UCLA

The urgent global need for sustainable solutions has propelled the search for efficient catalytic systems. This thesis focuses on key reactions crucial for achieving a greener and more sustainable future. Employing computational techniques and theoretical models, the research investigates catalytic processes to unravel fundamental principles, guiding the design of advanced catalysts. The thesis leads to a comprehensive exploration of the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), partial oxidation of methane to methanol, and CO2 hydrogenation. By elucidating the structure, stability, and catalytic reactivity of diverse clusters and surfaces, the research aims to develop efficient and sustainable catalytic systems.Emphasizing accurate characterization of active site composition and understanding catalyst behavior under reaction conditions, the thesis employs first-principles density functional theory (DFT) calculations to determine optimal doping sites and structures for Sn atoms on the ii Sn-doped Indium Oxide (ITO) surface. The interaction between the ITO surface and Pt clusters is also explored, providing insights into the role of active sites in catalytic reactivity. Investigating small Pt clusters supported on ITO in HER, a size-dependent activity trend is uncovered, highlighting the catalytic potential of Pt hydride compounds. The inclusion of metastable isomers in microkinetic models emphasizes the significance of considering accessible isomer ensembles for accurate simulations of sub-nano supported cluster catalysts. Furthermore, the thesis unravels the intricate mechanism of OER, identifying the rate-determining step and changes in the oxidation state of Pt surface atoms (Pt-SA) during the catalytic cycle. Understanding electron transfer contributions from both Pt-SA and the ITO surface provides valuable insights for designing efficient OER catalysts. In the context of partial oxidation of methane to methanol, the research explores electrochemical methods for catalyst deposition, focusing on thin-film transition metal (oxy)hydroxides. The activity and selectivity of various catalysts are investigated, emphasizing control over kinetics and mass transfer for sustainable methanol production. Finally, the thesis investigates CO2 hydrogenation, a promising avenue for converting carbon dioxide into valuable chemicals. Analyzing the Zr3OxOHy (HCOO)z/Cu111 cluster under different reaction conditions, the research unveils the pivotal role of hydroxyls and HCOOs in shaping the reaction mechanism. Electronic insights guide the design of catalysts with optimal properties, potentially enhancing catalytic performance. By integrating computational modeling and experimental characterization techniques, this research enhances our understanding of critical catalytic reactions. The findings underscore the importance of active site composition, surface structures, and electronic properties in determining catalytic reactivity. The synergy between theory and experiment holds promising prospects for designing advanced catalysts with improved activity, selectivity, and stability.