41 results on '"Zhuang Wang"'
Search Results
2. Extraction and Complexation Investigation of Palladium(II) by a Nitrilotriacetate-Derived Triamide Ligand
- Author
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Xueyu Wang, Lianjun Song, Long Li, Zhuang Wang, Qiuju Li, Lanlan He, Xuanhao Huang, and Songdong Ding
- Subjects
Inorganic Chemistry ,Spectroscopy, Fourier Transform Infrared ,Indicators and Reagents ,Physical and Theoretical Chemistry ,Crystallography, X-Ray ,Ligands ,Palladium - Abstract
Effective and selective separation and recovery of the fission product palladium from high-level liquid waste are conducive not only to reducing its hazards to the public health and environment but also to alleviate the pressure on the increasing demand for natural palladium. Herein, the Pd
- Published
- 2022
3. Tuning the Saturated Vapor Pressure of Solvothermal Synthesis to Boost the Thermoelectric Performance of Pristine Bi2Te3 Polycrystals by Anisotropy Strengthening
- Author
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Jing Yuan, Xiao-Lei Shi, De-Zhuang Wang, Wei-Di Liu, Meng Li, Wenyi Chen, Qishuo Yang, Yifeng Wang, Qingfeng Liu, and Zhi-Gang Chen
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Materials Chemistry ,Electrochemistry ,Energy Engineering and Power Technology ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering - Published
- 2023
4. Europium(III)/Terbium(III) mixed metal-organic frameworks and their application as a ratiometric thermometer
- Author
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Madhura Joshi, Zhuang Wang, Florian M. Wisser, Maurizio Riesner, Rebecca Reber, Marcus Fischer, Rachel Fainblat, Karl Mandel, Doris Segets, Gerd Bacher, and Martin Hartmann
- Abstract
The ability to molecularly engineer luminescent metal-organic frameworks is a powerful tool for the design of better performing rational temperature sensors. Lanthanide based MOF stand out as luminescent temperature sensors due to the high luminescence intensity and sharp emission lines of the lanthanides. The use of two different lanthanide cations incorporated into the same MOF structure is supposed to allow for a rational, that is self-referencing, temperature sensing. Here, we present series of mixed EuxTb(1-x)BTC, which were designed as nanoparticles. The EuxTb(1-x)BTC series shows controllable luminescent properties, which depend on the solvation of the lanthanide. The two MOFs in the series with the lowest Eu content, i.e. Eu0.04Tb0.96BTC and Eu0.02Tb0.98BTC, are suitable candidates for rational temperature sensing in the range between 200 and 270 K and above 300 K.
- Published
- 2023
5. Highly Asymmetric Graphene Layer Doping and Band Structure Manipulation in Rare Earth–Graphene Heterostructure by Targeted Bonding of the Intercalated Gadolinium
- Author
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Marek Kolmer, Benjamin Schrunk, Myron Hupalo, Joseph Hall, Shen Chen, Jianhua Zhang, Cai-Zhuang Wang, Adam Kaminski, and Michael C. Tringides
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General Energy ,Physical and Theoretical Chemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2022
6. Straintronic Effect on Phonon-Mediated Superconductivity of Nb2CT2 (T = O, S, Se, or Te) MXenes
- Author
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Sheng-Yan Wang, Chen Pan, Hui Tang, Hong-Yun Wu, Guo-Yong Shi, Kun Cao, Hong Jiang, Yue-Hua Su, Chao Zhang, Kai-Ming Ho, and Cai-Zhuang Wang
- Subjects
General Energy ,Physical and Theoretical Chemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2022
7. High Energy Density in Combination with High Cycling Stability in Hybrid Supercapacitors
- Author
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Guang Cong Zhang, Man Feng, Qing Li, Zhuang Wang, Zixun Fang, Zhimin Niu, Nianrui Qu, Xiaoyong Fan, Siheng Li, Jianmin Gu, Jidong Wang, and Desong Wang
- Subjects
General Materials Science - Abstract
Hybrid supercapacitors are considered the next-generation energy storage equipment due to their superior performance. In hybrid supercapacitors, battery electrodes need to have large absolute capacities while displaying high cycling stability. However, enhancing areal capacity via decreasing the size of electrode materials results in reductions in cycling stability. To balance the capacity-stability trade-off, rationally designed proper electrode structures are in urgent need and still of great challenge. Here we report a high-capacity and high cycling stability electrode material by developing a nickel phosphate lamination structure with ultrathin nanosheets as building blocks. The nickel phosphate lamination electrode material exhibits a large specific capacity of 473.9 C g
- Published
- 2022
8. Self-Adapting Graphitic C6N6-Based Copper Single-Atom Catalyst for Smart Biosensors
- Author
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Qing Hong, Hong Yang, Yanfeng Fang, Wang Li, Caixia Zhu, Zhuang Wang, Sicheng Liang, Xuwen Cao, Zhixin Zhou, Yanfei Shen, Songqin Liu, and Yuanjian Zhang
- Abstract
Self-adaptability is highly envisioned for artificial devices such as robots with chemical noses. For this goal, seeking catalysts with multiple and modulable reaction pathways is promising but generally hampered by inconsistent reaction conditions. Herein, we report a self-adaptive CuSAC6N6 single-atom catalyst having two reactive oxygen-oriented pathways under the same reaction conditions. CuSAC6N6 consisted of coordinated peroxidase-like Cu-N coordination centers and photo-responsive donor-π-acceptor (D-π-A) units with promoted intramolecular charge separation and migration. Interestingly, it drove the basic oxidation of peroxidase substrates by the bound copper-oxo pathway, and undertook a second gain reaction triggered by light via the free hydroxyl radical pathway under the same conditions. A remarkable basic activity and a superb gain of up to 3.6 times under household lights were observed, significantly higher than that of its control systems, including solo carbon nitride-based nanozymes or photocatalysts, their mixtures, and even that under thermal stimuli to the maximum endured temperature for most lives. As an application, the self-adapting CuSAC6N6 was used to construct a glucose biosensor, which can intelligently switch the linear detection range and sensitivity to a diverse range of concentrations in vitro.
