A Density Functional Theory Study Of Intrinsically Chiral Semiconductor Nanocrystals,
2017
Wilfrid Laurier University
A Density Functional Theory Study Of Intrinsically Chiral Semiconductor Nanocrystals, Richard Edwards
Theses and Dissertations (Comprehensive)
A plethora of work has been done in the area of nanoparticles of late due to the fact that chemists (and physicists) have discovered that the properties of nanoparticles differ from both those of the bulk material and the atoms themselves. Nanoparticles have become of high interest for the use as catalysts while materials like graphene, being only one atom thick, have been shown to be great electrical conductors in comparison with the 3D structure of diamond. Among these peculiar nanoscale properties is the phenomenon of nanochirality, where a nanoparticle can exhibit chirality that does not extend to the macroscale …
In Situ Ph Determination Based On The Nmr Analysis Of ¹H-Nmr Signal Intensities And ¹⁹F-Nmr Chemical Shifts,
2017
Missouri University of Science and Technology
In Situ Ph Determination Based On The Nmr Analysis Of ¹H-Nmr Signal Intensities And ¹⁹F-Nmr Chemical Shifts, Ming Huang
Masters Theses
"The pH of an NMR sample can be measured directly by NMR experiments of signal intensities, chemical shifts, or relaxation time constants that depend on the pH. The 1H NMR peak intensities of the pH indicator phenolphthalein change as it changes from the OH-depleted form to the OH-rich form in the range of pH = 11.1 to 12.7. Because this range is rather small, another NMR technique was utilized based on 19F chemical shifts. The shift of F- in an aqueous solution of NaF changes in the alkaline range between pH = 11.0 and 14.0 and even …
Criegee Intermediate-Hydrogen Sulfide Chemistry At The Air/Water Interface,
2017
University of Nebraska–Lincoln
Criegee Intermediate-Hydrogen Sulfide Chemistry At The Air/Water Interface, Manoj Kumar, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We carry out Born–Oppenheimer molecular dynamic simulations to show that the reaction between the smallest Criegee intermediate, CH2OO, and hydrogen sulfide (H2S) at the air/water interface can be observed within few picoseconds. The reaction follows both concerted and stepwise mechanisms with former being the dominant reaction pathway. The concerted reaction proceeds with or without the involvement of one or two nearby water molecules. An important implication of the simulation results is that the Criegee-H2S reaction can provide a novel non-photochemical pathway for the formation of a C–S linkage in clouds and could be a …
Reply To ‘On The Bonding In Ligand-Protected Gold Clusters’,
2017
Shanghai Institute of Applied Physics
Reply To ‘On The Bonding In Ligand-Protected Gold Clusters’, Wen Wu Xu, Xiao Cheng Zeng, Yi Gao
Xiao Cheng Zeng Publications
In the recent Correspondence, Professor Henrik Grönbeck made several comments on the recently developed grand unified model (GUM), in particular using the ligand-protected gold cluster [Au25(SR)18]1− as an example. We noted that the latter cluster can be viewed as belonging to a special group of ligand-protected gold clusters that contain one or several icosahedral Au13 motifs. For this group of clusters, a secondary block Au13(8e) has been identified as a more convenient way to describe their structure anatomy and evolution. Another extension of the GUM is the identification of the new elementary …
Approaches Toward Novel 1,2,3-Triazole Sensors For The Detection Of Anions And Heavy Metal Cations,
2017
Georgia Southern University
Approaches Toward Novel 1,2,3-Triazole Sensors For The Detection Of Anions And Heavy Metal Cations, Richard D. Govan
College of Graduate Studies: Theses & Dissertations
Cations and anions play pivotal roles in biological and physiological processes, however an imbalance in concentration of any ion can be detrimental. Therefore, research into the selective recognition of anions and heavy metal cations has acquired much attention. One approach involves the use of chemosensors. Upon interaction with targeted analytes, chemosensors produce a distinct response, in some cases a fluorescent or colorimetric signal. The 1,2,3-triazole unit has much potential as a chemical sensor due to its unique photophysical properties. The specificity, selectivity, and signaling mechanism of triazole sensors can be tuned with conjugation in the motif and choice and placement …
Electrochemical Behaviors And Determinations Of Terbutaline Sulfate At Poly Eriochrome Black T Modified Electrode,
2016
Department of Pharmaceutical Analysis of Fujian Medical University, Fuzhou 350108, China; The Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Fujian Medical University, Fuzhou 350108, China;
Electrochemical Behaviors And Determinations Of Terbutaline Sulfate At Poly Eriochrome Black T Modified Electrode, Yan-Jie Zheng, Hong Yao, Shao-Huang Weng, Hua-Ping Peng, Shi-Wen Gong, Li Huang, Qiang Dai, Xin-Hua Lin
Journal of Electrochemistry
