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1. Promising porous carbons derived from lotus seedpods with outstanding supercapacitance performance | |||
LIU Bei,ZHOU Xiahong,CHEN Hongbiao,LIU Yijiang,LI Huaming | |||
Chemistry 08 April 2016 | |||
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Abstract:Biomass-derived porous carbons are widely regarded as one of the most promising electrode materials for supercapacitors owing to their natural abundance and low-cost. Herein, we present a facile approach to synthesize promising porous carbons via a two-step fabrication process using lotus seedpods (LS) as the biomass precursor. Firstly, the LS is hydrothermally treated in a KOH aqueous solution. After filtration and drying, the hydrothermal product is directly subjected to simultaneous pyrolysis and activation, giving LS-derived porous carbon materials. The morphology, structure and textural properties of the carbon materials are investigated by scanning electron microscopy, transmission electron microscopy, and N2 sorption isotherms. The porous carbon prepared under optimal conditions exhibits a relatively high BET surface area of 1813 m2 g-1 and an average pore size of 3.30 nm. Such porous carbon shows outstanding capacitive performance (402 F g-1 at 0.5 A g-1), good rate capability and excellent cycling stability (95.4% of capacitance retention after 10,000 cycles) in 6 M KOH electrolyte. More importantly, the as-assembled symmetric supercapacitor delivers a high energy density of 12.5 Wh kg-1 at power density of 260 W kg-1. | |||
TO cite this article:LIU Bei,ZHOU Xiahong,CHEN Hongbiao, et al. Promising porous carbons derived from lotus seedpods with outstanding supercapacitance performance[OL].[ 8 April 2016] http://en.paper.edu.cn/en_releasepaper/content/4683049 |
2. Analytical expressions for interaction between two palnar and sperical surface for 2-1type asymmetric electrolytes at positive surface potential | |||
LIU Guozhi | |||
Chemistry 15 March 2016 | |||
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Abstract:In this paper, we suggest an analytical solution to Poisson-Boltzmann equation for the calculation of potential distributions between two identical plate colloidal particles immersed in a 2:1 type electrolyte solution with constant high or medium surface potential. Our expression fits well to the exact values of the potential between two parallel plates. Numerical results indicate that this analytical solution provides accurate description for the dimensionless distance ≤ 3. The suggested solution can be successfully applied in calculating the potential for identical plates with high or medium surface potentials. A simple analysis expression for the energy of interactions between two identical plates with constantly high or medium surface potential is given. The solutions in analytical and numerical forms become indistinguishable when , and , respectively. When , , the approximate solution is in close agreement with the numerical solution. By use of accurate analytical expression for the corresponding interaction energy between two parallel similar plates obtained presently, a simple analysis expression is given for calculating the energy of interactions between two identical spherical colloidal particles in a 2:1 type electrolyte solution with the help of Derjaguin's approximation. | |||
TO cite this article:LIU Guozhi. Analytical expressions for interaction between two palnar and sperical surface for 2-1type asymmetric electrolytes at positive surface potential[OL].[15 March 2016] http://en.paper.edu.cn/en_releasepaper/content/4680941 |
3. Dendritic NiCu nanopearl chains for electrocatalytic production of hydrogen in acidic media | |||
LIU Lu,HE Jianbo | |||
Chemistry 15 February 2016 | |||
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Abstract:Dendritic NiCu nanopearl chains in 1:1 atom ratio were galvanostatically deposited on a Cu substrate for catalyzing hydrogen evolution reaction (HER) in H2SO4 electrolytes. The morphology and composition of the deposits were characterized by FE-SEM/EDX analysis. All the four-level branches of the dendritic nanoalloy grow in a pearl chain structure of nanoparticles with a diameter of ca. 50-80 nm. The electrocatalytic activity to HER was studied by linear polarization and chronopotentiometry. At the NiCu nanoalloy electrode, the exchange current density of HER was 2836 times higher than at Cu electrode, while the overpotential at a current density of 50 mA cm-2 was decreased by 265 mV. The NiCu nanoalloy can not only significantly reduce the charge transfer resistance of HER, but also facilitate the elimination of the generated hydrogen from the active sites. This work indicates that the dendritic NiCu nanochains may be a potent candidate as a non-noble metal catalyst for hydrogen energy production. | |||
TO cite this article:LIU Lu,HE Jianbo. Dendritic NiCu nanopearl chains for electrocatalytic production of hydrogen in acidic media[OL].[15 February 2016] http://en.paper.edu.cn/en_releasepaper/content/4678239 |
4. Confined Space Synthesis of Mesoporous Silica Nanoparticles with a Three Dimensionally Ordered Close-packing Structure | |||
WANG Jing,CHEN Huiyong | |||