- Published
- 2022
9. Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil
- Author
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Desheng Ma, Chao Yang, Shengfei Zhang, Hong-Zhuang Wang, Xiuluan Li, Xinge Sun, Huajian Zhu, Junbo Xu, and Yishu Yan
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Materials science ,General Chemical Engineering ,Energy Engineering and Power Technology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Molecular dynamics ,Fuel Technology ,020401 chemical engineering ,Rheology ,Temperature dependence of liquid viscosity ,Chemical engineering ,Scientific method ,Heavy crude oil ,0204 chemical engineering ,0210 nano-technology - Abstract
Heavy oil, with high viscosity and complex compositions, often faces a series of challenges in the process of its exploitation and utilization. There are huge amounts of compositions with different...
- Published
- 2021
10. Mechanism of Metal Intercalation under Graphene through Small Vacancy Defects
- Author
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Xiaojie Liu, Michael C. Tringides, Ann Lii-Rosales, James W. Evans, Yong Han, Patricia A. Thiel, Cai-Zhuang Wang, and Yue Liu
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Materials science ,Graphene ,Intercalation (chemistry) ,Theoretical research ,02 engineering and technology ,Electronic structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Metal ,General Energy ,Chemical physics ,law ,visual_art ,Vacancy defect ,visual_art.visual_art_medium ,Physical and Theoretical Chemistry ,Defective graphene ,0210 nano-technology ,Mechanism (sociology) - Abstract
Metal intercalation under graphene has attracted extensive experimental and theoretical research because of its capability to manipulate the electronic structure and properties of graphene. However...
- Published
- 2021
11. Topochemical Deintercalation of Li from Layered LiNiB: toward 2D MBene
- Author
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Scott L. Carnahan, Kamila M. Wiaderek, Wenyu Huang, Gourab Bhaskar, Cai-Zhuang Wang, Maria Batuk, Kai-Ming Ho, Xun Wu, Yang Sun, Raquel A. Ribeiro, Julia V. Zaikina, Renhai Wang, Joke Hadermann, Paul C. Canfield, Chao Zhang, Volodymyr Gvozdetskyi, Aaron J. Rossini, and Sergey L. Bud'ko
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Chemistry ,Pair distribution function ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Crystallography ,Colloid and Surface Chemistry ,Solid-state nuclear magnetic resonance ,Lithium ,Boron - Abstract
The pursuit of two-dimensional (2D) borides, MBenes, has proven to be challenging, not the least because of the lack of a suitable precursor prone to the deintercalation. Here, we studied room-temperature topochemical deintercalation of lithium from the layered polymorphs of the LiNiB compound with a considerable amount of Li stored in between [NiB] layers (33 at. % Li). Deintercalation of Li leads to novel metastable borides (Li similar to 0.5NiB) with unique crystal structures. Partial removal of Li is accomplished by exposing the parent phases to air, water, or dilute HCl under ambient conditions. Scanning transmission electron microscopy and solid-state Li-7 and B-1(1) NMR spectroscopy, combined with X-ray pair distribution function (PDF) analysis and DFT calculations, were utilized to elucidate the novel structures of (Li similar to 0.5NiB) and the mechanism of Li-deintercalation. We have shown that the deintercalation of Li proceeds via a "zip-lock" mechanism, leading to the condensation of single [NiB] layers into double or triple layers bound via covalent bonds, resulting in structural fragments with Li[NiB](2) and Li[NiB](3) compositions. The crystal structure of Li similar to 0.5NiB is best described as an intergrowth of the ordered single [NiB], double [NiB](2), or triple [NiB](3) layers alternating with single Li layers; this explains its structural complexity. The formation of double or triple [NiB] layers induces a change in the magnetic behavior from temperature-independent paramagnets in the parent LiNiB compounds to the spin-glassiness in the deintercalated Li similar to 0.5NiB counterparts. LiNiB compounds showcase the potential to access a plethora of unique materials, including 2D MBenes (NiB).
- Published
- 2021
12. Correction to Machine Learning-Guided Discovery of Ternary Compounds Containing La, P, and Group 14 Elements
- Author
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Huaijun Sun, Chao Zhang, Weiyi Xia, Ling Tang, Renhai Wang, Georgiy Akopov, Nethmi W. Hewage, Kai-Ming Ho, Kirill Kovnir, and Cai-Zhuang Wang
- Subjects
Inorganic Chemistry ,Physical and Theoretical Chemistry - Published
- 2023
13. Crystallization of the P3Sn4 Phase upon Cooling P2Sn5 Liquid by Molecular Dynamics Simulation Using a Machine Learning Interatomic Potential
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Kai-Ming Ho, Yang Sun, Tongqi Wen, Chao Zhang, Haidi Wang, Feng Zhang, and Cai-Zhuang Wang
- Subjects
Materials science ,business.industry ,Interatomic potential ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Machine learning ,computer.software_genre ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Molecular dynamics ,General Energy ,law ,Phase (matter) ,Artificial intelligence ,Physical and Theoretical Chemistry ,Crystallization ,0210 nano-technology ,business ,computer - Abstract
We performed molecular dynamics simulations to study the crystallization of the P3Sn4 phase from P2Sn5 liquid using a machine learning (ML) interatomic potential with desirable efficiency and accur...
- Published
- 2021
14. Electronic Structure of Double-Layer Epitaxial Graphene on SiC(0001) Modified by Gd Intercalation
- Author
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Michael C. Tringides, Benjamin Schrunk, Myron Hupalo, Kai-Ming Ho, Cai-Zhuang Wang, Adam Kaminski, and Minsung Kim
- Subjects
Materials science ,Graphene ,Intercalation (chemistry) ,Fermi level ,02 engineering and technology ,Substrate (electronics) ,Electronic structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,symbols.namesake ,General Energy ,Adsorption ,law ,Chemical physics ,symbols ,Density functional theory ,Physical and Theoretical Chemistry ,0210 nano-technology ,Electronic band structure - Abstract
We systematically study the effects of Gd adsorption and intercalation on the electronic band structure of double-layer epitaxial graphene on Si-terminated SiC(0001) by first-principles calculations. We show that Gd adsorption and intercalation exhibit strong effects on the coupling between the graphene layers and between the buffer layer and substrate. Different adsorption/intercalation geometries can result in very different electron band structures. The number of Dirac cones and the positions of the Dirac cones relative to the Fermi level can be effectively manipulated through controlling the Gd adsorption/intercalation geometries. Our calculations provide useful insights to guide the experimental design of graphene-based materials with desirable functionalities for applications.
