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71.
Two organic-polyoxometalates (organic-POMs) hybrids were constructed by fan-shaped 1-methyl-3-[3, 4, 5-tris(octadecyloxy) benzyl]imidazolium salts (labelled as I–Cl) and triethyl-[3, 4, 5-tris (octadecyloxy) benzyl] ammonium salts (labelled as Q–Cl) and Keggin anions [SiW12O40]4? by electrostatic interaction. Self-assembled behaviours of two aggregates in organic solvent and solid state were investigated in detail by scanning electron microscopy, transmission electron microscopy and X-ray analysis. The mixed solution of chloroform–methanol or chloroform–acetone provided the stable environment for aggregates and aggregates showed a uniform micron size. X-ray analysis results showed that flower-like aggregates morphology of I4[SiW12O40] based on imidazole ring as ‘head’ in organic cations was formed by the stacking of multilamellar discs and kept the lamellar structure in solid state. Bulk thorn spheres appeared in Q4[SiW12O40] aggregates, which were formed by closely interspersed of lots flatted blocks with hexagonal structure characteristics in solid state. The comprehension for the self-assembly morphology and solid structure of organic-polyoxometalate hybrids would help us to use easily modified organic moiety and functional inorganic polyoxoanions as blocks to build novel and giant supramolecular architecture. 相似文献
72.
Lei Wang Jinxiu Wang Songlin Zhang Wenchao Liao 《Plasma Chemistry and Plasma Processing》2017,37(6):1463-1474
In this study, efficient decomposition and debromination of monobromoacetic acid (MBAA) induced by radio frequency discharge in an aqueous solution in the concentration range from 0.1 to 8.0 mM were investigated. The decomposition and debromination intermediate byproducts were analyzed by ion chromatography. The experimental results showed that the decay of MBAA followed first-order kinetics. Increasing pH and adding organic additives to the solution enhanced MBAA removal and debromination. Acetic acid, bromate ion, oxalic acid and formic acid were determined as the major intermediate byproducts. Final products were bromide ion and carbon dioxide. Hydrated electrons are the primary species for the debromination and reactive oxygen species are the ones for the decomposition. A probable reaction pathway was proposed. The present study may provide a promising alternative for the complete mineralization of MBAA. 相似文献
73.
Yan-Shuang MENG Chen WANG Lei WANG Gong-Rui WANG Jun XIA Fu-Liang ZHU Yue ZHANG 《物理化学学报》2017,33(9):1915-1922
Sulfur and nitrogen co-doped porous carbon (SNDPC) was successfully synthesized using one-step microwave-assisted pyrolysis of ionic liquid. The structure and morphology of the pyrolysis products were characterized by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), electron microscopy, and X-ray photoelectron spectroscopy (XPS). The pyrolysis mechanism of the ionic liquid 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide (EMImNTf2) under microwave irradiation was discussed. Microwave irradiation was found to accelerate the pyrolysis of EMImNTf2. The cation of EMImNTf2 works as the precursor of the carbon backbone of the porous carbon, while the anion acts as sulfur source and porosity-directing regulator. The SNDPC was obtained at 320 ℃ and exhibited graphitic structure with numerous surface defects. The atomic percentages of N and S in SNDPC were 12.84% and 1.07%, respectively. The N atoms mainly substitute the C sites in the graphitic carbon matrix, whereas the S atoms mainly bond to the ledges and defects of the carbon matrix. 相似文献
74.
对不同断面形状的深埋隧洞进行了分析,比较了隧洞围岩应力解析解与通过当量半径方法得到的近似解之间的差别.首先,应用复变函数的基本理论,给出圆形、椭圆、矩形、直墙拱形等几种常见深埋隧洞围岩应力的解析表达式.其次,应用当量半径的折算形式,将其任意形状的边界转化为标准圆形断面,利用Lamé解答得到了各围岩应力分量.最后,考虑隧洞断面形状参数的变化,通过数值算例对精确解和近似解进行了比较,分析了当量半径折算形式的精确度.在此基础上,应用有限元方法验证了复变函数解析解的精确性,以椭圆、矩形和直墙拱形的复变函数解验证当量半径精确度.结果表明,当量半径的折算形式解答与精确解答之间相似程度与隧洞的断面形状和几何参数之间有着密切的关系. 相似文献
75.