Chemistry 25 December 2015 | |||
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Abstract:Mesoporous silica nanoparticles with a three dimensionally ordered close-packing structure (3DOc-p MSNs) were confined synthesis through steam-assisted crystallization treatment. With perfect replication from the three dimensionally ordered mesoporous carbon template, the obtained 3DOc-p MSNs presented a unique assembly structure of colloidal crystal composed of uniform mesoporous silica spherical particles with a controllable particle size ranged from 10 to 160 nm and various mesopore morphologies of hollow, multicellar, disordered wormlike, and ordered structure with the increasing of the confined space. Moreover, sonication induced fragmentation of 10, 20, and 40 nm 3DOc-p MSNs resulted in a clear suspension of highly monodispersed mesoporous silica nanoparticles with the corresponding particle size and mesopore structure. | |||
TO cite this article:WANG Jing,CHEN Huiyong. Confined Space Synthesis of Mesoporous Silica Nanoparticles with a Three Dimensionally Ordered Close-packing Structure[J]. |
5. The Nature of Se-N Dynamic Covalent Bond: The Conversion Between Se-N Covalent and Non-Covalent Bond Interactions | |||
Xie Meng,Gao Jun | |||
Chemistry 08 December 2015 | |||
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Abstract:The structures and nature of Se-N dynamic covalent bond between three kinds of pyridine derivatives [R-C5H4N, pyridine (R=H), methylpyridine (R=CH3), 4-dimethylamino-pryidine (R=N(CH3)2)] and phenylselenyl bromine (PhSeBr) have been analyzed using density functional theory. The interactions between Se atom in PhSeBr and N atom in pyridine or pyridine derivative can be divided into three models: dissociation, nonbonding interaction and covalent bond interaction. Quantum chemical calculations on three series compounds show that these three kinds of model structures can transform to each other, and resulting in the generation of Se-N dynamic covalent bond. In the process of structure conversion, electron transfer is presence. Solvent effects especially in polar solvent such as CH2Cl2 can make the conversion between Se-N covalent bond and Se N nonbonding interactions easier. The substituent of the pyridine ring can affect the conversion: the stronger the electron-donating ability of the substituent is, the easier the structure transformation is. | |||
TO cite this article:Xie Meng,Gao Jun. The Nature of Se-N Dynamic Covalent Bond: The Conversion Between Se-N Covalent and Non-Covalent Bond Interactions[OL].[ 8 December 2015] http://en.paper.edu.cn/en_releasepaper/content/4668621 |
6. Exploring Halogen···Halogen Interactions in Molecular Packing: Benchmark and Theoretical Analysis | |||
LIU Fang,DU Likai,GAO Jun | |||
Chemistry 08 December 2015 | |||
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Abstract:The nonbonded halogen halogen (X…X) interactions play an important role in crystal engineering and material sciences. The X…X bond involving two or more halogen centers results in a very interesting donor-acceptor interaction due to their complicated anistropic character, in which each halogen atom could simultaneously be a donor and an acceptor. Their potential energy surface (PES) shows a dual well potential feature. Here, we present a systematic theoretical investigation of the nature of the X…X interactions. The stable geometries, as well as the PES of X…X dimers (FX, X=Cl, Br, I) were extensively studied with a series of theoretical methods. Interestingly, we find that the hybrid wavefunction based approaches (such as MP2.5) are indeed a good choice to obtain improved binding energies (<0.05 kcal/mol error) with reduced computational cost. Among the DFT methods, the statistical errors are significantly dependent on the selected functionals. We anticipate this study could provide us some insights on the future understanding of the feature of X…X interactions in molecular packing. | |||
TO cite this article:LIU Fang,DU Likai,GAO Jun. Exploring Halogen···Halogen Interactions in Molecular Packing: Benchmark and Theoretical Analysis[OL].[ 8 December 2015] http://en.paper.edu.cn/en_releasepaper/content/4668647 |
7. Catalytic Adsorptive Desulfurization Using TiO2/SBA-15 under Mild Conditions | |||
REN Xiaoling,XIAO Jing | |||
Chemistry 21 November 2015 | |||
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Abstract:This study investigates catalytic adsorptive desulfurization (CADS) of model diesel fuel using TiO2/SBA-15 under mild conditions. The TiO2/SBA-15 was prepared by a facile incipient wetness impregnation method and characterized by N2 adsorption and X-ray diffraction. The CADS referred to ADS performance were evaluated in a batch reactor. High desulfurization uptake of 12.7 mg/g was achieved at low sulfur concentration of 15 ppmw-S by TiO2/SBA-15 under CADS, which was two-magnitude higher than that under ADS without the in-situ catalytic oxidation of dibenzothiophene. Kinetic results suggested that the CADS equilibrium over TiO2/SBA-15 was reached fast in 0.5 h. In the CADS-TiO2/SBA-15 system, the TiO2 loading, cumene hydroperoxide/dibenzothiophene ratio and CADS temperature were optimized to be 10 wt.%, 2, and 35 C, respectively. Furthermore, desulfurization tests in 5 consecutive CADS-regeneration cycles suggested that the bi-functional TiO2/SBA-15 can be regenerated by acetonitrile washing followed with oxidative air treatment. The superior desulfurization uptake at low sulfur concentration range, fast adsorption kinetics, excellent regenerability, operation at mild conditions, and facile and low-cost adsorbent synthesis make the CADS-TiO2/SBA-15 system an effective and economic desulfurization approach for ultra-clean fuel production.. | |||