- Published
- 2020
15. Phase Diagram and Structure Map of Binary Nanoparticle Superlattices from a Lennard-Jones Model
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Alex Travesset, Yang Sun, Shang Ren, Cai-Zhuang Wang, Kai-Ming Ho, and Feng Zhang
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Condensed Matter - Materials Science ,Materials science ,Superlattice ,General Engineering ,Structure (category theory) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,Thermodynamics ,Binary number ,Nanoparticle ,Material Design ,Condensed Matter - Soft Condensed Matter ,Solvent evaporation ,Soft Condensed Matter (cond-mat.soft) ,General Materials Science ,Binary system ,Phase diagram - Abstract
A first principle prediction of the binary nanoparticle phase diagram assembled by solvent evaporation has eluded theoretical approaches. In this paper, we show that a binary system interacting through Lennard-Jones (LJ) potential contains all experimental phases in which nanoparticles are effectively described as quasi hard spheres. We report a phase diagram consisting of 53 equilibrium phases, whose stability is quite insensitive to the microscopic details of the potentials, thus giving rise to some type of universality. Furthermore, we show that binary lattices may be understood as consisting of certain particle clusters, i.e. motifs, which provide a generalization of the four conventional Frank-Kasper polyhedral units. Our results show that meta-stable phases share the very same motifs as equilibrium phases. We discuss the connection with packing models, phase diagrams with repulsive potentials and the prediction of likely experimental superlattices.
- Published
- 2020
16. Defect Interaction and Deformation in Graphene
- Author
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Hong-Xing Zhang, Wei Zhang, K. M. Ho, Minsung Kim, Cai-Zhuang Wang, Wen-Cai Lu, and Rong Cheng
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Materials science ,Condensed matter physics ,Graphene ,Lattice distortion ,02 engineering and technology ,Interaction energy ,Electron ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Elementary charge ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,General Energy ,law ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Interactions between defects in graphene and the lattice distortion and electronic charge localization induced by the defect interactions are studied by tight-binding (TB) calculations using the recently developed three-center TB potential model. The interaction between two 5–7 Stone–Wales defects gliding along the zig-zag (ZZ) direction of graphene, which has been observed by experiment, is studied at first to validate the TB calculations. Reconstructed divacancy defect pairs and di-adatom defect pairs separated along the glide ZZ and armchair (AC) directions in graphene, respectively, are then studied. We show that the characteristics (i.e., attractive or repulsive) and the strength of interactions between these defects are dependent on the type of defects and on the direction and distance of the defect separation on graphene. Although elastic interaction due to graphene lattice distortion induced by the defect has significant contribution to the total interaction energy, redistribution of electron char...
- Published
- 2020
17. From NaZn4Sb3 to HT-Na1–xZn4–ySb3: Panoramic Hydride Synthesis, Structural Diversity, and Thermoelectric Properties
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Tori Cox, Yang Sun, Julia V. Zaikina, Volodymyr Gvozdetskyi, Cai-Zhuang Wang, Sangki Hong, Feng Zhang, Kai-Ming Ho, Gourab Bhaskar, Bryan Owens-Baird, and Colin P. Harmer
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Materials science ,Hydride ,General Chemical Engineering ,Sodium ,chemistry.chemical_element ,General Chemistry ,Zinc ,Crystal structure ,Evaporation (deposition) ,Sodium hydride ,chemistry.chemical_compound ,Crystallography ,chemistry ,Thermoelectric effect ,Materials Chemistry ,Monoclinic crystal system - Abstract
Two new sodium zinc antimonides NaZn4Sb3 and HT-Na1–xZn4–ySb3 were synthesized by using reactive sodium hydride, NaH, as a precursor. The hydride route provides uniform mixing and comprehensive control over the composition, facilitating fast reactions and high-purity samples, whereas traditional synthesis using sodium metal results in inhomogeneous samples with a significant fraction of the more stable NaZnSb compound. NaZn4Sb3 crystallizes in the hexagonal P63/mmc space group (No. 194, Z = 2, a = 4.43579(4) A, c = 23.41553(9) A) and is stable upon heating in vacuum up to 736 K. The layered crystal structure of NaZn4Sb3 is related to the structure of the well-studied thermoelectric antimonides AeZn2Sb2 (Ae = Ca, Sr, Eu). Upon heating in vacuum, NaZn4Sb3 transforms to HT-Na1–xZn4–ySb3 (x = 0.047(3), y = 0.135(1)) due to partial Na/Zn evaporation/elimination, as was determined from high-temperature in situ synchrotron powder X-ray diffraction. HT-Na1–xZn4–ySb3 has a complex monoclinic structure with conside...
