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Articles 6541 - 6570 of 33172

Full-Text Articles in Chemistry

Investigating The Proton Transfer Dynamics And Vibrational Spectrum Of Hydrogen Oxalate Using Driven Molecular Dynamics Simulations, Martina Kaledin, Dominick Pierre-Jacques, Olivia Cochran, Dayana Salazar, Dalton Boutwell, Martina Kaledin Aug 2021

Investigating The Proton Transfer Dynamics And Vibrational Spectrum Of Hydrogen Oxalate Using Driven Molecular Dynamics Simulations, Martina Kaledin, Dominick Pierre-Jacques, Olivia Cochran, Dayana Salazar, Dalton Boutwell, Martina Kaledin

Symposium of Student Scholars

In this computational chemistry work, we describe ab initio calculations and assignment of infrared (IR) spectra of an intramolecular H-bonding system hydrogen oxalate, C2O4H–. The mechanism and dynamics of proton transfer are of fundamental importance in chemistry and biology. In C2O4H–, proton transfer occurs along the non-linear path. Previous experimental studies are signaling very strong coupling between OH stretch mode and low frequency motions. We calculated IR spectra at 300 K using the direct molecular dynamics (MD) method at the MP2/ aug-cc-pVDZ level of theory and assigned the …

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Molecular Vibrations Of Symmetric Molecules: Raman Scattering Driven Molecular Dynamics Method, Martina Kaledin, Dominick Pierre-Jacques, Ciara Tyler, Jason Dyke Aug 2021

Molecular Vibrations Of Symmetric Molecules: Raman Scattering Driven Molecular Dynamics Method, Martina Kaledin, Dominick Pierre-Jacques, Ciara Tyler, Jason Dyke

Symposium of Student Scholars

This project focuses on developing a novel computational technique to study molecular vibrations through infrared (IR) and Raman scattering Driven Molecular Dynamics (DMD) method. While the main criterion for IR absorption is a net change in the dipole moment in a molecule as it vibrates, presently we wish to predict and analyze vibrational spectra to study symmetric vibrational modes that are IR inactive or weakly active while strongly Raman active. A newly developed method was tested on CO2, H2O, CH4, and C20 molecules. Students optimized the molecular structures, obtained vibrational frequencies, and IR …

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Investigating Cathode Dissolution By Homogenous Sol-Gel Coating On Manganese Dioxide Nanofibers To Extend Battery Performance, Milan Haddad Aug 2021

Investigating Cathode Dissolution By Homogenous Sol-Gel Coating On Manganese Dioxide Nanofibers To Extend Battery Performance, Milan Haddad

Symposium of Student Scholars

The cathode dissolution is a known phenomenon for manganese dioxide (MnO2) based cathode materials in both aqueous and non-aqueous batteries. Upon battery discharge, reduced Mn3+ species disproportionate (2Mn3+→ Mn4+ + Mn2+) and Mn2+ dissolves into the electrolyte causing the loss of active material. While MnO2 is a promising cathode for rechargeable aqueous zinc ion batteries (ZIB) due to its availability and low toxicity, the electrochemical performance is limited during battery cycling due to the dissolution of the cathode. In this work, a homogeneous sol-gel SiO2 coatings with various thicknesses …

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Probing Structure And Energetics Of Proton-Bound Complexes N2…Hco+ And N2h+…Oc Using Computational Chemistry Methods, Antonio Barrios, Dalton Boutwell, Onyi Okere, Monique Olocha, Oluwaseun Omodemi, Alexander Toledo, Antonio Barrios Aug 2021

Probing Structure And Energetics Of Proton-Bound Complexes N2…Hco+ And N2h+…Oc Using Computational Chemistry Methods, Antonio Barrios, Dalton Boutwell, Onyi Okere, Monique Olocha, Oluwaseun Omodemi, Alexander Toledo, Antonio Barrios

Symposium of Student Scholars

N2…HCO+ and N2H+…OC are predicted to exist in interstellar clouds. These complexes involve HCO+ and N2H+ fragments that are bound to N2 and CO, respectively using hydrogen-bonded interaction. The reason these molecules are important is that the existence of nitrogen can be measured indirectly through ion-molecular complexes studied in this work. The measured vibrational spectra of molecules is an excellent way to characterize and detect molecules. We used B3LYP, MP2, and CCSD(T) computational methods to predict the structure and vibrational frequencies of N2…HCO+ and N …