TO cite this article:REN Xiaoling,XIAO Jing. Catalytic Adsorptive Desulfurization Using TiO2/SBA-15 under Mild Conditions[OL].[21 November 2015] http://en.paper.edu.cn/en_releasepaper/content/4664409 |
8. Rapid Preparation of Graphene Hydrogel by Microwave Digestion Reduction and its application in supercapacitors | |||
Tang Yi,Wang Xingyan,Jin Xianming,Dai Youzhi,Wang Xianyou | |||
Chemistry 07 November 2015 | |||
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Abstract:Graphene hydrogels have been successfully prepared by a simple and fast microwave digestion through reducing graphene oxide, and used as the electrode materials for supercapacitors. The morphology, structure and components of the graphene hydrogel are characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS). The electrochemical performances of the graphene hydrogel are evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) in 6 M KOH electrolyte. The results show that the graphene hydrogels possess well-defined and interconnected 3D porous networks and exhibits excellent electrochemical performance for supercapacitors. Particularly, the MGH-10 prepared by microwave digestion within 10 mins shows the highest specific capacitance. The MGH-10 electrode owns specific capacitance as high as 204 F g-1 at the scan rate of 2 mv s-1, which is higher than Hydrothermal method. Furthermore, the MGH-10 supercapacitor delivers high energy densities of 6.8 W h kg-1 and 5.9 W h kg-1 at the power density of 1000 W kg-1 and 5000 W kg-1, respectively. | |||
TO cite this article:Tang Yi,Wang Xingyan,Jin Xianming, et al. Rapid Preparation of Graphene Hydrogel by Microwave Digestion Reduction and its application in supercapacitors[OL].[ 7 November 2015] http://en.paper.edu.cn/en_releasepaper/content/4660549 |
9. Formation of BaF2 micron particles as superhydrophobic materials via a hydrothermal method | |||
LAI Yuan,LI Feng,OU Gaoyu | |||
Chemistry 18 September 2015 | |||
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Abstract:Uniform superhydrophobic BaF2 micron materials with controllable morphology have been successfully synthesized via a facile hydrothermal process. The effects of reaction time, temperature, surfactants and pH are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and measuring the water contact angle (CA). The results show that an uniform BaF2 tetragonal phase structure was fabricated when the reaction temperature was controlled at 180 oC with a reaction time of 24 h. Besides, a static CA for water of 169 and a very low sliding angle (SA) were observed when the BaF2 materials were modified with fluorine silane methanol solution. | |||
TO cite this article:LAI Yuan,LI Feng,OU Gaoyu. Formation of BaF2 micron particles as superhydrophobic materials via a hydrothermal method[OL].[18 September 2015] http://en.paper.edu.cn/en_releasepaper/content/4654918 |
10. Preparation of Iodo-Bodipy dimer as triplet photosensitizers and Application in Photooxidation and Triplet-Triplet Annihilation (TTA) Upconversion | |||
CUI Xiaoneng,ZHAO Jianzhang | |||
Chemistry 04 August 2015 | |||
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Abstract:Iodo-boron dipyrromethene (Bis-bodipy) dimer (B-4I) was prepared as organic triplet photosensitizer for triplet-triplet annihilation (TTA) upconversion and photooxidation. We introduces four iodine atoms to the Bodipy chromophore, therefore the intersyster crossing (ISC) was improved compared to the single iodo-boron dipyrromethene. The organic photosensitizers show strong UV-vis absorptions at 490-590 nm. Long-lived triplet excited state (triplet lifetime up to 72.2 μs) is populated upon excitation of the photosensitizers, proved by nanosecond time-resolved transient absorption spectroscopy. The triplet state was located in the Bodipy part for B-4I by DFT caculations of spin density surface analysis. The singlet oxygen quantum yield is up to 90%, which is higher than traditional photosensitizers, such as tetraphenylporphyrin (TPP), Rose Bangel (RB) and Methylene Blue (MB). In the photooxidation reactions of 1,5-dihydroxy naphthalene, the product Juglone was obtained with high yield. The TTA upconversion was also studied with B-4I as the triplet photosensitizer and with perylene as triplet acceptor, the upconversion quantum yield is up to 5.76%. | |||
TO cite this article:CUI Xiaoneng,ZHAO Jianzhang. Preparation of Iodo-Bodipy dimer as triplet photosensitizers and Application in Photooxidation and Triplet-Triplet Annihilation (TTA) Upconversion[OL].[ 4 August 2015] http://en.paper.edu.cn/en_releasepaper/content/4651799 |
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