Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 14 of 14 for “"in situ NMR"”.
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NMR Studies of Solid-Supercritical Fluid Mixtures and a New Technique for NMR Diffusion Measurements
Solid solubilities of naphthalene in supercritical carbon dioxide have been measured near the upper critical end point of the binary mixture by using a novel, in situ NMR technique. The pressure-temperature trace of the solid-liquid-gas phase line that terminates at the upper critical end point was …
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Nuclear Magnetic Resonance Studies of Lithium Metal Anodes
Lithium metal has received a renewed interest as a promising anode material for next-generation, high-energy batteries owing to its high specific capacity (3860 mAh g-1) and low reduction potential (-3.04 V vs. the standard hydrogen electrode). However, lithium metal batteries suffer from low …
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Spectroscopic and synthetic studies relating to a dirhodium hydroformylation catalyst
The main goal of this dissertation research was to further study and characterize our bimetallic hydroformylation catalyst, rac-[Rh<sub>2</sub>(nbd)<sub>2</sub>(et,ph-P4)](BF<sub>4</sub>)<sub>2</sub>, and to fully identify the catalytically inactive mono- and dirhodium complexes formed upon …
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Synthesis and reactivity of α-diazosulfoxides and α-diazosulfones
… have been synthesised by the Maguire-Collins research group since the mid-1990s using a Regitz diazo transfer method. In this work in situ NMR monitoring has been used to gain a deeper understanding of the relative reactivity of diastereomeric sulfoxides in this reaction. α-Diazosulfoxides …
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Chemistry and synthesis of 3(2H)-furanones and 4,5-dihydro analogues: mechanistic investigations and stereochemical control
… their synthesis and key transformations. In chapter two, new research on 3(2H)-furanones is outlined in two parts. The first describes an investigation into the cyclisation of α'-trialkylsilyloxyenone adducts with arenesulfenyl and selenenyl chlorides into the corresponding sulfur and …
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New Directions in Metal Chalcogenide Nanochemistry
… nanocrystals have shown great promise in functional devices such as solar cells and LEDs, but still relatively little is understood about the chemistry of their formation and resulting structure. In this thesis, we describe the results of our study of ultrathin Bi2S3 nanowires, part of …
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Towards a Fundamental Understanding of Aqueous Organic Redox Flow Batteries – A Study of Degradation, Aggregation, and Reactivity
Renewable energy sources such as wind, solar, and hydropower are becoming more prominent in the global energy mix. To address intermittency and ensure a reliable energy supply, grid-scale energy storage systems are crucial. Redox flow batteries (RFBs) are a useful tool for grid-scale energy storage …
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Tracking the Function and Failure of Li-Air Electrolytes using Electrochemical and Spectroscopic Methods
Li-air batteries (LABs) have gained significant attention due to their high gravimetric energy densities that are comparable to fossil fuels, with the added advantage of being greener than Lithium ion batteries, as they contain no transition metals. LABs rely on the reaction with O2 and the …
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Nuclear Magnetic Resonance Studies of Ion Adsorption in Supercapacitor Electrodes
… by the non-faradaic adsorption of ions at the interface between porous carbon electrodes and an electrolyte solution. The development of new electrode materials and electrolytes with improved performances is an active area of research today, yet there are relatively few studies of the molecular …
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In-situ 13C CM-MAS NMR study of dilute acid biomass pretreatment on 13C enriched poplar wood
In situ 13C NMR measurements are reported on 13C-enriched powdered poplar wood that is subjected to pretreatment with water and 0.5 M sulfuric acid as a function of time at 150 °C. 13C MAS (magic-angle spinning) spectra were obtained in both the CP (cross polarization) and DP (direct polarization) …
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NANOSTRUCTURED MATERIALS FOR ALKALIS ION BATTERIES AND THEIR MECHANISTIC STUDIES
To be comparable with combustion engine and practical for large-scale applications in smart grids, the energy density and the rate capability of LIBs and SIBs must be improved, which urges the exploitation of novel composite cathode or anode materials high specific capacity, high rate capability, …
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NMR and neutron total scattering studies of silicon-based anode materials for lithium-ion batteries
Silicon (in the form of lithium silicides) has almost ten times the theoretical charge storage capacity of graphite, the anode material used in most commercially-available lithium-ion batteries. Replacing graphite with silicon therefore promises a substantial improvement over the state-of-the-art …
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Deformation induced molecular behavior of Cis 1,4-polyisoprene and its nanocomposites monitored by solid-state NMR
Proton spin lattice (T1) relaxation time constants were used to monitor changes in the molecular motion and architecture of polyisoprene, polyisoprene-clay composites and polyhedral oligomeric silsesquioxane (POSS) nanofillers. The high frequency relaxations monitored by NMR are sensitivity to …
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Metal-ligand cooperativity in first row transition metals: hydrosilylation catalysis and mechanistic insights
… Historically, homogenous catalysis is dominated by platinum group metals (PGMs) due to their relative high activity and stability to air when compared to the 1st row counterparts of PGMs. However, 1st row late transition metals such as Fe, Co, and Ni offer the advantage of being low cost …