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Theoretical Study On The Isomerization And Detection Of N2h+…Oc Complex In Interstellar Clouds, Dalton Boutwell, Martina Kaledin Aug 2021

Theoretical Study On The Isomerization And Detection Of N2h+…Oc Complex In Interstellar Clouds, Dalton Boutwell, Martina Kaledin

Symposium of Student Scholars

In this study, we characterize N2H+…OC linear complex using Driven Molecular Dynamics (DMD) and Vibrational Self-Consistent Field Theory (VSCF) methods due to its relevance in astrochemistry. A central challenge is the detection of the molecular complex in interstellar media (ISM). Computational chemistry approaches can predict vibrational spectra, hence facilitate prediction of its existence and stability in the ISM. N2H+…OC involves the proton transfer process via hydrogen bonding interaction. Proton motion is highly anharmonic, therefore facing a significant challenge to characterize it accurately. Quantum mechanical variational methods are popular among many theoretical chemists …

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Activated Carbon Pore Expansion Using Acidic Hydrothermal Method, Max Thompson Aug 2021

Activated Carbon Pore Expansion Using Acidic Hydrothermal Method, Max Thompson

Symposium of Student Scholars

Petroleum Coke is a widely abundant, high carbon content material produced as a byproduct of the oil refining process. Its abundance makes the price per ton low and it is produced in almost all regions of the world. Due to the low price and high carbon percentage, commercial companies make large amounts of activated carbon using petroleum coke as a precursor. These activated carbons are characterized by their high surface area and can achieve widely varying pore morphology with different activation processes. The goal of this work is to achieve a homologous mesopore activated carbon material for use in super …

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Solid-State Redox Synthesis Of Layered Birnessite-Type Manganese Dioxide (Δ-Mno2) As Aqueous Supercapacitor Electrodes, Armando Rodriguez Campos Aug 2021

Solid-State Redox Synthesis Of Layered Birnessite-Type Manganese Dioxide (Δ-Mno2) As Aqueous Supercapacitor Electrodes, Armando Rodriguez Campos

Symposium of Student Scholars

Nanostructured manganese dioxides are attractive cathode materials in aqueous supercapacitors due to their low cost, environmental benign nature, high theoretical gravimetric capacitance, and power in neutral aqueous electrolytes. In this work, a layered birnessite-type manganese dioxide (δ-MnO2) is synthesized utilizing solid-state redox method with superoxide. The effects of temperature and oxidant amount on the physicochemical properties of δ-MnO2 are characterized using Elemental Dispersion X-ray (EDX) spectroscopy, X-ray diffraction (XRD), N2-sorption, and Scanning Electron Microscope (SEM). The physiochemical properties that are specifically analyzed by varying synthesis conditions pertain to the chemical composition, morphology, and surface area …

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Sources And Aftermaths Of Pipeline Related Leaks And Spills, Justin Smith Aug 2021

Sources And Aftermaths Of Pipeline Related Leaks And Spills, Justin Smith

Symposium of Student Scholars

The escape of oil and other hazardous materials have been shown to pollute and destroy ecosystems. As an aspiring chemist, I am adamant about the secure handling and transportation of oil and other hazardous materials. In the past, researchers have concentrated on oil’s high viscosity. Oil’s high viscosity physically smothers wildlife, affecting their ability to continue critical functions such as respiration, feeding, and thermoregulation. My research focuses on the source of these oil spills, as well as natural gas leaks, for the purpose of risk assessment. In addition, I compare recovery efforts based on the cause of the leak/spill, the …

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Elucidation Of The Combination Bands And Anharmonic Features In The Vibrational Spectra Of C2o4h- And C2o4d- With Driven Classical Trajectories, Dalton Boutwell, Martina Kaledin Aug 2021

Elucidation Of The Combination Bands And Anharmonic Features In The Vibrational Spectra Of C2o4h- And C2o4d- With Driven Classical Trajectories, Dalton Boutwell, Martina Kaledin

