical characterisation techniques have been applied to confirm the phase purity of specimens and benchmark them against those reported in the literature. The effects of prolonged exposure to the 200 keV electron beam of the transmission electron microscope (TEM) has been investigated by the simultaneous acquisition of Fe-L and O-K edge electron energy-loss (EELS), EELS and energy dispersive X-ray (EDX) compositional and selected-area electron diffraction (SAED) data. A safe fluence level of 108 electrons nm-2 has been established, below which both 2LFh and P-doped 2LFh can be observed in their pristine state. Beyond the safe fluence limit alteration of both pristine 2LFh and the P-doped 2LFh proceeds by preferential loss of oxygen, reduction of iron and concomitant phase transformation to a material with characteristics similar to that of magnetite. A novel low-electron fluence method of scanning TEM EELS acquisition (SmartAcquisition) has been developed and its applicability to the characterisation of ferrihydrite nanoparticles proven. Results here are consistent with independently published data which confirm ferrihydrite to be a predominantly Fe(III) bearing iron-oxide material in which the iron atoms reside in six-fold coordination with oxygens and/or hydroxyls. Fe-L EELS edge analysis provides support for a new and controversial model for the structure of ferrihydrite in which a significant fraction of iron is in four fold coordination. High-angle aberration corrected scanning electron microscopy is used to investigate the morphology of ferritin mineral cores. Atomically resolved sub-unit structure is observed with individual cores comprising several crystalline units which appear to have nucleated independently of one another. The principle aim of this work it to explore the applicability of the latest generation of analytical electron microscopes for the elucidation of chemical and structural properties of challenging nanoparticulate systems.

Chemical looping steam reforming (CLSR) and sorption enhanced chemical looping steam reforming (SE-CLSR) were utilised as process intensification measures to optimise the steam reforming process of acetic acid as a base-case for the enhanced steam reforming of pyrolysis oils. Both processes were carried out in a packed bed reactor, using two conventional nickel-based catalysts (‘A’ with alumina support and ‘B’ with calcium aluminate support) with the view of ascertaining optimal conditions for sustained steam reforming, and observing changes in morphology and characteristics in the materials utilised. An experimental review, carried out on the steam reforming of acetic acid indicates, an acetic acid and water pre-heat temperature < 70°C and > 120°C respectively is ideal for sustained hydrogen production, at weight hourly space velocity (WHSV) set between 2.3 hr-1 to 2.5 hr-1, steam reforming temperature (TSR) set to 600°C or 650°C and steam to carbon ratio (S/C) set to 3 for the reactor set up and configuration utilised. Sustained steam reforming was observed at all TSR investigated (550°C – 700°C), at all catalyst sizes compared, and all WHSV utilised (2.1 hr-1 to 2.8 hr-1), with acetic acid conversion efficiency >83% realised and a hydrogen yield efficiency >85% realised for all experimental runs when compared to equilibrium values. Characterisation of the utilised catalyst through SEM images indicates the formation of filamentous carbon on the catalyst surface. Two peaks of CO2 obtained from the CO2 chemigram in TGA-FTIR analysis indicates two types of carbon are formed, with amorphous carbon and a polycrystalline pseudo-graphitic carbon observed through TEM images and diffraction patterns. CLSR has been promoted as a viable measure of improving the efficiency of the steam reforming process. It is a cyclic process that incorporates an oxidation step for material regeneration alongside steam reforming. In this study, it was inferred that the proficiency of the subsequent steam reforming fuel-steam feed run is dependent on the operating conditions and type of materials utilised in the oxidation step. Efficient auto-reduction and sustained CLSR close to equilibrium values were observed for both catalysts (S/C of 3, WHSV: 2.36 hr-1 and 2.5 