Surprising Impact Of Remote Groups On The
Folding–Unfolding And Dimer-Chain Equilibria Of
Bifunctional H-Bonding Unimers,
2016
State University of New York
Surprising Impact Of Remote Groups On The Folding–Unfolding And Dimer-Chain Equilibria Of Bifunctional H-Bonding Unimers, Rui Liu, Shuang Cheng, Erin S. Baker, Richard D. Smith, Xiao Cheng Zeng, Bing Gong
Xiao Cheng Zeng Publications
Oligoamide 1, consisting of two H-bonding units linked by a trimethylene linker, was previously found to form a very stable, folded dimer. In this work, replacing the side chains and end groups of 1 led to derivatives that show the surprising impact of end groups on the folding and dimer-chain equilibria of the resultant molecules.
Unraveling The Hidden Function Of A Stabilizer In A
Precursor In Improving Hybrid Perovskite Film
Morphology For High Efficiency Solar Cells,
2016
University of Nebraska-Lincoln
Unraveling The Hidden Function Of A Stabilizer In A Precursor In Improving Hybrid Perovskite Film Morphology For High Efficiency Solar Cells, Zhengguo Xiao, Dong Wang, Qingfeng Dong, Qi Wang, Wei Wei, Jun Dai, Xiwei Zheng, Jinsong Huang
Xiao Cheng Zeng Publications
The morphology of the organometal trihalide perovskite (OTP) plays a critical role in the performance of solar cell devices. Nevertheless it has been frequently reported that the morphology of OTP films tends to be different in different laboratories even with the same film preparation procedure, which makes it very difficult to compare and understand the material and device physics. Here, we unravel a critical role of the H3PO2 stabilizer in HI, which has been largely ignored, in controlling the morphology of the perovskite films. The H3PO2 stabilizer in HI solution introduces MAH2PO …
Two-Dimensional Interlocked Pentagonal Bilayer Ice:
How Do Water Molecules Form A Hydrogen Bonding Network?,
2016
University of Science and Technology of China
Two-Dimensional Interlocked Pentagonal Bilayer Ice: How Do Water Molecules Form A Hydrogen Bonding Network?, Weiduo Zhu, Wen- Hui Zhao, Lu Wang, Di Yin, Min Jia, Jinlong Yang, Xiao Cheng Zeng, Lan-Feng Yuan
Xiao Cheng Zeng Publications
The plethora of ice structures observed both in bulk and under nanoscale confinement reflects the extraordinary ability of water molecules to form diverse forms of hydrogen bonding networks. An ideal hydrogen bonding network of water should satisfy three requirements: (1) four hydrogen bonds connected with every water molecule, (2) nearly linear hydrogen bonds, and (3) tetrahedral configuration for the four hydrogen bonds around an O atom. However, under nanoscale confinement, some of the three requirements have to be unmet, and the selection of the specific requirement(s) leads to different types of hydrogen bonding structures. According to molecular dynamics (MD) simulations …
Near-Barrierless Ammonium Bisulfate Formation Via A Loop-Structure Promoted Proton-Transfer Mechanism On The Surface Of Water,
2016
University of Nebraska–Lincoln
Near-Barrierless Ammonium Bisulfate Formation Via A Loop-Structure Promoted Proton-Transfer Mechanism On The Surface Of Water, Lei Li, Manoj Kumar, Chongqin Zhu, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
In the atmosphere, a well-known and conventional pathway toward the formation of ammonium sulfate is through the neutralization of sulfuric acid with ammonia (NH3) in water droplets. Here, we present direct ab initio molecular dynamics simulation evidence of the formation of ammonium bisulfate (NH4HSO4) from the hydrated NH3 and SO3 molecules in a water trimer as well as on the surface of a water droplet. This reaction suggests a new mechanism for the formation of ammonium sulfate in the atmosphere, especially when the concentration of NH3 is high (e.g., ∼10 μg …
Resolving The Hono Formation Mechanism In The
Ionosphere Via Ab Initio Molecular Dynamic Simulations,
2016
Southwest University
Resolving The Hono Formation Mechanism In The Ionosphere Via Ab Initio Molecular Dynamic Simulations, Rongxing He, Lei Li, Jie Zhong, Chongqin Zhu, Joseph S. Francisco, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Solar emission produces copious nitrosonium ions (NO+) in the D layer of the ionosphere, 60 to 90 km above the Earth’s surface. NO+ is believed to transfer its charge to water clusters in that region, leading to the formation of gaseous nitrous acid (HONO) and protonated water cluster. The dynamics of this reaction at the ionospheric temperature (200–220 K) and the associated mechanistic details are largely unknown. Using ab initio molecular dynamics (AIMD) simulations and transition-state search, key structures of the water hydrates—tetrahydrate NO+(H2O)4 and pentahydrate NO+(H2O)5 …
