Chemistry Commons^™

Hemithioindigo-Based Photoswitchable Self- Complementary Hydrogen Bond Arrays, Suendues Noori

Electronic Thesis and Dissertation Repository

Hydrogen bonded materials are slowly conquering grounds in the literature because of their dynamic features which stem from their reversible interactions. Incorporating the ability for light to chemically modify these interactions provides a unique template for innovative, efficient and self-healing materials. This thesis explores the design, synthesis, and characterization of nine derivatives of a well-known organic compound – hemithioindigo – with dual function; as a photoswitch and a novel self-complementary hydrogen bond array. The supramolecular complexes formed moderate to strong associations (63 M^-1 to 1100 M^-1) with spontaneous Gibbs free energy values (-10.3 kJ/mol to -17.3 kJ/mol) …

Electrochemiluminescence Of A Di-Boron Complex, Perovskite And Carbon Quantum Dots, Jonathan M. Wong

Electronic Thesis and Dissertation Repository

The electrochemiluminescence (ECL) of three novel materials was explored in this thesis. A di-boron complex exhibiting crystallization-induced blue shift emission was detected utilizing photoluminescence. This phenomenon was successfully observed in the annihilation pathway, resulting in crystallization-induced blue shift ECL. The effects of coreactant and crystallization-induced enhancements were distinguished utilizing two testing systems. Undoped and Mn-doped CsPbCl₃ perovskites were investigated, as the latter exhibits a dual emissive photoluminescence pathway due to host and dopant emission mechanics. It was discovered that the electrochemiluminescence of Mn-doped CsPbCl₃ proceeds through a triplet-triplet annihilation pathway. Furthermore, the relaxation of the electrochemically generated Mn-doped …

Fabricating Cu2znsns4, Cu2znsn(S,Se)4 And Cuin(S,Se)2 Light-Absorbing Thin Films For Low-Cost Solar Devices., Vaishnavi Raja

Electronic Thesis and Dissertation Repository

In this thesis, Cu₂ZnSnS₄ (CZTS), Cu₂ZnSn(S,Se)₄ (CZTSSe) and CuIn(S,Se)₂ (CISSe) thin-films have been optimized to use as the key light-absorbing and conversion layer for solar cells. CZTS nanocrystals (NCs) were solvothermally synthesized, etched with acetic acid and structurally analyzed using synchrotron spectroscopy. Electrodeposited CZTSSe films showed a non-ideal increase in sulfur with lower selenization temperature and post-process etching. Compositional studies of electrodeposited CISSe films confirmed the decrease in selenium after the acetic acid etching. Through PECMs and other conventional characterization techniques, it was determined that non-etched CZTSSe and CISSe solar devices performed better …

The Electrochemical And Corrosion Study Of Copper For Nuclear Waste Containers Under Deep Geological Disposal Conditions, Mengnan Guo

Electronic Thesis and Dissertation Repository

The proposed method for the safe disposal of Swedish, Finnish, and Canadian high-level nuclear waste (HLNW) is to isolate it in iron or steel containers with an outer copper (Cu) shell or coating and bury it in a deep geological repository (DGR). Copper has been selected as the corrosion barrier due to its stability in the aqueous anoxic environments anticipated in DGR conditions. The container will initially be exposed to humid aerated conditions which will evolve to cool and anoxic as radiation fields in the fuel decay and heat production ceases. When the DGR is cool and anoxic, sulphide (SH …

Hybrid Density Functionals With Proper Exact Exchange, Liyuan Ye

Electronic Thesis and Dissertation Repository

Hybrid density functionals have the best overall performance among standard density func-tional approximations (DFA). According to their original design, hybrid DFAs are supposedto use the exact exchange (EXX). However, when hybrid functionals were originally intro-duced, there was no simple method to compute EXX, so all of their practical implementationsstarted using the Hartree–Fock exchange (HFX), which can be computed easily and is simi-lar to but distinct from EXX. Recent development of an efficient method for computing EXXmade it possible to implement hybrid functionals in line with their original definition. Weimplemented EXX in the PBE0 functional and compared its performance with that …

Theoretical Investigation Of Pressure-Induced Structural Transformations Of Ethylenediamine Bisborane, Rongfeng Guan

