Graphene is well-known for its exceptional mechanical, electrical, and thermal properties, but its potential is yet to be fully realised in bulk applications due to difficulties in obtaining a large yield of high-quality individually-dispersed graphene sheets. In this thesis, reductive exfoliation of bulk graphite is demonstrated as a promising and versatile method which allows the isolation of single- and few-layer graphenes; the production of reduced graphene, or ‘graphenide’, solutions shows varying efficiency in different solvents. Subsequent functionalisation of graphenide dispersions with various electrophiles, including 1-bromododecane, anionic monomers such as methyl methacrylate, and bromine, results in increased solubility in organic solvents, without damage to the graphene basal plane. Exact characterisation and quantification of grafting is complicated by the presence of solvent remaining between graphene layers, a phenomenon which is not significant in other carbon nanomaterials. Reductive alkylation was carried out on five different graphitic starting materials including two types of natural flake graphite, shear-exfoliated graphite platelets, graphite nanofibres, and few-layer graphene. The study reveals pronounced differences in the obtained grafted species with respect to the degree of functionalisation and residual solvent, exfoliation efficiency and product homogeneity. These results are shown to be dependent on the size and nature of the starting material, with few-layer graphene showing the highest grafting ratios. Few-layer graphene was also functionalised with various molecular weight poly(methyl methacrylate) (PMMA) polymers by grafting-to and grafting-from approaches; the grafting ratios were higher for the grafting-from approach and the products showed a far greater dispersibility in acetone (up to 920 µg/mL). In parallel with these direct polymer-grafting strategies on few-layer graphene, the reduction method was used to dissolve and brominate few-layer graphene sheets, achieving direct covalent attachment of bromine to the graphene framework. The brominated few-layer graphenes provide a convenient, stable, liquid-phase precursor, suitable for the synthesis of a variety of directly functionalised graphenes. As an example, the brominated species was used to initiate atom transfer radical polymerisation, to obtain PMMA-grafted graphene, which was six times more dispersible in acetone than controls. In addition, brominated graphene is active for nucleophilic substitution reactions, as illustrated by the preparation of methoxypolyethylene glycol- and hydroxyl-substituted derivatives. Grafting ratios for these polymer-functionalised materials varied between 6 and 25% and all graphene derivatives showed increased solubility in organic solvents, highlighting the potential of this route for preparing large quantities of dispersed graphene with minimal damage to the carbon framework.

This investigation concerns the corrosion of alumino-silicates by V205/Na2SO4 melts. A testing apparatus was designed and built whereby molten salts passed through a refractory tube at a constant rate under streamline conditions. For this system a theoretical equation, the Leveque relationship, may be derived. This involves the amount of refractory dissolved, with other variables, including its diffusion coefficient and the driving force. The relationship was tested in a model experiment at ambient temperatures and was obeyed over a wide range of test conditions except for a constant factor discrepancy, thought to be due to activity effects. Solubility experiments conducted to ascertain the magnitude of the driving force indicated that whereas alumina was relatively insoluble in all melts the silica was very soluble. This work also shewed published work on fusion temperatures to be wrong and the hypothesis of the fusion mechanism of corrosion by NaV03 to be unlikely. The first flow experiments shewed the dissolution of alumina to be intermediate between diffusion and reaction control. Silica corrosion was diffusion controlled. Comparisons indicated that silica was marginally superior at lower soda concentrations but with higher soda additions at higher temperatures alumina was far more corrosion resistant. Under stagnant conditions alumina would always be superior. The slagging of mullite appeared to remove silica leaving a more resistant alumina surface layer. Calculations on the size of the diffusing silica species indicated that in pure V205 at 721°C it consisted of approximately 1.4 x 105 molecules. There was strong evidence that increased melt corrosivity with higher soda additions was due to a progressive reduction in the SiO2 macro-molecule size, single SiO2 units being attained at 900C in the equimolecular melt. It was inferred that the progressive breakdown of the macro-molecule was a temperature activated process. The design of a flow apparatus operable no to 1600°C has been discussed in detail.

