Exploring structural effects in oxygen evolution catalysis [electronic resource]

Sustainable access to electricity represents one of the largest challenges of the 21st century. The current paradigm of centralized infrastructure may not alone be sufficient, particularly as we consider some of the most under-served areas of the world. Further, we cannot continue to rely on continued supply of affordable fossil fuels. Here we use density functional theory (DFT) calculations to model the electrochemical transformations of water and energy to allow communities to independently and sustainably make the most of their locally available resources. "Splitting" water into component hydrogen and oxygen gasses is a promising method of energy storage that may also provide separation from some contaminants. Current water splitting technology is inefficient and has remained so despite decades of work in catalyst design and development. In the first section (Chapter 3) we propose a model system that seeks to overcome these efficiency limits by introducing confinement effects that specifically target only one reactive intermediate. We report a reduced theoretical overpotential (increased catalytic efficiency) for some materials, and provide intuition for which materials are likely to benefit from similar effects. In the second section (Chapter 4) we generalize the model presented in Chapter 3 to a more experimentally accessible system. We study oxyhydroxide catalysts which naturally intercalate water under water splitting conditions, and we consider the possibility that these intercalated water molecules may be reactive. We report phenomenologically similar behavior as in our model systems, and suggest that experimentally measured activity for these systems may include some contribution from "bulk-like" sites reacting with intercalated water. The aforementioned results obtained from DFT, especially for oxyhydroxides, require some methodological scrutiny. In the third section (Chapter 5) we work with collaborators to bench- mark our calculation schemes against a carefully-controlled experimental reference for adsorption energy. We find exceptional agreement in the low-coverage regime and discuss the potential sources for and implications of our discord at higher coverages. In the last section (Chapter 6) we present a scheme for accelerating calculations like those done throughout this work. We present the idea that tools emerging from data science can supplement traditional ab-initio methods to allow us to focus our computational resources in areas of phase space that are most likely to be applicable to the problem(s) at hand. We begin to work through an example of this technique, and highlight the necessary decisions made during model development. In summary this work uses theoretical tools to approach challenges in device efficiency that could lead to grid-independent energy and water solutions for developing communities. We demonstrate a technique for overcoming thermodynamic scaling limitations, highlight a self-assembling system that exhibits these properties, demonstrate the validity (and limitations) of our results, and provide guidelines for how future investigations may be done more rapidly. In so doing, it is our hope that we can provide support for the growing body of knowledge surrounding these problems, and for the communities that stand to gain from our ultimate success.

Keywords: Chemical Engineering.
Advisor: Nørskov Jens K.
Jaramillo Thomas Francisco advisor. Thesis advisor
Prinz F. B. advisor. Thesis advisor
Vojvodic Aleksandra