hr-1, TOX: 600°C - 800°C, TSR: 600 °C and 650°C) except when oxidation was carried out at 600°C for catalyst A. This exemplifies the advantages of an alkali-based support for reforming catalysts such as the one in catalyst B in reducing thermal decomposition of the fuel and sintering. Study on TOX utilised indicates, an increase in TOX would lead to more efficient carbon and nickel oxidation. Care must be taken however because it also leads to a potential increase of sintering of the catalyst. SEM-EDX analysis and CHN analysis in this study indicates, there is a close similarity between the oxidised catalyst and fresh as received catalyst B particularly when oxidation is carried out at 800°C. This indicates complete burning of carbon and catalyst oxidation during the oxidation phase utilised for the CLSR experiments. The complete oxidation observed ensured sustained steam reforming over 10 cycles of CLSR investigated in this study (TSR at 650°C, TOX: 800°C, WHSV set to 2.5 hr -1and S/C of 3) for catalyst B. The sustained reforming, across all 10 cycles of CLSR, showed high consistency with >95% of acetic acid converted leading to a hydrogen yield efficiency >88% observed across all 10 cycles, when compared with equilibrium values. A carbon balance of the overall chemical looping reforming process infers most of the carbon share (ca 90%) in the process is utilised for effective steam reforming and hydrogen production. SE-CLSR entails the addition of a sorbent into the chemical looping reforming material bed. This has been promoted to lead to an increase in hydrogen concentration and yield, due to the shift in equilibrium towards hydrogen production caused by the in-situ carbon-capture during the reforming process. Two stages occur, as in the case of CLSR. Calcining of the sorbent occurs in the oxidation stage alongside other processes that occur in the oxidation step in CLSR. In-situ carbon capture or carbonation of the calcined sorbent occurs alongside other reactions in the reforming stage. Three phases were identified for the SE-CLSR reforming stage; The pre-breakthrough phase, where complete sorption activity occurs and >99% of all carbon products produced is captured. The breakthrough phase where a break of CO2 is observed indicating partial sorption activity. The post-breakthrough phase where no sorption activity is occurring. It was inferred that the mass of the sorbent added to the material bed has an influence on the carbonation duration (pre-breakthrough + breakthrough Phase). An increase in the sorbent/ catalyst ratio increases the duration of carbonation and number of moles of carbon captured. 20 cycles of SE-CLSR with TSR at 650°C and TOX set to 850°C using catalyst B with S/C set to 3 and WHSV set to 1.18 was conducted. Sustained and consistent reforming (>80 % of acetic acid converted) was observed across all 20 SE-CLSR cycles; this led to > 78% hydrogen yield efficiency across all 20 SE-CLSR cycles when compared to equilibrium values. A close observation of the carbonation duration indicates a reduction in the pre-break duration for the first 10 cycles. This led to a decrease in sorbent conversion and efficiency. This was attributed to a change in kinetics and CO2 capture capacity in the pre-breakthrough phase, caused by sintering in the materials and reduction of open porosity. At the end of the 20th cycle, the conversion efficiency had dropped to about 50% of the conversion efficiency at the end of the first cycle. This prompts the need for reactivation techniques to reduce the decay of the CaO sorbent across redox cycling. Steam hydration of the material has been promoted to improve the reactivity of CaO based sorbents and was carried out at 250°C with the view to observe any changes in the conversion of the sorbent. It was observed that on comparison to the SE-CLSR experiments with no hydration at 250°C, there was a higher hydrogen yield and concentration. This was attributed to a higher rate of sorption enhancement as observed in the increased carbonation rate in the pre-breakthrough phase for the experiments with hydration set at 250°C. There is also increased sorption enhanced auto-reduction observed and an improved sorbent conversion outlook over the cycles investigated.