- Published
- 2019
18. Tailored Plasmons in Pentacene/Graphene Heterostructures with Interlayer Electron Transfer
- Author
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Cai-Zhuang Wang, Yongheng Zhang, Zhe Fei, Yilong Luan, Xin Wang, Yi Shi, Minsung Kim, Kai-Ming Ho, and Fengrui Hu
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Materials science ,FOS: Physical sciences ,Bioengineering ,02 engineering and technology ,law.invention ,Pentacene ,Electron transfer ,symbols.namesake ,chemistry.chemical_compound ,law ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,General Materials Science ,Plasmon ,Condensed Matter - Mesoscale and Nanoscale Physics ,business.industry ,Graphene ,Mechanical Engineering ,Heterojunction ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,chemistry ,symbols ,Optoelectronics ,van der Waals force ,0210 nano-technology ,business ,Physics - Optics ,Optics (physics.optics) - Abstract
Van der Waals (vdW) heterostructures, which are produced by the precise assemblies of varieties of two-dimensional (2D) materials, have demonstrated many novel properties and functionalities. Here we report a nano-plasmonic study of vdW heterostructures that were produced by depositing ordered molecular layers of pentacene on top of graphene. We find through nano-infrared (IR) imaging that surface plasmons formed due to the collective oscillations of Dirac fermions in graphene are highly sensitive to the adjacent pentacene layers. In particular, the plasmon wavelength declines systematically but nonlinearly with increasing pentacene thickness. Further analysis and density functional theory (DFT) calculations indicate that the observed peculiar thickness dependence is mainly due to the tunneling-type electron transfer from pentacene to graphene. Our work unveils a new method for tailoring graphene plasmons and deepens our understanding of the intriguing nano-optical phenomena due to interlayer couplings in novel vdW heterostructures., Comment: 21 pages
- Published
- 2019
19. Selenium Edge as a Selective Anchoring Site for Lithium–Sulfur Batteries with MoSe2/Graphene-Based Cathodes
- Author
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Zhengtang Luo, Hoilun Wong, Hwanbin Lee, Hongwei Liu, Xuewu Ou, Minghao Zhuang, Cai-Zhuang Wang, Yuting Cai, Delowar Hossain, and Zhenjing Liu
- Subjects
Materials science ,Diffusion barrier ,Graphene ,Oxide ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,X-ray photoelectron spectroscopy ,Chemical engineering ,law ,General Materials Science ,Lithium ,0210 nano-technology ,Dissolution ,Polysulfide - Abstract
For lithium-sulfur batteries (LSBs), the dissolution of lithium polysulfide and the consequent "shuttle effect" remain major obstacles for their practical applications. In this study, we designed a new cathode material comprising MoSe2/graphene to selectively adsorb polysulfides on the selenium edges and thus to mitigate their dissolution. More specifically, few-layered MoSe2 was first grown on nitrogen-doped reduced graphene oxide (N-rGO) using the chemical vapor deposition method and then infiltrated with sulfur as the cathode for LSBs. An initial capacity of 1028 mA h g-1 was achieved for S/MoSe2/N-rGO at 0.2 C, higher than 981 and 405.1 mA h g-1 for pure graphene and sulfur, respectively, along with enhanced cycling durability and rate capability. Moreover, the density functional theory simulation, in addition to the experimental adsorption test, X-ray photoelectron spectroscopy analysis, and transmission electron microscopy technique, reveals the dual roles that MoSe2 plays in improving the performance of LSBs by functioning as the binding sites for lithium polysulfides and as the platform that enables fast Li-ion diffusion by reducing its diffusion barrier. The reported finding suggests that the transition-metal selenides could be an efficient alternative material as the cathode for LSBs.
- Published
- 2019
20. One-Step Polyoxometalates-Assisted Synthesis of Manganese Dioxide for Asymmetric Supercapacitors with Enhanced Cycling Lifespan
- Author
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Debao Xiao, Zhuang Wang, Deling Yuan, Jianmin Gu, Guang Cong Zhang, Xiaoyong Fan, Jinling Zhong, Shoufeng Tang, and Siheng Li
- Subjects
Supercapacitor ,Materials science ,Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Manganese ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Capacitance ,0104 chemical sciences ,law.invention ,Capacitor ,Transition metal ,chemistry ,Chemical engineering ,law ,Environmental Chemistry ,Specific energy ,0210 nano-technology - Abstract
Transition metal oxides have attracted a lot of interest for the high energy density in asymmetric supercapacitors, but the fast capacity fading, low electrical conductivity and hard clean industrialization still limit the practical applications. In order to overcome the challenge, a novel type of polyoxometalate-assisted hydrothermal strategy for the synthesis of manganese dioxide as an example for asymmetric supercapacitors is reported. The samples are prepared in one step fashion, avoiding complicated equipment and acid corrosion process simultaneously, which are fully researched the morphology, chemical components and the surface area thereby finding its impact on electrochemical performance. Results in electrochemical test demonstrate that the α-MnO2 have good capacitance (235 F g–1) in neutral electrolytes. The asymmetric capacitors assembled by manganese dioxide and activated carbon (AC) as electrode materials possessed large specific energy (27.6 Wh kg–1 at 200 W kg–1 and 19.4 Wh kg–1 at 5000 W kg...
- Published
- 2018
21. Fundamental Link between β Relaxation, Excess Wings, and Cage-Breaking in Metallic Glasses
- Author
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Feng Zhang, Yang Sun, Ranko Richert, Menghao Yang, Konrad Samwer, Haibin Yu, Cai-Zhuang Wang, Jian-Bo Liu, and Kai-Ming Ho
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Amorphous metal ,Materials science ,02 engineering and technology ,Link (geometry) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Microsecond ,Chemical physics ,0103 physical sciences ,Relaxation (physics) ,General Materials Science ,Physical and Theoretical Chemistry ,010306 general physics ,0210 nano-technology - Abstract
In glassy materials, the Johari-Goldstein secondary (β) relaxation is crucial to many properties as it is directly related to local atomic motions. However, a long-standing puzzle remains elusive: why some glasses exhibit β relaxations as pronounced peaks while others present as unobvious excess wings? Using microsecond atomistic simulation of two model metallic glasses (MGs), we demonstrate that such a difference is associated with the number of string-like collective atomic jumps. Relative to that of excess wings, we find that MGs having pronounced β relaxations contain larger numbers of such jumps. Structurally, they are promoted by the higher tendency of cage-breaking events of their neighbors. Our results provide atomistic insights for different signatures of the β relaxation that could be helpful for understanding the low-temperature dynamics and properties of MGs.
- Published
- 2018
22. Formation of Multilayer Cu Islands Embedded beneath the Surface of Graphite: Characterization and Fundamental Insights
- Author
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Patricia A. Thiel, Michael C. Tringides, Yinghui Zhou, Yong Han, James W. Evans, Cai-Zhuang Wang, Minsung Kim, Dapeng Jing, and Ann Lii-Rosales
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Materials science ,Intercalation (chemistry) ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Overlayer ,General Energy ,Chemical engineering ,X-ray photoelectron spectroscopy ,law ,Physical vapor deposition ,Deposition (phase transition) ,Graphite ,Physical and Theoretical Chemistry ,Scanning tunneling microscope ,0210 nano-technology - Abstract
We present an extensive experimental study of the conditions under which Cu forms encapsulated islands under the top surface layers of graphite, as a result of physical vapor deposition of Cu on argon-ion-bombarded graphite. When the substrate is held at 800 K during deposition, conditions are optimal for formation of encapsulated multilayer Cu islands. Deposition temperatures below 600 K favor adsorbed Cu clusters, while deposition temperatures above 800 K favor a different type of feature that is probably a single-layer intercalated Cu island. The multilayer Cu islands are characterized with respect to size and shape, thickness and continuity of the graphitic overlayer, relationship to graphite steps, and stability in air. The experimental techniques are scanning tunneling microscopy and X-ray photoelectron spectroscopy. We also present an extensive study using density functional theory to compare stabilities of a wide variety of configurations of Cu atoms, Cu clusters, and Cu layers on/under the graphi...