Symposium of Student Scholars

Hydrogen bonds are strong electrostatic interactions characterized by the anharmonic shift of vibrational modes of atoms involved with this intramolecular force. The low energy barrier of the H+ transfer in hydrogen oxalate (C2O4H-), predicted to be ~2.98 kcal/mol at the MP2/aVDZ level of theory, allows for rapid proton exchange in the system and confounds the experimental vibrational spectrum of the molecule with broad spectral features in the O-H stretching region. The molecule is planar and exhibits several torsional motions among some of its lower frequency fundamental vibrational transitions. Because H-bonding and torsional motions …

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Model Calculations Of H/D Isotope Substitution In Hydrogen Oxalate Anion Using The Normal Mode Analysis, Dominick Pierre-Jacques, Olivia Cochran, Dayana Salazar, Martina Kaledin Aug 2021

Model Calculations Of H/D Isotope Substitution In Hydrogen Oxalate Anion Using The Normal Mode Analysis, Dominick Pierre-Jacques, Olivia Cochran, Dayana Salazar, Martina Kaledin

Symposium of Student Scholars

In this computational chemistry work, we describe ab initio calculations and assignment of infrared (IR) spectra of an intramolecular H-bonding system hydrogen oxalate, C2O4H–. The study of H/D isotope effects can provide useful information on a proton’s location inside a non-linear pathway. In C2O4H–, a normal mode analysis was performed at the MP2/aug-cc-pVDZ and B3LYP/aug-cc-pVDZ levels of theory. Previous experimental studies suggest a frequency shift ~1000 cm-1 for the OH stretch mode upon the H/D isotopic substitution. Isotope calculations resulted in a shift of 842 cm-1 …

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Aqueous Photochemistry Of 2-Oxocarboxylic Acids: Evidence, Mechanisms, And Atmospheric Impact, Marcelo I. Guzman, Alexis J. Eugene Aug 2021

Aqueous Photochemistry Of 2-Oxocarboxylic Acids: Evidence, Mechanisms, And Atmospheric Impact, Marcelo I. Guzman, Alexis J. Eugene

Chemistry Faculty Publications

Atmospheric organic aerosols play a major role in climate, demanding a better understanding of their formation mechanisms by contributing multiphase chemical reactions with the participation of water. The sunlight driven aqueous photochemistry of small 2-oxocarboxylic acids is a potential major source of organic aerosol, which prompted the investigations into the mechanisms of glyoxylic acid and pyruvic acid photochemistry reviewed here. While 2-oxocarboxylic acids can be contained or directly created in the particles, the majorities of these abundant and available molecules are in the gas phase and must first undergo the surface uptake process to react in, and on the surface, …

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Synthesis Of 1-(2,4-Dinitrophenyl)-3,5-Diphenyl-1h-Pyrazol-4-Ol Via Trans-1,3-Diphenyl-2,3-Epoxy-1-Propanone, Oluwaseyi B Ovonramwen Aug 2021

Synthesis Of 1-(2,4-Dinitrophenyl)-3,5-Diphenyl-1h-Pyrazol-4-Ol Via Trans-1,3-Diphenyl-2,3-Epoxy-1-Propanone, Oluwaseyi B Ovonramwen

Tanzania Journal of Science

The trans-1,3-diphenyl-2,3-epoxy-1-propanone was synthesized from benzaldehyde and 2-bromoacetophenone in 20 min which is more economical. The presence of ethanol and Br in 2-bromoacetophenone facilitated the reaction. The vicinal diaxial coupling constant of trans-1,3-diphenyl-2,3-epoxy-1-propanone was zero, an indication of trans configuration for a rigid 3-membered ring at ~90o dihedral angle. 1-(2,4-Dinitrophenyl)-3,5-diphenyl-1H-pyrazol-4-ol was synthesized from trans-1,3-diphenyl-2,3-epoxy-1-propanone and 2,4-dinitro phenylhydrazine in glacial CH3COOH to give 85.5% yield and characterized using FTIR, 1H, 13C NMR, DEPT 135 and MS spectra. The 1-(2,4-dinitrophenyl)-3,5-diphenyl-1H-pyrazol-4-ol can be exploited for unique biological activities and in the synthesis of synthetic fibers. Keywords:    1-(2,4-dinitrophenyl)-3,5-diphenyl-1H-pyrazol-4-ol, trans-1,3-diphenyl-2,3-epoxy-1-propanone, synthesis, 2,4-dinitro phenylhydrazine.