This thesis focused on the fabrication and characterisation of an adaptable plasmonic platform consisting of a regular array of vertically aligned gold nanorods, supported on a gold substrate. The research aimed to understand the optical properties of the array, with particular emphasis on determining the coupling effects between the plasmonic nanorods. Characterisation was performed, both in the near and far-field, by means of optical spectroscopy, finite element modelling (FEM) and electron energy loss spectroscopy (EELS). The work subsequently aimed to use the knowledge gained from characterisation to optimise the absorption of visible light and enhancement of the electric-fields surrounding the plasmonic nanoparticles by controlling the geometrical factors of the array. Lastly, the nanorod arrays were then utilised for photocatalytic applications following their coating in a semiconductor material. During this research, gold nanorod arrays were successfully fabricated by means of electrodeposition in anodic aluminium oxide (AAO) membranes, with accurate control over the geometrical factors. UV-Vis measurements revealed that coupling within the array resulted in the higher wavelength longitudinal mode of the nanorods blue-shifting considerably to occur within the visible spectrum. For short aspect ratio (AR) nanorods, this mode overlapped with that of the transverse mode, however for longer ARs the mode could be tuned throughout the visible spectrum. This was in agreement with FEM results, however, it was additionally revealed that strongly coupled nanorod arrays undergo a redistribution in their electric field from localisation at the end of the nanorods, to one within the middle or base of the nanorods for unsupported and supported arrays respectively. It was further found that the presence of the substrate led to the nanorods coupling with their substrate image leading to greatly red-shifted resonances. Through experimental EELS measurements it was confirmed that this red-shift is due to coupling with the substrate, in addition to further analysing the particle coupling effects for both dimers, and larger arrays of nanorods. It was found that for dimers with strong coupling the longitudinal mode splits into both a bright mode with symmetrically aligned dipoles, and a dark mode with anti-symmetrically aligned dipoles, thereby agreeing with plasmon hybridisation theory. Furthermore, as the number of particles within the array increases, the modes split to form hybridised bright and dark modes consisting of elements of each. An initial attempt at photocatalysis was also performed based on the degradation of methylene blue by injection of hot-electrons into TiO2. No significant increase in activity was found, attributed to the semiconductor layer completely covering the nanorods thereby not allowing available sites for the oxidation reaction to replenish lost electrons in the metal.

As part of the UK’s energy system transition to a low-carbon electricity supply, decentralised energy sources such as small and medium scale wind turbines have become increasingly relevant. Decentralised energy generation has a central role in a proposed societal pathway to deliver a low-carbon energy system transition. Given the vast onshore wind energy potential of Great Britain, small and medium scale wind turbines will be a key part in this transition. With the introduction of the Feed-in Tariff (FIT) in April 2010, small and medium scale wind turbine deployment was expected to increase towards the technical potential of the technology, estimated to be up to 400,000 turbines. However, only 6,000 wind turbines have been installed in Great Britain since April 2010, highlighting there is still significant potential for small and medium scale wind turbine deployment. To fulfil this potential, an understanding of the influencing factors on previous wind turbine adoptions is required. A key part of this analysis is an investigation of the wind resource assessment methodology prescribed in the FIT policy. The Microgeneration Certification Scheme (MCS) is designed to offer a low-cost and quick scoping tool for prospective wind turbine installations. Analysis carried out in this work shows that long-term mean near surface wind speed predictions from the MCS method have a mean percentage error of 2.36 %. Over the same sample of 124 sites across Great Britain, a Boundary Layer Scaling (BLS) method, developed in this work, using UK wind map data offered wind speed predictions with a mean percentage error of 1.43 %. While these errors appear small, they equate, in the most extreme cases, to a difference of over £500 in annual FIT payments for a single wind turbine. While the MCS method is mandated in the FIT accreditation process, there is a risk that the potential financial returns of an installation can be severely miscalculated. Using the more accurate wind speed predictions available from the BLS model, it is possible to understand the influence of available wind resource on wind turbine adoption patterns. Throughout this work, wind turbine adoptions in Great Britain from 1995 until 2015 at both local authority and statistical geography resolution were analysed. Using a regression model, it is shown that wind resource explains up to 34 % of the spatial variance in adoption patterns. A threshold wind speed of 4.5 ms−1, above which wind turbine deployment is likely, was found in the current adoption patterns. These results highlight that while wind resource is an important factor, it is not the sole factor which influences wind turbine deployment in Great Britain. Previous literature has identified a number of socio-economic factors that have influenced adopters of other microgeneration technologies. Using a regression model and additional variables, such as land availability and agricultural statistics, it is possible to understand the influence of these