Electron transport dynamics in room temperature redox molten salts and chemistry of monolayerprotected AU nanoparticles Public Deposited

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  • March 20, 2019
Creator
  • Wang, Wei
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Chapter One briefly introduces the basics of redox molten salts and monolayer-protected Au nanoparticles. Chapter Two examines the mass transport of counterions in molten salts of ruthenium complexes where the counterions are mixtures of perchlorate and iodide ions. The average diffusion coefficients of the counterions were obtained by ionic conductivity impedance measurements, while that of iodide (as a surrogate for perchlorate ion transport) was measured directly using iodide voltammetry. Agreement between the conductivity-based and Faradaic counter ion transport data provides a quantitative validation of previous use of ionic conductivity data in electron transfer dynamics study in redox semi-solids. Chapter Three focuses on the ligand-exchange reaction of phenylethanethiolate (SC2Ph) ligands on 1.1 nm Au nanoparticles with varied amounts of triphenylphosphine. The results from UV-Vis, NMR and electrochemistry suggest that the reaction liberate AuISC2Ph complexes (accompanying core size change), as opposed to SC2Ph thiols, the common out-coming ligands in thiolat-to-thiolate ligand exchange reaction on Au nanoparticles. Chapter Four explores a room-temperature Au38 nanoparticle polyether melt in which voltammetric and chronoamperometric, and impedance measurements have been made, respectively, of the rates of electron and ion transport in the melt. The measured rates of electron and of electrolyte ion transport are very similar, as are their thermal activation energy barriers, observations that are consistent with a recently introduced ionic atmosphere relaxation model for control of electron transfer in redox polyethers. Chapter Five describes ferrocenated imidazolium molten phases where ferrocene is chemically linked to various dialkylimidazoliums. The physical properties, including density, fluidity, and ionic characteristics, are discussed. The electrochemical results are presented in Chapter Six. It is observed that the electron diffusion in structurally-different ferrocenated imidazoliums is more efficient than the physical transport of redox ions. The rate of electron transfer is linearly correlated to the counterion diffusion, the first observation from imidazolium-based redox semi-solids consistent with the counterion relaxation control of electron transfer model. Chapter Seven investigates the surface properties of Au nanoparticle films contacted with imidazlium ionic liquids. A dynamic contact angle change is observed and explained on the basis of anion penetration which is further compared to the formally similar electrowetting phenomenon.
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  • Murray, Royce W.
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