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Physicochemical And Bacteriological Water Quality Parameters In Relation To Land-Use Practices At A Rural Catchment, Mbinga District, Tanzania, Harieth Hellar-Kihampa, Patrick Isdory Ndunguru Aug 2021

Physicochemical And Bacteriological Water Quality Parameters In Relation To Land-Use Practices At A Rural Catchment, Mbinga District, Tanzania, Harieth Hellar-Kihampa, Patrick Isdory Ndunguru

Tanzania Journal of Science

Data on physicochemical water quality parameters and contamination levels is crucial for protection and sustainable utilization of water resources. This study assessed the physicochemical water quality parameters, faecal coliform bacteria and nutrient loads in water at a catchment used for municipal supply in Mbinga District, Tanzania. Samples were seasonally collected from three areas characterized by distinct geographical features, settlement patterns and land-use practices, and analyzed using standard analytical protocols. Data were subjected to paired-sampled t-test and cluster analysis. The parameters varied as follows: pH (4.75–6.83); temperature (16.4–26.2 ºC); electrical conductivity (14.6–121.1 µS/cm); total dissolved solids (7.0–23.2 mg/L); total suspended solids …

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Unintended Consequences Of Air Cleaning Chemistry, Douglas B. Collins, Delphine K. Farmer Aug 2021

Unintended Consequences Of Air Cleaning Chemistry, Douglas B. Collins, Delphine K. Farmer

Faculty Journal Articles

Amplified interest in maintaining clean indoor air associated with the airborne transmission risks of SARS-CoV-2 have led to an expansion in the market for commercially available air cleaning systems. While the optimal way to mitigate indoor air pollutants or contaminants is to control (remove) the source, air cleaners are a tool for use when absolute source control is not possible. Interventions for indoor air quality management include physical removal of pollutants through ventilation or collection on filters and sorbent materials, along with chemically reactive processes that transform pollutants or seek to deactivate biological entities. This perspective intends to highlight the …

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Silk-Cellulose Acetate Biocomposite Materials Regenerated From Ionic Liquid, Ashley Rivera-Galetti, Chrtstopher R. Gough, Farhan Kaleem, Michael Burch, Chris Ratcliffe, Ping Lu, David Salas-De La Cruz, Xiao Hu Aug 2021

Silk-Cellulose Acetate Biocomposite Materials Regenerated From Ionic Liquid, Ashley Rivera-Galetti, Chrtstopher R. Gough, Farhan Kaleem, Michael Burch, Chris Ratcliffe, Ping Lu, David Salas-De La Cruz, Xiao Hu

College of Science & Mathematics Departmental Research

The novel use of ionic liquid as a solvent for biodegradable and natural organic biomaterials has increasingly sparked interest in the biomedical field. As compared to more volatile traditional solvents that rapidly degrade the protein molecular weight, the capability of polysaccharides and proteins to dissolve seamlessly in ionic liquid and form fine and tunable biomaterials after regeneration is the key interest of this study. Here, a blended system consisting of Bombyx Mori silk fibroin protein and a cellulose derivative, cellulose acetate (CA), in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc) was regenerated and underwent characterization to understand the structure and physical …

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Dft Study Of NiM@Pt1AuN-M-1 (N=19, 38, 55, 79; M = 1, 6, 13, 19) Core-Shell Orr Catalyst, Wen-Jie Li, Dong-Xu Tian, Hong Du, Xi-Qiang Yan Aug 2021

Dft Study Of NiM@Pt1AuN-M-1 (N=19, 38, 55, 79; M = 1, 6, 13, 19) Core-Shell Orr Catalyst, Wen-Jie Li, Dong-Xu Tian, Hong Du, Xi-Qiang Yan

