Liyuan Sun - Academia.edu (original) (raw)
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Papers by Liyuan Sun
Industrial & Engineering Chemistry Research, 2015
The journal of physical chemistry. B, 2015
We report experiments and simulations to understand the factors that control chromium (Cr(3+)) el... more We report experiments and simulations to understand the factors that control chromium (Cr(3+)) electrodeposition from ionic liquid solutions. Speciation, conductivities and diffusivities in mixtures of trivalent chromium chloride, water and choline chloride (CrCl3/xH2O/yChCl) were computed from molecular dynamics simulations and compared to measured ultraviolet-visible spectra, conductivities from electrical impedance spectroscopy, and cyclic voltammograms. Computed changes in Cr(3+) first solvation shell and conductivity with solution composition qualitatively agree with experimental observations. The Cr(3+) first solvation shell contains predominantly H2O and Cl(-) and the proportion of the two ligands changes with the relative bulk concentrations of each. Conductivities and diffusivities are observed to be functions of these composition variables. Variations in observed reduction current are primarily determined by dynamical properties and are less influenced by speciation.
Langmuir, 2014
The ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf 2 N]) o... more The ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf 2 N]) offers new ways to modulate the electrochemical reduction of carbon dioxide.
A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)-phosphonium cations ... more A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)-phosphonium cations paired with three different aprotic heterocyclic anions (AHAs) (alkyl = butyl ([P 2224 ] +) and octyl ([P 2228 ] +)) were prepared to investigate the effect of cationic alkyl chain length on transport properties. The transport properties and density of these ILs were measured from 283.15 to 343.15 K at ambient pressure. The dependence of the transport properties (viscosity, ionic conductivity, diffusivity, and molar conductivity) on temperature can be described by the Vogel−Fulcher−Tamman (VFT) equation. The ratio of the molar conductivity obtained from the molar concentration and ionic conductivity measurements to that calculated from self-diffusion coefficients (measured by pulsed gradient spin−echo nuclear magnetic resonance spectroscopy) using the Nernst−Einstein equation was used to quantify the ionicity of these ILs. The molar conductivity ratio decreases with increasing number of carbon atoms in the alkyl chain, indicating that the reduced Coulombic interactions resulting from lower density are more than balanced by the increased van der Waals interactions between the alkyl chains. The results of this study may provide insight into the design of ILs with enhanced dynamics that may be suitable as electrolytes in lithium ion batteries and other electrochemical applications.
Industrial & Engineering Chemistry Research, 2015
The journal of physical chemistry. B, 2015
We report experiments and simulations to understand the factors that control chromium (Cr(3+)) el... more We report experiments and simulations to understand the factors that control chromium (Cr(3+)) electrodeposition from ionic liquid solutions. Speciation, conductivities and diffusivities in mixtures of trivalent chromium chloride, water and choline chloride (CrCl3/xH2O/yChCl) were computed from molecular dynamics simulations and compared to measured ultraviolet-visible spectra, conductivities from electrical impedance spectroscopy, and cyclic voltammograms. Computed changes in Cr(3+) first solvation shell and conductivity with solution composition qualitatively agree with experimental observations. The Cr(3+) first solvation shell contains predominantly H2O and Cl(-) and the proportion of the two ligands changes with the relative bulk concentrations of each. Conductivities and diffusivities are observed to be functions of these composition variables. Variations in observed reduction current are primarily determined by dynamical properties and are less influenced by speciation.
Langmuir, 2014
The ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf 2 N]) o... more The ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf 2 N]) offers new ways to modulate the electrochemical reduction of carbon dioxide.
A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)-phosphonium cations ... more A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)-phosphonium cations paired with three different aprotic heterocyclic anions (AHAs) (alkyl = butyl ([P 2224 ] +) and octyl ([P 2228 ] +)) were prepared to investigate the effect of cationic alkyl chain length on transport properties. The transport properties and density of these ILs were measured from 283.15 to 343.15 K at ambient pressure. The dependence of the transport properties (viscosity, ionic conductivity, diffusivity, and molar conductivity) on temperature can be described by the Vogel−Fulcher−Tamman (VFT) equation. The ratio of the molar conductivity obtained from the molar concentration and ionic conductivity measurements to that calculated from self-diffusion coefficients (measured by pulsed gradient spin−echo nuclear magnetic resonance spectroscopy) using the Nernst−Einstein equation was used to quantify the ionicity of these ILs. The molar conductivity ratio decreases with increasing number of carbon atoms in the alkyl chain, indicating that the reduced Coulombic interactions resulting from lower density are more than balanced by the increased van der Waals interactions between the alkyl chains. The results of this study may provide insight into the design of ILs with enhanced dynamics that may be suitable as electrolytes in lithium ion batteries and other electrochemical applications.