- Published
- 2018
23. Ternary Bismuthide SrPtBi2: Computation and Experiment in Synergism to Explore Solid-State Materials
- Author
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Zuzanna Sobczak, Tomasz Klimczuk, Xin Gui, Cai-Zhuang Wang, Weiwei Xie, Kai-Ming Ho, and Xin Zhao
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Materials science ,Thermodynamics ,Crystal structure ,010402 general chemistry ,01 natural sciences ,Bismuthide ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Pearson symbol ,chemistry.chemical_compound ,Tetragonal crystal system ,General Energy ,chemistry ,Ternary compound ,0103 physical sciences ,Orthorhombic crystal system ,Physical and Theoretical Chemistry ,010306 general physics ,Ternary operation ,Stoichiometry - Abstract
A combination of theoretical calculation and the experimental synthesis to explore the new ternary compound is demonstrated in the Sr–Pt–Bi system. Because Pt–Bi is considered as a new critical charge-transfer pair for superconductivity, it inspired us to investigate the Sr–Pt–Bi system. With a thorough calculation of all the known stable/metastable compounds in the Sr–Pt–Bi system and crystal structure predictions, the thermodynamic stability of hypothetical stoichiometry, SrPtBi2, is determined. Following the high-temperature synthesis and crystallographic analysis, the first ternary bismuthide in Sr–Pt–Bi, SrPtBi2 was prepared, and the stoichiometry was confirmed experimentally. SrPtBi2 crystallizes in the space group Pnma (S.G. 62, Pearson Symbol oP48), which matches well with theoretical prediction using an adaptive genetic algorithm. Using first-principles calculations, we demonstrate that the orthorhombic structure has lower formation energies than other 112 structure types, such as tetragonal BaMn...
- Published
- 2018
24. Fe-Cluster Compounds of Chalcogenides: Candidates for Rare-Earth-Free Permanent Magnet and Magnetic Nodal-Line Topological Material
- Author
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Cai-Zhuang Wang, Kai-Ming Ho, Minsung Kim, and Xin Zhao
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Chemistry ,Enthalpy ,02 engineering and technology ,Crystal structure ,021001 nanoscience & nanotechnology ,Topology ,01 natural sciences ,Inorganic Chemistry ,Magnetization ,Chalcogen ,Magnet ,0103 physical sciences ,Vertex (curve) ,Cluster (physics) ,Physical and Theoretical Chemistry ,010306 general physics ,0210 nano-technology ,Line (formation) - Abstract
Fe-cluster-based crystal structures are predicted for chalcogenides Fe3X4 (X = S, Se, Te) using an adaptive genetic algorithm. Topologically different from the well-studied layered structures of iron chalcogenides, the newly predicted structures consist of Fe clusters that are either separated by the chalcogen atoms or connected via sharing of the vertex Fe atoms. Using first-principles calculations, we demonstrate that these structures have competitive or even lower formation energies than the experimentally synthesized Fe3X4 compounds and exhibit interesting magnetic and electronic properties. In particular, we show that Fe3Te4 can be a good candidate as a rare-earth-free permanent magnet and Fe3S4 can be a magnetic nodal-line topological material.
- Published
- 2017
25. Theoretical Prediction of Si2–Si33 Absorption Spectra
- Author
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Kai-Ming Ho, Cai-Zhuang Wang, Qing-Jun Zang, Li-Zhen Zhao, Wei Qin, and Wen-Cai Lu
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Absorption spectroscopy ,Extended X-ray absorption fine structure ,Infrared ,Chemistry ,Doping ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,medicine.disease_cause ,01 natural sciences ,Two-photon absorption ,0104 chemical sciences ,medicine ,Density functional theory ,Physical and Theoretical Chemistry ,Atomic physics ,0210 nano-technology ,Absorption (electromagnetic radiation) ,Ultraviolet - Abstract
The optical absorption spectra of Si2–Si33 clusters were systematically studied by a time-dependent density functional theory approach. The calculations revealed that the absorption spectrum becomes significantly broad with increasing cluster size, stretching from ultraviolet to the infrared region. The absorption spectra are closely related to the structural motifs. With increasing cluster size, the absorption intensity of cage structures gradually increases, but the absorption curves of the prolate and the Y-shaped structures are very sensitive to cluster size. If the transition energy reaches ∼12 eV, it is noted that all the clusters have remarkable absorption in deep ultraviolet region of 100–200 nm, and the maximum absorption intensity is ∼100 times that in the visible region. Further, the optical responses to doping in the Si clusters were studied.
- Published
- 2017
26. Role of Surface Stress on the Reactivity of Anatase TiO2(001)
- Author
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Jin Zhao, Manh Cuong Nguyen, Cai-Zhuang Wang, Wissam A. Saidi, Kai-Ming Ho, Huijuan Sun, Jinlong Yang, and Yongliang Shi
- Subjects
Inert ,Surface (mathematics) ,Anatase ,Materials science ,Passivation ,Surface stress ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Stress (mechanics) ,Adsorption ,Chemical physics ,General Materials Science ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
In contrast with theoretical predictions in which anatase TiO2(001) and its (1 × 4) reconstructed surfaces are highly reactive, recent experimental results show this surface to be inert except for the defect sites. In this report, based on a systematic study of anatase TiO2(001)-(1 × 4) surface using first-principles calculations, the tensile stress is shown to play a crucial role on the surface reactivity. The predicted high reactivity based on add-molecule model is due to the large surface tensile stress, which can be easily suppressed by a stress-release mechanism. We show that various surface defects can induce stress release concomitantly with surface passivation. Thus the synthesis of anatase(001) surface with few defects is essential to improve the reactivity, which can be achieved, for example, via H2O adsorption. Our study provides a uniform interpretation of controversial experimental observations and theoretical predictions on anatase TiO2(001) surface and further proposes new insights into the...