Journal of Electrochemistry

The slow kinetics of oxygen reduction reaction (ORR) limits the performance of low temperature fuel cells. Thus, it needs to design effective catalysts with low cost. Core-shell clusters (CSNCs) show promising activity because of their size-dependent geometric and electronic effects. The ORR activity trend of Nim@Pt1Aun-m-1(n = 19, 38, 55, 79; m = 1, 6, 13, 19) was studied using the GGA-PBE-PAW methods. The adsorption configurations of *O, *OH and *OOH were optimized and the reaction free energies of four proton electron (H+ + e-) transfer steps …

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One-Pot Synthesis Of Fe2O3@Fe-N-C Oxygen Reduction Electrocatalyst And Its Performance For Zinc-Air Battery, Hua Lin, Yi-Jin Wu, Jun-Tao Li, Yao Zhou Aug 2021

One-Pot Synthesis Of Fe2O3@Fe-N-C Oxygen Reduction Electrocatalyst And Its Performance For Zinc-Air Battery, Hua Lin, Yi-Jin Wu, Jun-Tao Li, Yao Zhou

Journal of Electrochemistry

Oxygen reduction reaction (ORR) plays a profound role in determining cathode performance in metal-air batteries and fuel cells. Owing to its inherently sluggish kinetics, high-performance ORR catalysts which favors the scissoring of O-O bond and formation of O-H bond are a requisite. In this regard, Pt has been explored as the most efficient ORR electrocatalysts. Nevertheless, due to its expensiveness, the usage of Pt catalysts represents one of the major sources of cost in those energy conversion devices. Thus, the development of alternative ORR electrocatalysts with minimized Pt utilization has been widely pursued over the past few decades. Metal-nitrogen-carbon catalysts …

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Study On Mxene-Carbon Black/Sulfur Composite In Integrated Electrode Of Lithium-Sulfur Batteries, Ye-Peng Fan, Ye-Qiang Luo, Pei-Kang Shen Aug 2021

Study On Mxene-Carbon Black/Sulfur Composite In Integrated Electrode Of Lithium-Sulfur Batteries, Ye-Peng Fan, Ye-Qiang Luo, Pei-Kang Shen

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries are considered as a promising energy storage device due to their ultrahigh theoretical energy density of 2500 Wh·kg-1 and low cost. However, the practical application of Li-S batteries is seriously limited by their low actual energy density, the shuttle effect of polysulfides (LiPSs), and the insulating nature of sulfur and lithium sulfides. Carbon materials have been developed in the design of sulfur hosts due to their adjustable pore structure and high electrical conductivity, but their non-polar surfaces have weak interactions with LiPSs. Herein, MXene-carbon black/sulfur (Ti3C2Tx-CB/S) composites were prepared and …

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Preparation And Electrochemical Evaluation Of Mos2/Graphene Quantum Dots As A Catalyst For Hydrogen Evolution In Microbial Electrolysis Cell, Hong-Yan Dai, Hui-Min Yang, Xian Liu, Xiu-Li Song, Zhen-Hai Liang Aug 2021

Preparation And Electrochemical Evaluation Of Mos2/Graphene Quantum Dots As A Catalyst For Hydrogen Evolution In Microbial Electrolysis Cell, Hong-Yan Dai, Hui-Min Yang, Xian Liu, Xiu-Li Song, Zhen-Hai Liang

Journal of Electrochemistry

Microbial electrolysis cell (MEC) is a relatively new bioelectrochemical technology that produces H2 and meanwhile treats organic wastewater. Cathode hydrogen evolution catalyst plays a key role in MEC. The doping of Graphene Quantum Dots (GQDs) into MoS2 nanosheets can improve the catalytic activity of MoS2 by creating abundant defect sites both in the edge plane and the basal plane, as well as enhancing the electrical conductivity. In this paper, using Na2MoO4 , cysteine and GQDs as raw materials, a series of MoS2/GQDs composites were firstly synthesized via hydrothermal method, and then loaded …

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A Preliminary Study On Graphene Film-Metal Composites Prepared By Electrodeposition, Shuang-Juan Liu, Hai-Jing Wang, Jing Guo, Peng-Cheng Wang, Hao Zhou, Cai Meng, Han-Jie Guo Aug 2021