The poly eriochrome black T modified electrode was prepared by electropolymerization. This modified electrode was characterized by scanning electron microscopy(SEM), electrochemical impedance spectroscopy(EIS) and cyclic voltammetry (CV). The electrochemical behaviors of terbutaline sulfate were studied by CV, while the recoveries were measured by differential pulse voltammetry (DPV). The modified electrode shows excellent electrocatalytic characteristics for terbutaline sulfate. In pH 7.0 phosphate buffer solution, the oxidation peak currents obtained by DPV were linear to the terbutaline sulfate concentrations over the range of 1.2x10-7~2.0x10-6 mol•L-1. The detection limit was estimated to be 1.5x10-8 mol•L-1 and …
Stm Investigation Of Oxygen Reduction Reaction On Solid Interface In Fuel Cell,
2016
CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;University of Chinese Academy of Sciences, Beijing 100049, China;
Stm Investigation Of Oxygen Reduction Reaction On Solid Interface In Fuel Cell, Zhen-Feng Cai, Bing Sun, Wen-Jie Jiang, Ting Chen, Dong Wang, Li-Jun Wan
Journal of Electrochemistry
An electrocatalyst for oxygen reduction reaction (ORR) is an important component for fuel cells. An investigation at interfacial electrochemical reactions toward ORR at a molecular scale benefits mechanistic understanding as well as rational design of catalysts. Scanning tunneling microscopy (STM) has been proven to be a powerful tool to monitor chemical reactions and to provide in-situ information about the interfacial electrochemical reactions at a molecular level. This review summarizes the recent STM studies in monitoring the interface processes such as morphological changes, molecular changes, reaction intermediates, and oxidation products. The prospects of future development in this field are outlined.
Chitosan/Nonahydrate Gel Derived Fe-N-Doped Porous Carbon Sheet As High-Efficient Orr Electrocatalyst,
2016
Key Laboratory of Automobile Materials, Ministry of Education and College of Materials Science and Engineering, Jilin University, Changchun 130012, China;State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130012, China;
Chitosan/Nonahydrate Gel Derived Fe-N-Doped Porous Carbon Sheet As High-Efficient Orr Electrocatalyst, Fan-Lu Meng, Xin-Bo Zhang, Jun-Min Yan
Journal of Electrochemistry
The chitosan/nonahydrate gel was used as a precursor to realize the uniform mixture of N-polymer and metal salt. After lyophilization treatment, the gel went through heat treatment and acid etch. Accordingly, the Fe-N-doped porous carbon sheet with homogenous composition and microstructure was prepared. Compared with the commercial Pt/C catalyst, the Fe-N-doped porous carbon sheet exhibited more positive onset potential and half-wave potential, higher current density, and especially, excellent durability. The power density of 318 mW·cm-2 was obtained in alkaline fuel cell with the Fe-N-doped porous carbon sheet as a cathode catalyst, which is higher than 267 mW·cm-2 with …
Synthesis Of Ultrathin Co3O4 Nanoflakes Film Material For Electrochemical Sensing,
2016
College of Electrical Engineering, Yanshan University, Qinhuangdao 066004, Hebei, China;Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004, Hebei, China.;
Synthesis Of Ultrathin Co3O4 Nanoflakes Film Material For Electrochemical Sensing, Hui-Juan Wang
Journal of Electrochemistry
Ultrathin cobalt oxide (Co3O4) nanoflakes film material was synthesized by using an electro-deposited cobalt layer as a raw material through a simple oxidation method and followed by a heat treatment at 350 oC. The physical characterizations of the Co3O4 nanoflakes film were performed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) technologies, and the electrochemical activity was measured by cyclic voltammetry (CV). As a promising material for electrochemical sensing, the as-synthesized ultrathin Co3O4 nanoflakes film material exhibited excellent electrochemical activity for H2O …
Special Issue On Interfacial Electrochemistry,
2016
Xiamen University, Xiamen, 361005, China;
Special Issue On Interfacial Electrochemistry, Bing-Wei Mao
Journal of Electrochemistry
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Lithium-Sulfur (Selenium) Batteries: Interface Issues And Solving Strategies,
2016
CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Science, Beijing 100190, China;
Lithium-Sulfur (Selenium) Batteries: Interface Issues And Solving Strategies, Nian-Wu Li, Ya-Xia Yin, Yu-Guo Guo
Journal of Electrochemistry
The stable interface is still a challenge for lithium-sulfur (selenium) batteries because of the low conductivity of sulfur (selenium), dissolution of polysulfide (polyselenide), volume expansion of sulfur (selenium), and lithium dendrite growth. This review describers some recent developments in lithium-sulfur (selenium) batteries and highlights our efforts in this field. The possible strategies for building stable interface in the lithium-sulfur (selenium) batteries including nano-restriction effect, chemical bonding, interface adsorption, surface coating, electrolyte optimization, and Lithium anode treatment have been discussed.