socio-economic factors on wind turbine adoption patterns. The Socio-Economic and Resource (SER) model developed in this work highlights that wind turbine adoptions are more likely to occur in rural areas where wind resource, availability of land and prevalence of agriculture are high. Wind adopters are more likely to be older, hold degree-level qualifications and live in a detached home. This regression model however, only accounts for up to 65 % of the spatial variance in adoption patterns. This is an improvement over using only the resource model, however, there are still additional factors which influence wind turbine adoption patterns. The additional factors examined in this research were the influence from changes to the subsidy level of the FIT and the potential visibility of neighbouring turbines on adoption patterns. The visibility of neighbouring microgeneration installations has been cited as a factor which raises awareness in adopters, a factor particularly prevalent to wind turbines, which are highly visible to close neighbours. The influence of these factors was examined using a peer effects model in areas of high installations. The model shows that reductions in the FIT subsidy level have severely affected deployment. A peer effect from visible neighbouring turbines can be seen in these clusters of installations, however, it is secondary to the level of FIT subsidy available. In some clusters, evidence for a slow diffusion of wind turbines between peers was observed. Overall, the model indicates that the subsidy level available from the FIT was more influential than the visual peer effects. However, it is anticipated that this peer effect, will increase as deployment increases. In conclusion, the research has found that adoptions of wind turbines in Great Britain are influenced by a number of factors, namely available wind resource, rurality of turbine location, income of individual adopters and the subsidy level available for energy generation. These findings indicate that the small and medium scale wind turbine market in Great Britain is approaching a critical stage in its adoption lifecycle. Additionally, the results were used to develop a number of potential deployment estimates to understand where future growth in the market may occur. To meet these potential deployment estimates, there needs to be higher levels of deployment in order to help reduce capital costs. To achieve this future deployment, the levels of subsidy available from the FIT need to be maintained, in addition to the introduction of a BLS methodology in the FIT policy to facilitate more accurate financial assessments. A reduction in capital costs and maintaining of FIT subsidies will increase the number of sites which are financially viable for wind turbine installation. Potential new sites must still have a sufficient long-term mean wind resource of 4.5 ms−1 or above to be economically viable, highlighting the need for the introduction of the more accurate BLS methodology. If these conditions occur, deployment of small and medium scale wind turbines can increase towards the technical potential and play a central role in the transition to a low-carbon electricity market in Great Britain.

The solutions for mitigating climate change are diverse, ranging from innovative technological advancements to national and international policy mechanisms, aimed at behavioural changes. Although rudimentary, the use of wood biomass in energy generation – as an important short- to mid-term transitional fuel – has continued to grow, forming a key component of global mitigation strategies. This is particularly apparent in the UK, which relies upon large volumes of imported wood pellets to supplement home-grown feedstocks. As the UK’s forest resource is relatively small – when compared to the rest of Europe – the governments recently proposed afforestation schemes should prove beneficial; however, before initiating any major tree planting scheme, it is important to first fully understand the existing resource. This interdisciplinary research – exemplifying the diverse nature of forestry – has investigated the UK’s current forest feedstocks, focusing on samples sourced from different tree sections of UK-grown oak, birch, Scots pine and Sitka spruce. Their fundamental characteristics have been analysed, including the completion of Proximate, Ultimate and Lignocellulosic analysis, and the determination of their calorific values. Utilising these results – alongside data collated from extensive literature sources – the statistically significant differences that exist between wood feedstocks have been defined, inferring relationships that link their elemental, chemical and structural components. Consequently, the known heterogeneity of wood – and how this differs between species and tree sections – has been demonstrated, specific to UK-grown wood species. These differences can have both negative and positive impacts upon woodfuel quality and the forest environment, particularly in relation to the blending of residues and stump wood with stem wood. In the case of UK-grown birch and Sitka spruce this could increase the volume and energy content of the produced woodfuel, however it will also result in a more reactive fuel, containing increased contents of nitrogen and potassium. An investigation into the costs of felling and extracting wood from UK forests – incorporating geospatial analysis of the UK’s existing feedstocks – suggests it is currently economically viable to increase the supply of woodfuel from the nation’s forests. This could produce an estimated 2,645 TJ yr ̄1 of additional energy, specifically for domestic use in rural locations, situated close to the UK’s forest resource. Although the continued expansion of the UK’s woodfuel market is viable, it is important that the profitable production of fuel is balanced with the continued protection of our forest environments.