A Preliminary Study On Graphene Film-Metal Composites Prepared By Electrodeposition, Shuang-Juan Liu, Hai-Jing Wang, Jing Guo, Peng-Cheng Wang, Hao Zhou, Cai Meng, Han-Jie Guo

Journal of Electrochemistry

Graphene film (GF) has excellent electrical and thermal conductivity, but low strength and hardness. In order to obtain good comprehensive mechanical properties to improve the practical value of GF, the concept of preparing GF-metal composite materials was proposed. This work was conducted to preliminarily study the feasibility of using electrodeposition method to prepare GF-metal composites. Two kinds of composites, GF-Cu and GF-Cr, were successfully prepared by using GF as the cathode, and pure Cu and DSA (Dimensionally Stable Anode) as the anodes, respectively, with applying DC power externally. Employing certain electrochemical parameters, the cation in the electrolyte moved towards the …

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Preparation And Characterization Of Thermoplastic Polyurethane-Based Polymer Electrolyte, Li Zhou, Lie Wu, Zhao-Ming Xue Aug 2021

Preparation And Characterization Of Thermoplastic Polyurethane-Based Polymer Electrolyte, Li Zhou, Lie Wu, Zhao-Ming Xue

Journal of Electrochemistry

Electrolyte still has to be improved to satisfy the increasingly rigid demands of lithium ion batteries that have higher energy densities. Thermoplastic polyurethane (TPU) has two phase structures of soft segments and hard segments, which can guarantee the electrochemical and physical performances of electrolyte for lithium ion battery. It is now creatively applied to the gel polymer electrolyte matrix of lithium ion batteries. In this paper, a novel polymer membrane based on thermoplastic polyurethane/cellulose acetate (TPU/CA) was prepared by non-solvent induced phase separation (NIPS) method. Further, the TPU/CA blending gel polymer electrolyte (GPE) was prepared by absorbing liquid electrolyte. The …

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Preparation Of Coo/Rgo@Ni Foam Electrode And Its Electrocatalytic Reduction Of Co2, Qian Guo, Jia-Long Fu, Cheng-Yan Zhang, Chao-Yue Cai, Cheng Wang, Li-Hua Zhou, Rui-Bo Xu, Ming-Yan Wang Aug 2021

Preparation Of Coo/Rgo@Ni Foam Electrode And Its Electrocatalytic Reduction Of Co2, Qian Guo, Jia-Long Fu, Cheng-Yan Zhang, Chao-Yue Cai, Cheng Wang, Li-Hua Zhou, Rui-Bo Xu, Ming-Yan Wang

Journal of Electrochemistry

The worldwide extensive release of carbon dioxide (CO2) has caused serious environmental pollution and unprecedented climate change problems. Thus, for the sustainable development of human society, it is very necessary to convert CO2 to renewable fuels through clean and economical processes. The electrochemical CO2 reduction reaction (CO2RR) is regarded as a promising approach for the recycling of carbon resource and the generation of sustainable fuels. However, the slow kinetics and formation of multiple products in CO2RR hinder its large-scale application. Hence, great research efforts are made to develop electrocatalysts with high product …

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Preparation Of 3d Semi-Interpenetrated Polymer Networks Polymer Electrolyte For Lithium Metal Battery, Yun-Feng Zhang, Jia-Ying Wang, Xiao-Jie Li, Shi-Yu Zhao, Yang He, Shi-Kang Huo, Ya-Ying Wang, Chang Tan Aug 2021

Preparation Of 3d Semi-Interpenetrated Polymer Networks Polymer Electrolyte For Lithium Metal Battery, Yun-Feng Zhang, Jia-Ying Wang, Xiao-Jie Li, Shi-Yu Zhao, Yang He, Shi-Kang Huo, Ya-Ying Wang, Chang Tan

Journal of Electrochemistry

As the next generation high-energy batteries, lithium metal battery has attracted more and more attention due to its highest specific capacity (3860 mA·h·g-1) and the lowest anode potential (-3.04 V versus the standard hydrogen electrode, SHE). However, the safety problem caused by lithium dendrite growth is one of the biggest challenges for the commercialization of lithium metal batteries. Single ion conducting polymer electrolytes, which deliver high lithium ion transference number, represent one of the important strategies to inhibit lithium dendrite growth. However, the poor compatibility with electrodes and low ionic conductivity largely limit their practical application. In the …