Syntheses Of Ag@Pd@Pt Nanoparticles With Tunable Shell Thickness For Electrochemical Oxidation Of Formic Acid,
2016
State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China;
Syntheses Of Ag@Pd@Pt Nanoparticles With Tunable Shell Thickness For Electrochemical Oxidation Of Formic Acid, Xiao-Dong Lin, Du-Hong Chen, Zhong-Qun Tian
Journal of Electrochemistry
In an effort to lower cost of a catalyst, the silver (Ag) core with palladium (Pd) layer then platinum (Pt) island (Ag@Pd@Pt) nanoparticles were synthesized and the electrocatalytic activity of Ag@Pd@Pt nanoparticles on formic acid was compared with that of Au@Pd@Pt nanoparticles reported previously. The results showed that the existence of a small amount of Pt could significantly improve the activity of the catalyst. When the surface coverage of Pt approached 0.5 monolayers, the activity of Ag@Pd@Pt nanoparticles reached the maximum. Though the onset potential of the electro-oxidation was slightly more positive (about 50 mV), the overall electrocatalytic activity of …
Investigation On Laser Induced Deposition Of Cu-Based Materials At [Bmim]Bf4/Pt Electrode Interface,
2016
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, Jiangsu, China;
Investigation On Laser Induced Deposition Of Cu-Based Materials At [Bmim]Bf4/Pt Electrode Interface, Min-Min Xu, Jin-Hua Mei, Jian-Lin Yao, Ren-Ao Gu
Journal of Electrochemistry
By controlling the negative potential, Cu-based materials were deposited at the [BMIm]BF4/Pt electrode interface under the laser irradiation. The effects of laser power and irradiation time on the yield of deposition products were studied by using different laser powers and different irradiation time. The product yield could be directly determined by the size of deposition point through the observation from the optical microscope. Further mechanism study combined with the formula deduced that the thermal effect of the laser could make the electrode surface temperature rise 110 degrees, which can promote the occurrence of electrodeposition. By SEM characterization, the …
Intrinsic Interfacial Property Between High-Voltage Lini0.5Mn1.5O4 Cathode And Electrolyte,
2016
i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215125, China; University of Science and Technology of China, Nanoscience and Technology Institute, Suzhou, Jiangsu 215125, China;
Intrinsic Interfacial Property Between High-Voltage Lini0.5Mn1.5O4 Cathode And Electrolyte, Li Li, Jing-Jing Xu, Shao-Jie Han, Wei Lu, Li-Wei Chen
Journal of Electrochemistry
To obtain high energy density, developing high-voltage cathode materials is an effective approach. The cathode/electrolyte interface stability is the key factor for the cycle performance and safety performance of high-voltage lithium ion batteries. It is, therefore, of significant importance to study the stability of cathode/electrolyte interface. However, many reports have shown that at the cathode/electrolyte interface the cathodes were prepared by coating the mixture of active materials with a conductive additive and a binder on an Al current collector. The introduction of additives will interfere the surface morphology and component analyses, resulting in difficulty to acquire the intrinsic information at …
Hydrogen Evolution Properties On Individual Mos2 Nanosheets,
2016
Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Hubei Key Laboratory of Electrochemical Power Sources, Department of Chemistry, Wuhan University, Wuhan 430072, China.;
Hydrogen Evolution Properties On Individual Mos2 Nanosheets, Yu Gao, Juan Zhou, Yu-Wen Liu, Sheng-Li Chen
Journal of Electrochemistry
Molybdenum disulfide (MoS2) has been acknowledged to play important roles in hydrogen evolution reaction (HER) for hydrogen energy technology. Both computational and experimental results have suggested that the promising catalytic activity of MoS2 for the HER could be attributed to the sulfur edges of two-dimensional nanosheets, while their basal planes were catalytically inert. In order to verify this conclusion, we prepared single MoS2 sheet electrodes which were made of individual MoS2 sheets attached on the self-assembly monolayers (SAM) of SH(CH2)15COOH at Au ultramicroelectrodes (Au/SAM/MoS2). The single MoS2 sheet …
An Stm Study On The Structure Of Pt(100)/Ionic Liquid Omipf6 Interface,
2016
College of Chemistry and Chemical Engineering, State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, 361005;
An Stm Study On The Structure Of Pt(100)/Ionic Liquid Omipf6 Interface, Jin Peng, Mian-Gang Li, Li-Qiang Xie, Jia-Wei Yan, Bing-Wei Mao