The conversion of dinitrogen to ammonia is a fundamental process for sustaining life on our planet. Ammonia provides a source of fixed nitrogen for nitrification and assimilation into plants, and is the ultimate source of almost all nitrogenated compounds. Synthetic ammonia is produced on a colossal scale by the Haber Bosch process, with an annual ammonia output exceeding 130 million tonnes. However, the intensive operating conditions of this process require a staggering energy cost; hence, the development of a lower energy solution is recognised as one of the major challenges of modern chemistry. This dissertation explores the chemistry of homogeneous systems based on iron diphosphine complexes that are able to transform coordinated dinitrogen into ammonia. A greater understanding of these systems may provide insight into the iron-based catalysts utilised in both biological nitrogen fixation and the industrial Haber Bosch process. Ultimately, this could lead to a more sustainable process for meeting the global requirement for fixed nitrogen. Chapter 1 provides a general introduction into dinitrogen fixation chemistry, with a particular focus on homogeneous systems involving iron. Chapter 2 describes a convenient synthetic protocol to 1,2-bis(dialkylphosphino)ethanes. These are among the most versatile ligands used in inorganic chemistry, although issues with prior syntheses, often involving extremely hazardous phosphine precursors, has limited their accessibility. Chapter 3 is an exploration of a seminal work on dinitrogen fixation involving iron complexes, which facilitate the conversion of coordinated dinitrogen to ammonia in what is known as the Leigh cycle. Mechanistic understanding of the key ammonia producing step has provided the focus of considerable interest and speculation for over a decade. Chapter 4 provides insight into the dinitrogen and dihydrogen affinity of an iron(I) complex. Chapter 5 details the experimental procedures performed in this work.

Carbon dioxide capture is an urgently needed pathway to mitigation of climate change, yet the amine-based solvents currently considered the leading industrial technologies suffer from many shortcomings; namely their high operating cost, poor stability and potentially damaging environmental impact from emission of degradation products. This work is a study of possible routes to improved CO2 capture technologies from a fundamental chemistry perspective. Initial work focused on the development of a straightforward and adaptable protocol for studying the species formed by CO2 capture into amine solvents, using 1H NMR spectroscopy for its combination of speed and accuracy. The applicability of this approach to diverse blended-amine solvents was demonstrated. This method was then applied to the study of phenoxide as a novel possible capture agent in conjunction with amines. Blends of potassium phenoxide with monoethanolamine were found to have an excellent capture capacity and favourable speciation that suggests a low energy consumption in practical use. This demonstrates the feasibility of blended solvents with a reduced amine component. Finally, a possible amine-free route to CO2 capture, exploiting the high susceptibility of carboxylate acidity to solvation, was explored. The first systematic study of the pKa of CO2 in mixtures of organic solvent and water was carried out, finding that this value is relatively insensitive to the makeup of the solvent and therefore in organic-rich solutions, carboxylate salts can be used as a CO2-absorbing base. CO2 capture using a system developed along these principles was demonstrated, and the possible basis for the observed insensitivity was discussed with particular emphasis given to the thermodynamics of the process.

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A series of measurements of stable nickel isotopes were performed at the Australian National University in Canberra. Excited states in 58,60,62Ni were populated via inelastic scattering of proton beams delivered by the 14UD Pelletron accelerator. Multiple setups were used in order to determine the structure of low-lying states. The CAESAR array of Compton-suppressed HPGe detectors was used to measure the (E2/M1) mixing ratio of transitions from angular distributions of gamma rays. The Super-e spectrometer was used to measure conversion coefficients for a number of J to J transitions. The data obtained from both devices was combined with previously measured parent lifetimes and branching ratios to determine E0 transition strengths between J-pi transitions. The E0 transition strength for the second 0+ to first 0+ transitions in 60,62Ni have been measured for the first time through internal conversion electron detection. The experimental value of 132(+59,-70) for 62Ni agrees within 2 sigma of the previous result obtained from internal pair formation. However it is likely that the previous experimental results used an outdated theoretical model for internal pair formation emission. This work also represents the first measurements of E0 transition strengths between 2+ states in Ni isotopes. There is generally large E0 strength between the 2+ states, particularly in the second 2+ to first 2+ transition, however there is also a large uncertainty in the measurements owing to the difficulties involved in measuring conversion coefficients. In 62Ni, the E0 transition strength of 172(+62,-77) for the second 2+ to first 2+ transition gives further weight to the argument against the spherical vibrator model, as an E0 transition is forbidden if there is a change of only one phonon. The large measurement also indicates the presence of shape coexistence, complementing the recent experimental work carried out in the neutron-rich Ni isotopes.

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