Atomic-Scale Insights into the Surface Structure and Reactivity of Model Catalytic Surfaces: Towards the Design of Sustainable Catalysts
Patel, Dipna.
2021
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Thesis (Ph.D.)--Tufts University, 2021.
Submitted to the Dept. of Chemistry.
Advisor: E Charles Sykes.
Committee: Arthur Utz, Yu-Shan Lin, and Michael Trenary.
Keywords: Physical chemistry, and Chemistry.
Heterogeneous catalysis is at the heart of many industrial processes and is responsible for the production of goods exceeding trillions of dollars in ... read morevalue. Heterogeneous catalytic processes are complex and require optimization in terms of catalyst design and reaction parameters to achieve high activity while maintaining selectivity towards desired products. Many catalytic processes utilize Pt, Pd, and Rh which are costly precious metals with low natural abundance. These catalysts are susceptible to low selectivity which can lead to catalyst deactivation. Optimization and design of both existing and novel sustainable catalysts requires an integrated approach where theory driven design of model catalysts can be used to gain atomic-scale insight into the surface structure and fundamental chemistry. The work presented in this dissertation uses a surface science approach to design and investigate the surface structure, elementary reaction steps, and molecular adsorption on model catalytic surfaces towards sustainable catalysis. A majority of the work focuses on investigating ensemble effects of dopant atoms such as Ni, Pt, and Pd in and on Cu- and Ag-based alloys for hydrogen activation, CO adsorption, and ethanol dehydrogenation. By optimizing the configuration of the dopant metal to a single atom, highly active and CO-tolerant single-atom alloy catalysts can be designed. While a small critical ensemble is required for hydrogen activation, as shown in the case for PdAg, theory driven design of PtAg and NiCu single-atom alloys demonstrate reduced susceptibility to CO poisoning while offering mechanistic insights into dehydrogenation activity. By utilizing a model surface science approach, atomic-scale insight into the surface structure of bimetallic surfaces highlights an opportunity to investigate well-defined Cu- and Ag-based dilute and single-atom alloy model systems for selective hydrogenation and dehydrogenation reactions. On monometallic surfaces, investigation of molecule-substrate and molecule-molecule-substrate interactions is key to understanding fundamental chemistry of the oxidation of alcohols on Au. Atomic-scale resolution on monometallic model surfaces allows for the investigation of molecular adsorption of reactants and intermediates in order to correlate surface structure with observed reactivity.read less - ID:
- ft849443n
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