- Published
- 2017
27. Correlation Matrix Renormalization Theory: Improving Accuracy with Two-Electron Density-Matrix Sum Rules
- Author
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Chang Liu, Jun Liu, Yongxin Yao, Kai-Ming Ho, Ping Wu, and Cai-Zhuang Wang
- Subjects
Physics ,Electron density ,Electronic correlation ,Covariance matrix ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Computer Science Applications ,Renormalization ,Matrix (mathematics) ,Quantum mechanics ,0103 physical sciences ,Benchmark (computing) ,Statistical physics ,Physical and Theoretical Chemistry ,010306 general physics ,0210 nano-technology ,Ground state ,Wave function - Abstract
We recently proposed the correlation matrix renormalization (CMR) theory to treat the electronic correlation effects [Phys. Rev. B 2014, 89, 045131 and Sci. Rep. 2015, 5, 13478] in ground state total energy calculations of molecular systems using the Gutzwiller variational wave function (GWF). By adopting a number of approximations, the computational effort of the CMR can be reduced to a level similar to Hartree-Fock calculations. This paper reports our recent progress in minimizing the error originating from some of these approximations. We introduce a novel sum-rule correction to obtain a more accurate description of the intersite electron correlation effects in total energy calculations. Benchmark calculations are performed on a set of molecules to show the reasonable accuracy of the method.
- Published
- 2016
28. Effects of Oxygen Impurities on Glass-Formation Ability in Zr2Cu Alloy
- Author
-
F. Dong, Zhanyu Wang, Matthew J. Kramer, G.Q. Yue, Rong-Jun Zhang, Cai-Zhuang Wang, B. Shen, Liang-Yao Chen, Li Huang, Kai-Ming Ho, Songyou Wang, and Yu-Xiang Zheng
- Subjects
010302 applied physics ,Icosahedral symmetry ,Alloy ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Oxygen ,Surfaces, Coatings and Films ,Ab initio molecular dynamics ,Crystallography ,Octahedron ,chemistry ,Impurity ,0103 physical sciences ,Materials Chemistry ,engineering ,Physical and Theoretical Chemistry ,Oxygen impurity ,0210 nano-technology ,Volume concentration - Abstract
Using ab initio molecular dynamics simulations, we show that oxygen (O) impurities have a noticeable influence on the glass-formation ability (GFA) in Zr2Cu alloy. Cu-centered icosahedral clusters and Zr-centered Kasper polyhedra are the dominate short-range orders in undercooled Zr2Cu liquid which are most likely to be responsible for the glass formation in Zr2Cu systems. When O is introduced, a Zr octahedron is formed around the O impurity. Most of the Zr atoms in the octahedron also serve as the bridging atoms for cross-linked Kasper polyhedral network, resulting in an O-centered medium range order (MRO) structure. Meanwhile, Cu atoms are moved away from the first shell of O-centered octahedral clusters. With 1 at. % O impurities, the fractions of Zr-centered clusters are less affected, while the increase of ideal icosahedral order and decrease of distorted icosahedral order lead to a more stable atomic structure. This result suggests that a low concentration of O impurities would improve the GFA in Zr2Cu alloy. However, when ∼5 at. % O impurities are included, the ideal icosahedral clusters and Zr-centered Kasper polyhedra are seriously suppressed by the formation of O-centered MRO, which can lead to deterioration of GFA. Our analyses provide useful insight into glass formation behavior in O-doped metallic alloy systems.
- Published
- 2016
29. Zero-Strain Na2FeSiO4 as Novel Cathode Material for Sodium-Ion Batteries
- Author
-
Jinxiao Mi, Zhuo Ye, Kai-Ming Ho, Yong Yang, Xin Zhao, Zhengliang Gong, Jianghuai Guo, Matthew J. McDonald, Shunqing Wu, Zi-Zhong Zhu, Shouding Li, and Cai-Zhuang Wang
- Subjects
Materials science ,Strain (chemistry) ,Sodium ,Cell volume ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Open framework ,Cathode ,Silicate ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Cathode material ,General Materials Science ,0210 nano-technology - Abstract
A new cubic polymorph of sodium iron silicate, Na2FeSiO4, is reported for the first time as a cathode material for Na-ion batteries. It adopts an unprecedented cubic rigid tetrahedral open framework structure, i.e., F4̅3m, leading to a polyanion cathode material without apparent cell volume change during the charge/discharge processes. This cathode shows a reversible capacity of 106 mAh g(-1) and a capacity retention of 96% at 5 mA g(-1) after 20 cycles.
- Published
- 2016
30. Magnetic Moment Enhancement for Mn7 Cluster on Graphene
- Author
-
Xiaojie Liu, Hai-Qing Lin, Kai-Ming Ho, and Cai-Zhuang Wang
- Subjects
Coupling ,Materials science ,Magnetic moment ,Condensed matter physics ,Graphene ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Electron transfer ,General Energy ,law ,Ferrimagnetism ,Cluster (physics) ,Physical and Theoretical Chemistry - Abstract
Mn7 cluster on graphene with different structural motifs and magnetic orders are investigated systematically by first-principles calculations. The calculations show that Mn7 on graphene prefers a two-layer motif and exhibits a ferrimagnetic coupling. The magnetic moment of the Mn7 cluster increases from 5.0 μB at its free-standing state to about 6.0 μB upon adsorption on graphene. Mn7 cluster also induces about 0.3 μB of magnetic moment in the graphene layer, leading to an overall enhancement of 1.3 μB magnetic moment for Mn7 on graphene. Detail electron transfer and bonding analysis have been carried out to investigate the origin of the magnetic enhancement.
- Published
- 2014
31. Ultrafast Bulk Diffusion of AlHx in High-Entropy Dehydrogenation Intermediates of NaAlH4
- Author
-
Brandon C. Wood, Mei-Yin Chou, Feng Zhang, Cai-Zhuang Wang, Kai-Ming Ho, and Yan Wang
- Subjects
Hydrogen ,Chemistry ,chemistry.chemical_element ,Decomposition ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Molecular dynamics ,General Energy ,Chemical physics ,Picosecond ,Physical chemistry ,Dehydrogenation ,Physical and Theoretical Chemistry ,Diffusion (business) ,Ultrashort pulse - Abstract
Using first-principles molecular dynamics (FPMD) and total-energy calculations, we demonstrate low-barrier bulk diffusion of Al-bearing species in γ-NaAlH4, a recently proposed high-entropy polymorph of NaAlH4. For charged AlH4– and neutral AlH3 vacancies, the computed barriers for diffusion are
- Published
- 2014
32. Interface Structure Prediction from First-Principles
- Author
-
Min Ji, Qiang Shu, Hongjun Xiang, Manh Cuong Nguyen, Yangang Wang, Xingao Gong, Cai-Zhuang Wang, Kai-Ming Ho, and Xin Zhao
- Subjects
Structure (mathematical logic) ,General Energy ,Materials science ,Interface (Java) ,Nanotechnology ,Physical and Theoretical Chemistry ,ComputingMethodologies_COMPUTERGRAPHICS ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
Information about the atomic structures at solid–solid interfaces is crucial for understanding and predicting the performance of materials. Due to the complexity of the interfaces, it is very chall...