Endohedral nitrogen fullerenes (ENFs) have been proposed as building blocks for quantum information processing due to very long relaxation time for their incarcerated electron spins. However, fabricating quantum devices based on this exotic material is still limited by the low yield of ENFs synthesis and various difficulties in subsequent molecular engineering, including the chemical sensitivity of the molecules, assembling approaches of the molecular architecture, and control of spin-spin coupling between qubits. My contributions towards removing the aforementioned limitations by studying the synthesis and functionalisation of ENFs are presented herein. My aim has been to pave the way towards quantum devices based on ENFs. Firstly, I enhanced the ENFs production yield by a factor of five. I accomplished this by optimizing the ion implantation apparatus and parameters during the synthesis of raw ENFs, in addition to adjusting the column and eluent during the purification of ENFs by high performance liquid chromatography (HPLC). Secondly, I established (for the first time) a spin-compatible protocol for performing Bingel reactions on ENFs. Utilizing the developed method, I also demonstrated the feasibility of chemically modifying ENFs for different molecular requirements via synthesizing a series of ENF derivatives with rigid configuration, long molecular aspect ratio, and amphiphilic properties. Subsequently, I covalently assembled ENFs at microscopic levels and axially aligned ENFs at macroscopic levels, respectively. At the microscopic scale, I synthesized ENF- containing dyads and dimers, and developed a method of coaxially dimerizing ENFs with rigid bridge molecules, which provides material foundation for multi-qubit manipulations with spin couplings. At the macroscopic scale, I achieved the best orientational alignment of ENFs reported to date by embedding elongated ENF derivatives within a liquid crystal, which is critical for ensemble qubit with anisotropic spin properties. Benefiting from the good alignment, a controllability of the ensemble spin anisotropy is demonstrated with zero-field splitting of ENF derivatives. Finally, I studied the electron spin dipolar coupling in ENFs by measuring and comparing of the coupling strength at different conditions. I discovered that the electron spin dipolar coupling in N@C60-CuPc dyads can be chemically tuned by altering the lengths of the spacing groups between the two spin centres, and be physically adjusted by changing the sample concentrations to aggregate the sample and suppress the Cu electron spin. In summary, aiming for ENF-based quantum devices, I made progress in both the material production and the molecular engineering of ENFs.

High-intensity focused ultrasound (HIFU) therapy is a non-invasive therapy method for the treatment of solid tumours. One of the main barriers to wider clinical adoption of HIFU is the lack of reliable and cost-efficient therapy monitoring. One promising technique is acoustic radiation force (ARF) ultrasound elastography, which relies on the temperature dependence of tissue properties to affect displacement amplitudes. An extensive literature review of tissue acoustic, thermal and mechanical properties identified an absence of data on the temperature dependence of the viscoelastic properties. Experiments were carried out in ex vivo liver to determine these properties over the range of temperatures and frequencies relevant to ARF. ARF induced displacements were quantified experimentally in a tissue-mimicking phantom. The comparison of sine and square modulated ARF excitation showed that square modulation results in higher peak amplitudes and smaller second harmonic components in the frequency domain. A simulation model was developed, which accurately reproduced the observed displacements with different modulation frequencies and power levels. The effect of temperature on ARF displacements was measured experimentally during HIFU therapy in ex vivo liver. Simulations captured the same phenomena as observed in the experiments. ARF displacements during HIFU therapy were shown to initially depend on attenuation before ablation, but once the temperature exceeded the ablation threshold, viscoelastic properties dominated. A second barrier for HIFU is the need to reliably deliver acoustic energy to the target. Nonlinear acoustic simulations were conducted using patient derived computed tomography (CT) data to evaluate the HIFU therapy in the kidney. The simulations revealed that attenuation and refraction contributed roughly equally to intensity loss. Focal splitting associated with refraction was found to be the main effect reducing the heating efficacy, and a method to employ phase correction at the source was proposed to mitigate the effect.

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