Type
Text
Type
Dissertation
Advisor
Li, Yan | Gersappe, Dilip | Orlov, Alexander | Halada, Gary | Wu, Qin.
Date
2015-05-01
Keywords
Materials Science
Department
Department of Materials Science and Engineering.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76281
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Nanoparticles (NPs) are useful in a wide variety of applications, such as sensors, catalysis, and biomedical materials. NPs often exhibit properties that are distinctively different from bulk materials, which are largely determined by their size, shape and surface modifications. Characterizing NP structures remains a challenge due to their small size, low symmetry, and the presence of defects and surface disorders, which often falls beyond the scope of experimental techniques. Work in this thesis focuses on characterizing bare and supported noble metal NPs towards a fundamental understanding of their structural, energetic and electronic properties, by a combined density function theory (DFT) and classical force field (FF) study. The first half of the thesis is devoted to the study of the size-, shape- and temperature dependence of unsupported noble metal NPs. A series of nm-sized Au NPs were investigated using classical FF simulations, and the performance was evaluated by DFT calculations for small clusters up to 249 atoms. The trend of cohesive energy and bond length distribution as a function of size were extracted and analyzed. Larger NPs (3nm-10nm) were studied using the classical FF simulations with the embedded atom method (EAM) potentials. In particular, simulated annealing was performed to systematically study the temperature effects on structural features of crystalline and amorphous NPs. The thermal behaviors of spherical and cubic NPs were characterized by coordination numbers, mean interatomic distances and radial distribution functions. In the second half of this thesis, we moved on study supported Pt clusters on semiconductor CdS surface by a comprehensive DFT study, which was motivated by the significantly enhanced photocatalytic activity of hydrogen production experimentally observed upon adsorption of Pt clusters on CdS. The trends of cohesive energy, bond length distribution, and excitation energy (e.g. ionization potential and electron affinity) as a function of size (10 atoms to 140 atoms) and shape (2D bilayer or 3D truncated octahedron) were extracted and analyzed for a series of sub-nm and nm-sized Pt NPs. The adsorption characteristics and interface electronic structure of a single Pt atom, a 2D Pt19 cluster, and a 3D Pt38 cluster on the nonpolar CdS(101b0) surface were investigated. Severe structural deformation in the supported cluster and the substrate were observed, accompanied by significant modifications of the surface electronic structure and shift in local surface potential. A comprehensive picture of the structural and electronic interactions at the metal NP-semiconductor interface was obtained towards better understanding of the role of supported NPs in photocatalytic reactions. | 106 pages
Recommended Citation
Xiong, Shangmin, "Characterization of Noble Metal Nanocatalysts from First-Principles Calculations and Classical Force Field Simulations" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2207.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2207