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Study On Inhibition Of Lithium Dendrite Growth By Mg(No3)2 Additive In Carbonate Electrolyte, Biao Zhang, Yi Shuai, Yu Wang, Na-Chuan Yang, Kang-Hua Chen Aug 2021

Study On Inhibition Of Lithium Dendrite Growth By Mg(No3)2 Additive In Carbonate Electrolyte, Biao Zhang, Yi Shuai, Yu Wang, Na-Chuan Yang, Kang-Hua Chen

Journal of Electrochemistry

In the lithium-sulfurized polyacrylonitrile battery system, the formation and growth of lithium dendrites in the negative electrode seriously deteriorate the charge and discharge performance of the battery. If the growth of lithium dendrites pierces the separator and causes thermal runaway, it will also bring serious damage to the battery, causing potential safety risks. In the carbonate electrolyte that is more conducive to stabilizing the positive electrode sulfurized polyacrylonitrile material, the growth of lithium dendrites is particularly serious. In this paper, magnesium nitrate was added to the carbonate electrolyte to investigate the combined effect of nitrate and magnesium ions on the …

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A Comparison In Structural Transformation Of Li[NiXCoYMnZ]O2 (X = 0.6, 0.85) Cathode Materials In Lithium-Ion Batteries, Li-Juan Li, Zhen-Dong Zhu, Juan Dai, Rong-Rong Wang, Wen Peng Aug 2021

A Comparison In Structural Transformation Of Li[NiXCoYMnZ]O2 (X = 0.6, 0.85) Cathode Materials In Lithium-Ion Batteries, Li-Juan Li, Zhen-Dong Zhu, Juan Dai, Rong-Rong Wang, Wen Peng

Journal of Electrochemistry

In this paper, the phase transformation voltage ranges of two layered oxide ternary cathode materials, namely, Li(Ni0.85Co0.10Mn0.05)O2 (referred to Ni85, presenting high Ni content) and Li(Ni0.6Co0.2Mn0.2)O2 (referred to Ni60, presenting common low Ni content), were classified and determined. The structural differences between high Ni and common low Ni ternary materials were studied in order to understand the structure instability of high nickel material during the charging process. At the same time, the differential capacity (dQ·dV-1) curves of Ni85 and Ni60 positive …

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Effect Of Conductive Additives On Electrochemical Performance Of All-Solid-State Li-S Batteries, Dong-Hao Wang, He-Feng Yan, Zheng-Liang Gong Aug 2021

Effect Of Conductive Additives On Electrochemical Performance Of All-Solid-State Li-S Batteries, Dong-Hao Wang, He-Feng Yan, Zheng-Liang Gong

Journal of Electrochemistry

All-solid-state lithium sulfur batteries (ASSLSBs) with inorganic solid electrolytes offer an opportunity to realize both high energy density (lithium metal ~ 3860 mAh·g-1, sulfur ~ 1675 mAh·g-1), safety and reliability, via eliminating the polysulfides shuttle effect and flammable liquid electrolyte. However, it still remains a huge challenge for ASSLSBs to achieve high areal active mass loading, high utilization efficiency of the active materials and good cycle stability simultaneously due to the insulating nature of sulfur and Li2S (conductivities of sulfur and Li2S are 5×10-30 S·cm-1 and 3.6×10-7 S·cm-1 …

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Storage Performance And Mechanism Of Mose2 Nanospheres In Lithium And Magnesium Ion Batteries, Yi Peng, Wei Zhang, Fang-Zhen Zuo, Hao-Ying Lv, Kai-Jun Hong Aug 2021

Storage Performance And Mechanism Of Mose2 Nanospheres In Lithium And Magnesium Ion Batteries, Yi Peng, Wei Zhang, Fang-Zhen Zuo, Hao-Ying Lv, Kai-Jun Hong

