Engineered manganese oxide nanomaterials for the control of oxygen - from catalysts to biology

Many have noted that "disordered metal oxides" can be highly efficient catalysts for water oxidation. Interestingly, "disordered metal oxides" are also observed to be highly reactive and have unusual properties in some biological and environmental systems too. In this work we systematically explore the impact of structural disorder on different types of reactivity. A test set of Manganese (III, IV) oxides were used through the thesis to systematically explore differences in catalytic efficiency, redox efficiency and biological activity. The thesis is set out in a way that addresses each of these issues. We start with the synthesis and characterisation of a "test set" of manganese oxides, then develop an assay that examines the effect of disorder on thermodynamics. Concluding that disorder has the effect of destabilising the materials thermodynamically. The second results chapter explores the relationship between "redox chemistry" and "catalytic chemistry" we find that the two phenomena are closely related however, that the time scales of a redox reaction (being slow) and a catalysis reaction (being fast) fundamentally separate them. The final chapter explores the effect of disorder on antibacterial activity. A strong correlations between the biological and chemical observations find being that the disordered manganese oxides have substantially more antimicrobial activity than their more ordered cousins. In summary, it was found that disorder has a destabilising effect on manganese oxides that significantly impacts their reactivity, whether as oxidants, catalysts or as antimicrobial agents. Engineering disorder into materials may provide a new pathway in material design not previously recognised.