A computational and experimental study of alternative energy technologies: Constructing photochemical electron-transfer cascades and the development of computational methods for understanding fuel cell electrocatalysts

Producing viable, vertically-integrated alternative energy systems requires solving chemical and engineering problems at many levels. This work presents experimental results seeking to make visible light driven water splitting more feasible, computational efforts aiding in the combinatorial screening of fuel cell catalysts, and a physically-realistic model of the electrochemistry at porous electrode surfaces to understand and improve the porous electrodes used in fuel cells.; Combinatorial chemistry is a valuable technique for developing and screening large quantities of candidate catalysts. Data obtained from such experiments can be difficult to analyze and communicate. We implement a system to identify catalytically-active clusters within data sets and to compactly visualize four and five-metal catalytic compositions graphically as tetrahedra or animations.; Combinatorially-determined catalysts are often deposited on porous electrodes providing high surface area supports for many reactions, but the influences of electrode preparation conditions on electrocatalysts are not always well understood. Electrochemical impedance spectroscopy (EIS) can provide extensive information about an electrode, but idealized models describing spectra limit the ability to draw useful conclusions. We describe a new model based on an array of parallel, non-uniform transmission lines for predicting the response of porous electrodes. The model incorporates physically realistic elements, such as discrete particles of variable size and adjustable multi-layer stacking geometries. Resistance parameters were derived from experimental data for Pt₄Ru₄Ir coated Ti_0.9Nb_0.1O ₂ and Ebonex electrodes prepared under varying degrees of oxidative conditioning. The results, which indicate a high degree of impedance at the support-solution interface and consequently low catalyst utilization, suggest several strategies for improved electrode design.; Fuel cells' popularity, however, is limited by the cost of their fuels. Visible light photolysis of water could supply hydrogen abundantly, but each of the possible solutions to this challenge possess major drawbacks. When using inexpensive, sensitized, self-assembled inorganic systems, efficiency suffers from short charge-separated states and frequent recombinations. This work seeks to prolong charge-separated state lifetimes by constructing inorganic staircases of decreasing conduction band potentials down which photoelectrons may descend. A series of short, energetically favorable hops should prolong lifetimes. After developing a novel high-surface area support, lifetime enhancements of up to 15% were observed.