Journal of Electrochemistry
Potential-dependent structures of Pt(100)/ionic liquid 1-methyl-3-octylimidazolium hexafluorophosphate (OMIPF6) interface have been studied by electrochemical scanning tunneling microscopy (ECSTM). The cation OMI+ forms ordered structure on Pt(100) surface, which exists in a potential region of about 1.2 V. When the potential is more negative than -0.6 V, it can be seen that the ordered structure transforms to disordered structure. When the potential shifts positively to +0.6 V, the desorption of cations OMI+ occurs, which indicates that strong electrostatic repulsion is needed to overcome chemical interaction between OMIPF6 and Pt(100) surface, leading to the desorption. The above results …
A Study On The Oxidation Of Hydrogen Peroxide At Au(111) And Au(100) Electrodes,
2016
Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, China;
A Study On The Oxidation Of Hydrogen Peroxide At Au(111) And Au(100) Electrodes, Yong-Li Zheng, Jie Wei, Yan-Xia Chen
Journal of Electrochemistry
The oxidation reactions of hydrogen peroxide (H2O2) at Au(111) and Au(100) electrodes in 0.1 mol·L-1 HClO4 were investigated by using rotating disk electrode system. It was found that H2O2 could be readily oxidized to O2 at both Au(100) and Au(111) surfaces with the onset potential close to its equilibrium potential. In contrast, the onset overpotential for H2O2 reduction was above 0.4 V, while the onset overpotential for H2O2 oxidation at Au(100) was ca. 0.1 V more negative than that at Au(111), this is probably …
Lithium Plating Identification From Degradation Behaviors Of Lithium-Ion Cells,
2016
Beijing Co-innovation Center for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China
Lithium Plating Identification From Degradation Behaviors Of Lithium-Ion Cells, Jian-Bo Zhang, Lai-Suo Su, Xin-Yu Li, Hao Ge, Ya-Kun Zhang, Zhe Li
Journal of Electrochemistry
Lithium plating has huge impact on the lifetime and safety of lithium-ion cells. It is, therefore, necessary to identify lithium plating. In this study, the accelerated stress tests of lithium-ion cells were conducted under different conditions with multi-stress loads. Based on the different effects of the two major aging mechanisms, namely, SEI (Solid Electrolyte Interface) layer growth and lithium plating, on the degradation behaviors, two lithium plating identification methods of resistance-capacity plot and Arrhenius plot were employed. The experimental results revealed that the two identification methods are highly consistent with each other. Furthermore, the origins of capacity loss were distinguished …
A Grand Unified Model For Liganded Gold Clusters,
2016
University of Nebraska-Lincoln
A Grand Unified Model For Liganded Gold Clusters, Wen Wu Xu, Beien Zhu, Xiao Cheng Zeng, Yi Gao
Xiao Cheng Zeng Publications
A grand unified model (GUM) is developed to achieve fundamental understanding of rich structures of all 71 liganded gold clusters reported to date. Inspired by the quark model by which composite particles (for example, protons and neutrons) are formed by combining three quarks (or flavours), here gold atoms are assigned three ‘flavours’ (namely, bottom, middle and top) to represent three possible valence states. The ‘composite particles’ in GUM are categorized into two groups: variants of triangular elementary block Au3(2e) and tetrahedral elementary block Au4(2e), all satisfying the duet rule (2e) of the valence shell, akin to …
Computational Quantum Chemistry Studies Of The Stabilities Of Radical Intermediates Formed During The Oxidation Of Melatonin,
2016
East Tennessee State University
Computational Quantum Chemistry Studies Of The Stabilities Of Radical Intermediates Formed During The Oxidation Of Melatonin, Constance E. Warden
Electronic Theses and Dissertations
Melatonin, a nontoxic natural antioxidant, is of interest as a possible spin trap for use in spectroscopic methods to observe and identify short-lived free radicals, which have been linked to oxidative stress that may result in serious health problems. However, the reaction mechanisms for the oxidation of melatonin to form the product N1-acetyl-N2-formyl-5-methoxykynuramine are still not well understood. Computational quantum chemistry studies have been done on four proposed reaction mechanisms, involving the following major intermediate structures: a dioxetane, an epoxide, a melatonin radical cation, and a spin radical adduct. Molecular geometries were optimized at the …
