Nanostructured Metal Oxide Coatings for Electrochemical Energy Conversion and Storage Electrodes

The realization of an energy future based on safe, clean, sustainable, and economically viable technologies is one of the grand challenges facing modern society. Electrochemical energy technologies underpin the potential success of this effort to divert energy sources away from fossil fuels, whether one considers alternative energy conversion strategies through photoelectrochemical (PEC) production of chemical fuels or fuel cells run with sustainable hydrogen, or energy storage strategies, such as in batteries and supercapacitors. This dissertation builds on recent advances in nanomaterials design, synthesis, and characterization to develop novel electrodes that can electrochemically convert and store energy.

Chapter 2 of this dissertation focuses on refining the properties of TiO2-based PEC water-splitting photoanodes used for the direct electrochemical conversion of solar energy into hydrogen fuel. The approach utilized atomic layer deposition (ALD); a growth process uniquely suited for the conformal and uniform deposition of thin films with angstrom-level thickness precision. ALD’s thickness control enabled a better understanding of how the effects of nitrogen doping via NH3 annealing treatments, used to reduce TiO2’s bandgap, can have a strong dependence on TiO2’s thickness and crystalline quality. In addition, it was found that some of the negative effects on the PEC performance typically associated with N-doped TiO2 could be mitigated if the NH3-annealing was directly preceded by an air-annealing step, especially for ultrathin (i.e., < 10 nm) TiO2 films. ALD was also used to conformally coat an ultraporous conductive fluorine-doped tin oxide nanoparticle (nanoFTO) scaffold with an ultrathin layer of TiO2. The integration of these ultrathin films and the oxide nanoparticles resulted in a heteronanostructure design with excellent PEC water oxidation photocurrents (0.7 mA/cm2 at 0 V vs. Ag/AgCl) and charge transfer efficiency.

In Chapter 3, two innovative nanoarchitectures were engineered in order to enhance the pseudocapacitive energy storage of next generation supercapacitor electrodes. The morphology and quantity of MnO2 electrodeposits was controlled by adjusting the density of graphene foliates on a novel graphenated carbon nanotube (g-CNT) scaffold. This control enabled the nanocomposite supercapacitor electrode to reach a capacitance of 640 F/g, under MnO2 specific mass loading conditions (2.3 mg/cm2) that are higher than previously reported. In the second engineered nanoarchitecture, the electrochemical energy storage properties of a transparent electrode based on a network of solution-processed Cu/Ni cores/shell nanowires (NWs) were activated by electrochemically converting the Ni metal shell into Ni(OH)2. Furthermore, an adjustment of the molar percentage of Ni plated onto the Cu NWs was found to result in a tradeoff between capacitance, transmittance, and stability of the resulting nickel hydroxide-based electrode. The nominal area capacitance and power performance results obtained for this Cu/Ni(OH)2 transparent electrode demonstrates that it has significant potential as a hybrid supercapacitor electrode for integration into cutting edge flexible and transparent electronic devices.

Plato's Cretan Colony: Theology and Religion in the Political Philosophy of the Laws

The Laws is generally regarded as Plato’s attempt to engage with the practical realities of political life, as opposed to the more idealistic, or utopian, vision of the Republic. Yet modern scholars have often felt disquieted at the central role of religion in the Laws’ second-best city and regime. There are essentially the two dominant interpretations on offer today: either religion supports a repressive theocracy, which controls every aspect of the citizens’ lives to such an extent that even philosophy itself is discouraged, or religion is an example of the kind of noble lie, which the philosopher must deceive the citizens into believing—viz., that a god, not a man, is the author of the regime’s laws. I argue that neither of these interpretations do justice to the dialogue’s intricately dramatic structure, and therefore to Plato’s treatment of civil religion. What I propose is a third position in which Plato both takes seriously the social and political utility of religion, and views theology as a legitimate, and even necessary, subject of philosophical inquiry without going so far as to advocate theocracy as the second best form of regime.

I conclude that a proper focus on the dialogue form, combined with a careful historical analysis of Plato’s use of social and political institutions, reveals an innovative yet traditional form of civil religion, purified of the harmful influence of the poets, based on the authority of the oracle at Delphi, and grounded on a philosophical conception of god as the eternal source of order, wisdom, and all that is good. Through a union of traditional Delphic theology and Platonic natural theology, Plato gives the city of the Laws a common cult acceptable to philosopher and non-philosopher alike, and thus, not only bridges the gap between religion and philosophy, but also creates a sense of community, political identity, and social harmony—the prerequisites for political order and stability. The political theology of the Laws, therefore, provides a rational defense of the rule of law (νόμος) re-conceived as the application of divine Reason (νοῦς) to human affairs.