- Published
- 2014
33. Effect of Fatty Acids on Interfacial Tensions of Novel Sulfobetaines Solutions
- Author
-
Hongyan Cai, Qun Zhang, Hong-Zhuang Wang, Lei Zhang, Yan Liu, Maozhang Tian, Fan Zhang, Lu Zhang, Zi-Yu Liu, and Zhao-Hui Zhou
- Subjects
chemistry.chemical_classification ,Chemistry ,General Chemical Engineering ,Drop (liquid) ,Energy Engineering and Power Technology ,Chain length ,chemistry.chemical_compound ,Fuel Technology ,Adsorption ,Betaine ,Oil phase ,Organic chemistry ,Molecule ,sense organs ,Carbon number ,Alkyl - Abstract
The dynamic interfacial tensions (IFTs) of two zwitterionic surfactants with different hydrophobic groups, alkyl sulfobetaine (ASB) and benzyl substituted alkyl sulfobetaine (BSB), against hydrocarbons, acidic model oils containing fatty acids, and three crude oils have been investigated by a spinning drop interfacial tensiometer. The influences of concentration and alkyl chain length of fatty acids on the IFTs of two betaine solutions were expounded. The effect of the alkyl chain carbon number (ACN) of the oil phase on the IFTs has also been researched. The experimental results show that the whole hydrophilic part of the betaine molecule (anionic-cationic part and the hydroxyl) is almost flat at the interface, which results in the larger occupied space of the hydrophilic part at the interface. Therefore, the branched and benzyl-substituted betaine, BSB, has a larger sized hydrophobic part and can form a more compact adsorption film than linear ASB molecules. The IFT values decrease obviously when fatty a...
- Published
- 2014
34. Strain Effects in Ge/Si and Si/Ge Core/Shell Nanowires
- Author
-
Nuo Liu, Yan-Rong Li, Kai-Ming Ho, Cai-Zhuang Wang, Yongxin Yao, and Ning Lu
- Subjects
Materials science ,Condensed matter physics ,Strain (chemistry) ,Band gap ,Nanowire ,Shell (structure) ,Nanotechnology ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Core shell ,Core (optical fiber) ,General Energy ,Density of states ,Density functional theory ,Physical and Theoretical Chemistry - Abstract
Strain-dependent electronic properties of [112] Ge/Si and Si/Ge core/shell nanowires are studied using first-principles calculations within density functional theory. We show that the transition from indirect to quasidirect gap can be obtained by applying compressive strain and the width of the band gap can be tuned by strain. The analysis of the projected density of states indicates that the quasidirect gap is strongly influenced by the atoms in the {111} facets. Several possible applications have been discussed based on their distinguished electronic properties.
- Published
- 2011
35. Size- and Strain-Dependent Electronic Structures in H-Passivated Si [112] Nanowires
- Author
-
Jia-An Yan, Cai-Zhuang Wang, Mei-Yin Chou, Kai-Ming Ho, Ning Lu, and Li Huang
- Subjects
Materials science ,Condensed matter physics ,Strain (chemistry) ,Band gap ,Nanowire ,Nanotechnology ,Aspect ratio (image) ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,Compressive strength ,Density functional theory ,Direct and indirect band gaps ,Physical and Theoretical Chemistry ,Electronic band structure - Abstract
Using first-principles calculations within density functional theory, we have investigated the electronic properties of H-passivated Si nanowires (SiNWs) oriented along the 112 direction, with the atomic geometries retrieved via global search using genetic algorithm. We show that [112] SiNWs have an indirect band gap in the ultrathin diameter regime, whereas the energy difference between the direct and indirect fundamental band gaps progressively decreases as the wire size increases, indicating that larger [112] SiNWs could have a quasi-direct band gap. We further show that this quasi-direct gap feature can be enhanced when applying uniaxial compressive stress along the wire axis. Moreover, our calculated results also reveal that the electronic band structure is sensitive to the change of the aspect ratio of the cross sections.
- Published
- 2008
36. Comparison of the Growth Patterns of Sin and Gen Clusters (n = 25−33)
- Author
-
Li-Zhen Zhao, Kai-Ming Ho, Wen-Cai Lu, Cai-Zhuang Wang, and Wei Qin
- Subjects
Crystallography ,Chemistry ,Cluster (physics) ,Density functional theory ,Prolate spheroid ,Physical and Theoretical Chemistry - Abstract
We performed an unbiased search for low-energy structures of medium-sized neutral Si n and Ge n clusters (n = 25-33) using a genetic algorithm (GA) coupled with tight-binding interatomic potentials. Structural candidates obtained from our GA search were further optimized by first-principles calculations using density functional theory (DFT). Our approach reproduces well the lowest-energy structures of Si n and Ge n clusters of n = 25-29 compared to previous studies, showing the accuracy and reliability of our approach. In the present study, we pay more attention to determine low-lying isomers of Si n and Ge n (n = 29-33) and study the growth patterns of these clusters. The B3LYP calculations suggest that the growth pattern of Si n (n = 25-33) clusters undergoes a transition from prolate to cage at n = 31, while this transition appears at n = 26 from the PBE-calculated results. In the size range of 25-33, the corresponding Ge n clusters hold the prolate growth pattern. The relative stabilities and different structural motifs of Si n and Ge n (n = 25-33) clusters were studied, and the changes of small cluster structures, when acting as building blocks of large clusters, were also discussed.