Probing The Structures Of Gold–Aluminum Alloy
Clusters AuXAlY−: A Joint Experimental And Theoretical
Study,
2016
University of Nebraska-Lincoln
Probing The Structures Of Gold–Aluminum Alloy Clusters AuXAlY−: A Joint Experimental And Theoretical Study, Navneet S. Khetrapal, Tian Jian, Rhitankar Pal, Gary V. Lopez, Seema Pande, Lai-Sheng Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Besides the size and structure, compositions can also dramatically affect the properties of alloy nanoclusters. Due to the added degrees of freedom, determination of the global minimum structures for multi-component nanoclusters poses even greater challenges, both experimentally and theoretically. Here we report a systematic and joint experimental/theoretical study of a series of gold–aluminum alloy clusters, AuxAly−(x + y = 7,8), with various compositions (x = 1–3; y = 4–7). Well-resolved photoelectron spectra have been obtained for these clusters at different photon energies. Basin-hopping global searches, coupled with density functional theory calculations, are used …
Improved High Temperature Stability Of Anatase Tio2 Photocatalysts By N, F, P Co-Doping,
2016
Technological University Dublin
Improved High Temperature Stability Of Anatase Tio2 Photocatalysts By N, F, P Co-Doping, Rachel Fagan, Declan Mccormack, Steven Hinder, Suresh Pillai
Articles
Among the three commonly occurring phases (anatase, rutile, and brookite) of TiO2, the anatase form is reported to be the best photocatalyst due to the improved charge-carrier mobility and the greater number of surface hydroxyl groups. The anatase to rutile transition in titania photocatalysts usually occurs at a temperature between 500 °C to 700 °C. Development of a high temperature stable (above 1000 °C) anatase phase is important for various environmental applications (e.g. self-cleaning ceramic tiles, anti-microbial sanitary wares, etc.). In this study, the use of ammonium hexafluorophosphate as a single source dopant (method A) and urea, trifluoroacetic acid and …
Understanding Electrical Conduction In Lithium Ion Batteries Through Multi-Scale Modeling,
2016
University of Kentucky
Understanding Electrical Conduction In Lithium Ion Batteries Through Multi-Scale Modeling, Jie Pan
Theses and Dissertations--Chemical and Materials Engineering
Silicon (Si) has been considered as a promising negative electrode material for lithium ion batteries (LIBs) because of its high theoretical capacity, low discharge voltage, and low cost. However, the utilization of Si electrode has been hampered by problems such as slow ionic transport, large stress/strain generation, and unstable solid electrolyte interphase (SEI). These problems severely influence the performance and cycle life of Si electrodes. In general, ionic conduction determines the rate performance of the electrode, while electron leakage through the SEI causes electrolyte decomposition and, thus, causes capacity loss. The goal of this thesis research is to design Si …
Atomic Oxygen Adsorption And Absorption On Rh(111) And Ag(111),
2016
Loyola University Chicago
Atomic Oxygen Adsorption And Absorption On Rh(111) And Ag(111), Jonathan Derouin
Dissertations
A central question in the field of heterogeneous catalysis is how surface structure and subsurface species influence catalytic behavior. One key to answering that question is determining which surface structures and subsurface species are present under catalytically relevant conditions. This dissertation presents results of Auger electron spectroscopy, low energy electron diffraction, temperature programmed desorption, and scanning tunneling microscopy experiments on oxidized Rh(111) and Ag(111) crystals. Exposing Rh(111) to O2 produced a predominately (2 × 1) adlayer, but even after extended dosing, (2 × 2) domains were also present. Exposing Rh(111) to atomic oxygen yielded O coverages greater than 0.5 ML …
Probing Allosteric, Partial Inhibition Of Thrombin Using Novel Anticoagulants,
2016
Virginia Commonwealth University
Probing Allosteric, Partial Inhibition Of Thrombin Using Novel Anticoagulants, Stephen S. Verespy Iii
Theses and Dissertations