Electronic Thesis and Dissertation Repository

High-pressure experiments on hydrogen-rich compounds provide crucial data for the rational design of hydrogen storage materials. Ethylenediamine bisborane (EDAB), BH₃·NH₂CH₂CH₂NH₂·BH₃, is one of the prime candidates for this role due to its high hydrogen content (10 wt%) and good kinetic stability under ambient conditions. Previous studies of EDAB using in situ Fourier-transform infrared (IR) spectroscopy, Raman spectroscopy, and synchrotron X-ray diffraction (XRD) techniques suggested that EDAB undergoes two possible phase transitions in the pressure range of 0 to 17 GPa. However, the crystal structures of the two new …

Electronic And Local Structures Of Pt-Based Bimetallic Alloy And Core-Shell Systems, Jiatang Chen

Electronic Thesis and Dissertation Repository

This thesis investigates the electronic structure of Pt for catalysis applications. The importance of the Pt 5d band is discussed in terms of the bonding capability of Pt. The oxygen reduction reaction in proton exchange membrane fuel cells is chosen as the catalytic reaction model to illustrate the effect of Pt 5d states on Pt-O interaction. Pt-based bimetallic systems are introduced as a solution for the high price and limited resources of Pt. Despite lower usage of Pt, the tuning capability to optimize the Pt 5d band in bimetallic catalysts is supposed to provide superior catalytic activity. Advanced synchrotron X-ray …

Galvanic Corrosion Of Carbon Steel-Stainless Steel Welds, Mi Li

Electronic Thesis and Dissertation Repository

A water leak in one of the Canada Deuterium Uranium (CANDU) nuclear reactors could lead to galvanic corrosion between the materials of its supporting structures: carbon steel (CS) and stainless steel (SS). This project investigates the effects of physical and chemical solution parameters on the corrosion of galvanically coupled dissimilar CS-SS welds, with the aim of developing a corrosion dynamics model that can be used to assess the long-term integrity of the CANDU reactor structural materials with confidence. The studied parameters were solution pH, temperature, the presence or absence of γ-radiation and the cathode:anode surface area ratio. Multiple electrochemical techniques …

Gamma-Radiolysis Kinetics And Its Role In The Overall Dynamics Of Materials Degradation, Ryan P. Morco

Electronic Thesis and Dissertation Repository

The γ-radiation emitted during radioactive decay of the wastes in a nuclear fuel container can affect container corrosion. When a metal/water system is exposed to γ-radiation both the solid metal and the liquid water (or humid air) absorb energy. This energy dissipates mainly as heat in the metal but induces decomposition of water molecules to yield a range of chemically reactive species. The different chemical environments induced in the metal and liquid phases can change the driving forces for surface reactions and thereby influence the rate and pathway of metal corrosion.

This thesis presents the development of radiolysis kinetic models …

Nonlinear Dynamics Of Carbon Steel Corrosion Under Gamma Radiation, Youn Gyeong Shin

Electronic Thesis and Dissertation Repository

Corrosion of materials is still an unresolved problem affecting a multitude of industries. One of the grand challenges facing the corrosion community is the development of high-fidelity models for corrosion in actual service environments. The difficulties arise since corrosion involves transfer of metal atoms between the solid and solution phases thus making the system non-adiabatic. Interfacial transfer of atoms increases the chance of establishing systemic feedback between chemical reactions and transport processes, which results in chemical oscillation and periodic patterns on the corroding surfaces. These oscillating behavior in electrochemical measurements and pattern formation on corroding surfaces have been reported in …

Plasmon-Enabled Physical And Chemical Transformations Of Nanomaterials, Danielle Mcrae

Electronic Thesis and Dissertation Repository

When the electromagnetic field of light is incident on metallic nanostructures of dimensions smaller than the incident wavelength of the light, there is a strong interaction, resulting in an enhanced, highly confined electromagnetic field in the vicinity of the nanostructure. This effect is referred to as a localized surface plasmon resonance, most commonly exploited for plasmon-enhanced spectroscopies, such as surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS). The location, number and intensity of these regions of enhancement, or “hotspots”, can be tuned by changing the nature of the metal, the size, shape and arrangement of the nanoparticles, its surroundings, …