Metal Oxide-Mediated Transformations of Small Molecules for Chemical Synthesis and Energy Storage
To date, the ever-increasing global demands for energy and chemicals have been met primarily by utilizing fossil fuel resources. With the increase consumption of fossil resources, major concerns have been raised in terms of its detrimental impacts on the climate and public health. Accordingly, development of sustainable technologies are crucial to relieve the heavy dependence on fossil fuels and mitigate its adverse effects. This thesis focuses on such sustainable technologies involving electrochemical transformations of small molecules (e.g., O2 and H2O) for the production of H2, a storable chemical fuel, and H2O2, a valuable chemical oxidant. Using a combination of experimental and computational approaches, metal oxide electrocatalysts are investigated. In the first section (chapter 3), the effects of the synthetic route on the oxygen evolution reaction (OER) performance are explored using amorphous RuOx electrocatalysts; a benchmark catalyst for acidic OER. Structural, electrochemical, and spectroscopic analyses revealed a significant impact in performance by the deposition method, whereas the precursor used in the preparation of the catalyst had little influence. In the second section (chapter 4), the effects of heteroatom doping on the catalytic activity were explored via density functional theory. TiO2, a cost-effective, durable catalyst was doped with various amounts of Mn. DFT calculations showed optimal binding of reaction intermediates on the surface of the Mn-doped TiO2. As a result, the OER catalytic onset potential was decreased. The enhanced OER performance was corroborated by experimental studies, wherein a 370 mV reduction in onset potential was achieved through optimal amounts of Mn doping. Lastly, bifunctional catalysts to promote H2O2 production via the anodic two-electron water oxidation (2e-WOR) and cathodic two-electron oxygen reduction reaction (2e-ORR) were studied in the third section (chapter 5). Using DFT calculations, the catalytic activity, selectivity, and stability of SnO2-supported single atom catalysts were assessed. W:SnO2 was identified as a promising candidate for the 2e-ORR, while Ti:SnO2, Fe:SnO2, and Mn:SnO2 for the 2e-WOR. This thesis is another step in the collective effort to transition away from fossil fuels and creating economically-attractive, sustainable technologies for the future of clean energy and chemical production.
Electrocatalysis, Metal oxide, Density functional theory, Amorphous materials, Oxygen reduction reaction, Water electrolysis, Thin film deposition
Jimenez Villegas, S. (2022). Metal oxide-mediated transformations of small molecules for chemical synthesis and energy storage (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.