Thrombin is the key protease that regulates hemostasis; the delicate balance between procoagulation and anticoagulation of blood. In clotting disorders, like deep vein thrombosis or pulmonary embolism, procoagulation is up-regulated, but propagation of clotting can be inhibited with drugs targeting the proteases involved, like thrombin. Such drugs however, have serious side effects (e.g., excessive bleeding) and some require monitoring during the course of treatment. The reason for these side effects is the mechanism by which the drugs’ act. The two major mechanisms are direct orthosteric and indirect allosteric inhibition, which will completely abolish the protease’s activity. Herein we sought an …
Interactions Of The Naphthalene Radical Cation With Polar And Unsaturated Molecules In The Gas Phase,
2016
Virginia Commonwealth University
Interactions Of The Naphthalene Radical Cation With Polar And Unsaturated Molecules In The Gas Phase, Sean P. Platt
Theses and Dissertations
Characterizing the interactions of solvent molecules with ions is fundamental in understanding the thermodynamics of solution chemistry. These interactions are difficult to observe directly in solution because the number of solvent molecules far exceed that of ions. This lend the gas phase to be the ideal medium in the study ion-solvent interactions on a molecular level. Ionized polycyclic aromatic hydrocarbon (PAH) molecules can readily form hydrogen bonds with neutral solvent molecules in aqueous and interstellar medium. Previous research has been done for stepwise solvation of small molecules such as benzene+, pyridine, and phenylacetylene. The similarity in these results …
Systematic Postsynthetic Modification Of Nanoporous Organic Frameworks And Their Performance Evaluation For Selective Co2 Capture,
2016
Virginia Commonwealth University
Systematic Postsynthetic Modification Of Nanoporous Organic Frameworks And Their Performance Evaluation For Selective Co2 Capture, Timur Islamoglu
Theses and Dissertations
Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO2 interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO2 capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups …
Laser Vaporization Controlled Condensation And Laser Irradiation In Solution For The Synthesis Of Supported Nanoparticle Catalysts,
2016
Virginia Commonwealth University
Laser Vaporization Controlled Condensation And Laser Irradiation In Solution For The Synthesis Of Supported Nanoparticle Catalysts, Vitaly Kisurin Mr.
Theses and Dissertations
Solid catalyst supports of SiOx-RGO (Reduced Graphene Oxide) and UiO-67 (Universitet i Oslo) have been successfully synthesized and were loaded with palladium nanoparticles to test for a series of heterogeneous reactions. The SiOx/RGO catalysts were synthesized through laser ablation of silicon and graphite oxide micron powder and UiO-67 metal-organic framework (MOF) was synthesized through mixing of precursors with DMF/HCl solution and washing the resultant powder from impurities. The SiOx/RGO supports were later impregnated with palladium precursors which were then subject to Microwave Irradiation (MWI). The UiO-67 framework was impregnated with palladium precursors and was irradiated with pulsed Nd:YAG 532 nm …
The Role Of Organic Matter In The Surface Chemistry Of Arsenic Compounds On Iron−(Oxyhydr)Oxides Studied By Atr-Ftir,
2016
Wilfrid Laurier University
The Role Of Organic Matter In The Surface Chemistry Of Arsenic Compounds On Iron−(Oxyhydr)Oxides Studied By Atr-Ftir, Arthur Situm
Theses and Dissertations (Comprehensive)
The interaction of organic matter with the interfaces of active soil components such as iron oxides is ubiquitous within soil environments. The presence of organics at these interfaces may have implications for other soil constituents whose mobility is controlled by their ability to bind to active soil components. Most of the studies performed to date which look at these interactions are bulk/batch studies performed ex-situ. Attenuated total internal reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was utilized within this work to study interactions between select model organics (citrate, oxalate and pyrocatechol) and iron−(oxyhydr)oxides, as well as their effect on the surface …
Spontaneous Helix Formation In Non-Chiral Bent-Core Liquid Crystals With Fast Linear Electro-Optic Effect,
2016
Department of Electronic and Electrical Engineering, Trinity College Dublin, Ireland
Spontaneous Helix Formation In Non-Chiral Bent-Core Liquid Crystals With Fast Linear Electro-Optic Effect, Sithara P. Sreenilayam, Yuri Panarin, Jagdish K. Vij, Vitaly P. Panov, Anne Lehmann, Marco Poppe, Marko Prehm, Carsten Tschierske Carsten Tschierske
Articles
Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of …
Kinetic Decay Of A Polymer/Ink Complex As An O2 Indicator,
2016
Central Washington University
Kinetic Decay Of A Polymer/Ink Complex As An O2 Indicator, Becca Hoene