- Published
- 2008
37. Evolution of Toxicity upon Hydrolysis of Fenoxaprop-p-ethyl
- Author
-
De-Gao Wang, Jingwen Chen, Xianliang Qiao, Jing Lin, Zhuang Wang, Liping Huang, and Xiyun Cai
- Subjects
Time Factors ,biology ,Degradation kinetics ,Herbicides ,Stereochemistry ,Hydrolysis ,Daphnia magna ,General Chemistry ,biology.organism_classification ,Daphnia ,Aqueous buffer ,Toxicity ,Animals ,Propionates ,General Agricultural and Biological Sciences ,Oxazoles ,Water Pollutants, Chemical ,Nuclear chemistry - Abstract
Hydrolysis of fenoxaprop-p-ethyl (FE), a widely used herbicide, was studied in aqueous buffer solutions at pH ranging from 4.0 to 10.0. The degradation kinetics, strongly dependent on pH values, followed first-order kinetics. FE was relatively stable in neutral media, whereas it degraded rapidly with decreasing or increasing pH. In acidic conditions (pH = 4, 5), the benzoxazolyl-oxy-phenyl ether linkage of FE was cleaved to form ethyl 2-(4-hydroxyphenoxy)propanoate (EHPP) and 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB). While in basic conditions (pH = 8, 9, 10), herbicidal activity fenoxaprop-p (FA) was formed via breakdown of the ester bond of the herbicide. Both the two pathways were concurrent in neutral conditions (pH = 6, 7). Toxicity studies on Daphnia magna showed that FE was most toxic to D. magna with 48 h EC(50) of 14.3 micromol/L, followed by FA (43.8 micromol/L), CDHB (49.8 micromol/L), and EHPP (333.1 micromol/L). Mode of toxic action analysis indicated that EHPP exhibited toxicity via polar narcosis, whereas CDHB belonged to reactive acing compound. The mixture toxicity of CDHB and EHPP was nonadditive and can be predicted by a response addition model. Therefore, the evaluation of overall FE toxicity to D. magna in the aquatic systems needs to consider the degradation of FE.
- Published
- 2007
38. The Structure of Ultrathin H-Passivated [112] Silicon Nanowires
- Author
-
Tzu-Liang Chan, Kai-Ming Ho, Cristian V. Ciobanu, Feng-Chuan Chuang, Cai-Zhuang Wang, and Ning Lu
- Subjects
Materials science ,Hydrogen ,Ab initio ,Nanowire ,chemistry.chemical_element ,Molecular physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Crystallography ,General Energy ,chemistry ,Density functional theory ,Physical and Theoretical Chemistry ,Silicon nanowires - Abstract
We report on the atomic structure and energetics of H-passivated silicon nanowires that are oriented along the [112] crystallographic direction and have effective diameters of approximately 1 nm and below. Using a genetic algorithm structural optimization followed by ab initio density functional theory calculations, we find that at certain values of the hydrogen chemical potential the nanowires can take relatively stable (magic) structures with rectangular cross sections bounded by monohydride {110} and {111} facets with dihydride wire edges. Variations in the chemical potential of hydrogen alter the wire structures retrieved by the optimization, the most prominent example of this being that the {111} nanofacets acquire trihydride terminations instead of monohydride ones when the H chemical potential is raised. While the trihydride-passivated wires have already been experimentally observed, the magic-number monohydride-facetted wires found here may serve as useful predictions to be tested in the future.
- Published
- 2007
39. Potential Energy Surfaces of SimOn Cluster Formation and Isomerization
- Author
-
W. C. Lu, Kai-Ming Ho, Mark S. Gordon, Ivana Adamovic, Pavel V. Avramov, and Cai-Zhuang Wang
- Subjects
Coupled cluster ,Chemistry ,Cluster (physics) ,Singlet state ,Physical and Theoretical Chemistry ,Atomic physics ,Potential energy ,Molecular physics ,Isomerization ,Transition state ,Basis set ,Nanoclusters - Abstract
The reaction paths for formation and isomerization of a set of silica Si m O n (m = 2,3, n = 1-5) nanoclusters have been investigated using second-order pertubation theory (MP2) with the 6-31G(d) basis set. The MP2/ 6-31G(d) calculations have predicted singlet ground states for all clusters excluding Si 3 O 2 . The total energies of the most important points on the potential energy surfaces (PES) have been determined using the completely renormalized (CR) singles and doubles coupled cluster method including perturbative triples, CR-CCSD(T) with the cc-pVTZ basis set. Although transition states have been located for many isomerization reactions, only for Si 3 O 3 and Si 3 O 4 have some transition states been found for the formation of a cluster from the separated reactants. In all other cases, the process of formation of Si m O n clusters appears to proceed without potential energy barriers.
- Published
- 2005
40. Structures and Fragmentations of Small Silicon Oxide Clusters by ab Initio Calculations
- Author
-
W. C. Lu, Mark S. Gordon, Kai-Ming Ho, Van Du Nguyen, Michael W. Schmidt, and Cai-Zhuang Wang
- Subjects
Fragmentation (mass spectrometry) ,Ab initio quantum chemistry methods ,Chemistry ,Physics::Atomic and Molecular Clusters ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Silicon oxide ,Ground state ,Molecular physics ,Bond-dissociation energy ,Dissociation (chemistry) - Abstract
The structures, energies, and fragmentation stabilities of silicon oxide clusters SimOn, with m = 1−5, n = 1, 2m + 1, are studied systematically by ab initio calculations. New structures for nine clusters are found to be energetically more favorable than previously proposed structures. Using the ground state structures and energies obtained from our calculations, we have also studied fragmentation pathways and dissociation energies of the clusters. Our computational results show that the dissociation energy is strongly correlated with the O/Si ratio. Oxygen-rich clusters tend to have larger dissociation energies, as well as larger HOMO−LUMO gaps. Our calculations also show that SiO is the most abundant species in the fragmentation products.
- Published
- 2003
41. Tight-binding molecular-dynamics simulation of buckyball collisions
- Author
-
BL Zhang, K.M. Ho, Cai-Zhuang Wang, and Che Ting Chan
- Subjects
Fusion ,Molecular dynamics ,Tight binding ,Fullerene ,Chemical bond ,Fragmentation (mass spectrometry) ,Chemistry ,General Engineering ,Molecule ,Physical and Theoretical Chemistry ,Atomic physics ,Nuclear Experiment ,Collision - Abstract
The collisions between C[sub 60] molecules are studied by tight-binding molecular-dynamics simulations. We observe three different regimes of behavior as the collisions become more and more energetic: bouncing, fusion, and fragmentation. The critical energies for fusion and fragmentation as well as details of the energy transfer during the collision process for the bouncing regime are investigated. The collisions at several specific energies and orientations produce interesting novel molecules, such as small baby cages, caps, and even a Russian-Doll molecule in which a small cage is trapped in a bigger one. 28 refs., 5 figs., 2 tabs.
- Published
- 1993
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