Journal of Electrochemistry

Molybdenum diselenide (MoSe2) is a two-dimensional (2D) transition metal dichalcogenide (TMD) material, attracting wide attention in lithium ion battery (LIB) and exhibiting great potential in next-generation magnesium ion battery (MIB) due to its unique layered structure with fast ion mobility and weak van der Waals interlayer interaction. However, the reported literatures related to MoSe2 mainly focus on the enhancement of performance in LIB without deep storage mechanisms investigations. Meanwhile,the magnesium storage capacity and mechanisms have not been explored. In this work, MoSe2 nanospheres were synthesized via wet chemical route and followed by annealing treatment. When used …

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Computational Methodologies For The Simulation And Analysis Of Low-Frequency Vibrations In Molecular Crystals, Sara Jean Dampf Aug 2021

Computational Methodologies For The Simulation And Analysis Of Low-Frequency Vibrations In Molecular Crystals, Sara Jean Dampf

Dissertations - ALL

Quantum mechanical models are used to calculate a host of physical phenomena in molecular solids ranging from mechanical elasticity to the energetic stability ordering of polymorphs. However, with the many software packages and methodologies available, it can be difficult to select the most suitable model for the problem at hand without prior knowledge. A promising approach for evaluating the performance of solid-state models is the comparison of the simulations to experimentally measured low-frequency (sub-200 cm-1) vibrational spectra. As this region is dominated by weak intermolecular forces and shallow potential energy surfaces, even slight miscalculations in the solid-state packing arrangements can …

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Design And Development Of 2d Functional Semiconductor Nanocrystals, Andrew Hunter Davis Aug 2021

Design And Development Of 2d Functional Semiconductor Nanocrystals, Andrew Hunter Davis

Dissertations - ALL

Anisotropic nanocrystals (NCs) have become of keen interest in recent years, especially for applications in optoelectronic devices due to their directionally oriented emissions, narrow emission spectra, and suitable morphologies for device integration. Of the desired anisotropic NCs, two-dimensional (2D) NCs are of profound interest, due to their impressive optical and electronic properties as well as their prospective advantages towards applications in layered optoelectronic devices, such as solar cells. However, 2D NCs face many challenges, including limited synthetic derivation, as well as decreased stability and optical response, due to their large surface-to-volume ratio and reactive planar surface increasing surface defect state …

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Tuning Protein Dynamics To Sense Rapid Endoplasmic-Reticulum Calcium Dynamics, Xiaonan Deng, Xin-Qiu Joe Yao, Ken Berglund, Bin Dong, Daniel Ouedraogo, Mohammad A. Ghane, You Zhuo, Cheyenne Mcbean, Zheng Zachory Wei, Samer Gozem, Shan P. Yu, Ling Wei, Ning Fang, Angela M. Mabb, Giovanni Gadda, Donald Hamelberg, Jenny J. Yang Aug 2021

Tuning Protein Dynamics To Sense Rapid Endoplasmic-Reticulum Calcium Dynamics, Xiaonan Deng, Xin-Qiu Joe Yao, Ken Berglund, Bin Dong, Daniel Ouedraogo, Mohammad A. Ghane, You Zhuo, Cheyenne Mcbean, Zheng Zachory Wei, Samer Gozem, Shan P. Yu, Ling Wei, Ning Fang, Angela M. Mabb, Giovanni Gadda, Donald Hamelberg, Jenny J. Yang

Chemistry Faculty Publications

Multi-scale calcium (Ca2+) dynamics, exhibiting wide-ranging temporal kinetics, constitutes a ubiquitous mode of signal transduction. We report a novel endoplasmic-reticulum (ER)-targeted Ca2+ indicator, R-CatchER, which showed superior kinetics in vitro (koff≥2×103 s−1, kon≥7×106 M−1 s−1) and in multiple cell types. R-CatchER captured spatiotemporal ER Ca2+ dynamics in neurons and hotspots at dendritic branchpoints, enabled the first report of ER Ca2+ oscillations mediated by calcium sensing receptors (CaSRs), and revealed ER Ca2+-based functional cooperativity of CaSR. We elucidate the mechanism of R-CatchER and propose a principle to rationally design genetically encoded Ca2+ indicators with a single Ca2+-binding site …

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