All Master's Theses
Indicator inks are an important part of the continued consumption of packaged goods. This thesis is focused on understanding the kinetics and reaction mechanism for a unique indicator ink that is based upon the oxidation of indigotetrasulfonate (ITS) encapsulated in the polyelectrolyte poly(diallyldimethylammonium chloride) (polyDADMAC). Sodium bisulfite (NaHSO3) was used as the initial oxygen scavenger and to drive the reduction of the ITS. Studies were predominantly done in solution phase through the dilution of the ink systems. Fluorescence spectroscopy was the primary method used to determine the kinetic decay rates and interaction between the ITS dye molecules and …
Special Issue: Electrochemistry Of Carbon Materials,
2015
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;
Special Issue: Electrochemistry Of Carbon Materials, Wei Chen
Journal of Electrochemistry
Carbon materials are traditional electrode materials due to their excellent electrical conductivities, high electrochemical stabilities and wide potential windows. Glassy carbon, graphite, various activated charcoals, carbon fibers etc. have been widely used in electrochemistry serving as electrode substrates or supports. In addition to their applications in basic electrochemistry, carbon materials have also played important roles in electrochemical energy storage and conversion. In recent years, various types of carbon structures, from zero-dimensional carbon nanodots, one-dimensional nanotubes, two-dimensional graphene to three-dimensional porous carbons, have attracted increasing attention in electrochemical field. It has been found that carbon materials have outstanding properties as advanced …
Applications Of Carbon Materials In Electrochemical Energy Storage,
2015
Advanced Carbon Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
Applications Of Carbon Materials In Electrochemical Energy Storage, Ji Liang, Lei Wen, Hui-Ming Cheng, Feng Li
Journal of Electrochemistry
An electrode material for electrochemical energy storage is one of the key components for high performance devices. In a variety of electrochemical energy storage systems, carbon materials, especially the lately emerged carbon nanomaterials including the carbon nanotube and graphene, have been playing a very important role and brought new vitality to the development and demonstration of the broad application prospects. In this review, we summarize the applications of various carbon materials in the typical electrochemical energy storage devices, namely lithium/sodium ion batteries, supercapacitors, and lithium-sulfur batteries, as well as flexible electrochemical energy storage and electrochemical catalysis. A perspective of novel …
Colloidal Ionic Supercapacitors,
2015
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;
Colloidal Ionic Supercapacitors, Kun-Feng Chen, Dong-Feng Xue
Journal of Electrochemistry
Supercapacitors have high power density and long cycle life compared with battery systems, but they still suffer from low energy density at the same time. In order to increase the energy density of supercapacitors, we have developed a new type of pseudocapacitor, called colloidal ion supercapacitor, which can directly use commercial metal salts as electrode materials and form electroactive matter by in-situ electrochemical reactions without the need of additional materials synthesis processes. Colloidal ion supercapacitor can fully utilize the redox reaction of metal cations with multiple oxidation states, which can completely release the stored electrical energy of multiple-valence cations, leading …
Electrodeposition Of Lanthanum In Deep Eutectic Solvents,
2015
Guangxi Key Laboratory of Low Carbon Energy Materials, College of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, guangxi, China;State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China;
Electrodeposition Of Lanthanum In Deep Eutectic Solvents, Li Wang, You-Jun Fan, Lu Wei, Hai-Xia Liu, Shi-Gang Sun
Journal of Electrochemistry
With the choline chloride/urea deep eutectic solvents (DESs) as the medium, the olive-like lanthanum particles with uniform shape and size were successfully prepared through a potentiostatic deposition method. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). At the same time, the effect of deposition potential, temperature and time on the size and morphology of samples was investigated. The results demonstrated that the optimum conditions for the preparation of olive-like lanthanum particles were as follows: deposition potential of -1.7 V, temperature of 80 °C and …