Dynamic mechanical behaviour of natural rubber-silica composites was studied by a frequency sweep method at different temperatures (40 °C,70 °C and 100 °C) using a dynamic mechanical analyzer and a rotorless rheometer, RPA, in an attempt to establish a correlation between the two. The composites with silica content up to 40 phr were studied. It was found that the dependence of dynamic modulus on the frequency as obtained from both the instruments followed a similar trend. This suggests that the dynamic mechanical properties of rubber compounds can be determined even during curing. A correlation could be arrived at between the two sets of data, making it possible to predict one set knowing the other. The impact of silane coupling agent, bis (3-triethoxysilylpropyl tetrasulphide), TESPT, on viscoelasticity was also investigated. The mechanical properties were improved in the presence of TESPT. Additionally, an increase in thermal stability was also observed in the presence of TESPT. Scanning electron micrographs showed the better filler dispersion in the case of silane-coupled silica composites. 相似文献
76.
Shunxi Li Ruoyu Xu Hui Wang Dan J. L. Brett Shan Ji Bruno G. Pollet Rongfang Wang 《Journal of Solid State Electrochemistry》2017,21(10):2947-2954
A nitrogen (N)-doped mesoporous carbon material exhibiting ultra-high surface area was successfully synthesized from sheep bones via a facile and low-cost method. The obtained carbon material had an ultra-high specific surface area of 1961 m2 g?1 and provided rich active sites for the oxygen reduction reaction (ORR), which in turn resulted in high electrocatalytic activity. It was found that the pore size distribution for the newly prepared carbonaceous material fell in the range of 1–4 nm. Benefiting from its high surface area and the presence of pyridine-N and quaternary-N species, the as-prepared carbon material exhibited excellent ORR activity in an oxygen-saturated 0.1 M KOH solution, compared to commercial Pt/C (10 wt%). Due to its high ORR catalytic activity, stability and low-cost, using sheep bone as C and N precursors to produce N-doped carbon provides an encouraging step toward the goal of replacing commercial Pt/C as fuel cell cathode electrocatalyst. 相似文献
77.
Yan -Zheng Chen Ping Li Xia Zhao Jian-Qiang Zhang He-Ming Luo 《Journal of Solid State Electrochemistry》2017,21(1):171-181
Nitrogen-doped porous carbons were prepared using a facile method, with low-biotechnology fulvic acid potassium salts as a precursor. The prepared carbons had a high surface area (1623 m2 g?1) and good electrochemical properties, making them suitable electrode materials for supercapacitors. Nitrogen-doped porous carbons were tested as an electrode in both 6 M KOH aqueous solution and different concentrations KNO3 aqueous solution. The nitrogen-doped porous carbons with unique microstructure and nitrogen functionalities exhibited a capacitance of 235 F g?1 in a 6 M KOH aqueous solution. Electrochemical investigation showed that the nitrogen-doped porous carbons exhibited a broad potential operational window in a 2.5 M KNO3 aqueous solution. Furthermore, a high capacitance retention of 88.1 % was achieved even after 5000 cycles at 1.7 V. Potassium nitrate solutions in a wide range of concentrations were also proven to be promising electrolytes for electrochemical capacitors because they are cheap, noncorrosive, electrochemically stable, and compatible to diverse current collectors. 相似文献
78.
Yubo Shao Jing Du Hua Li Yongqing Zhao Cailing Xu 《Journal of Solid State Electrochemistry》2017,21(1):183-192
A series of Ni0.37Co0.63S2-reduced graphene oxide nanocomposites with different graphene contents (NCS@rGO-x) has been successfully prepared via a facile one-step hydrothermal method and applied as the catalysts for the oxygen evolution reaction (OER) and degradation of organic pollutants. The XRD and FESEM analyses revealed that the phase structure and morphology of NCS nanoparticles were substantially influenced by the graphene contents. The phase structure of NCS nanoparticles gradually transformed from primary NiCo2S4 to Ni0.37Co0.63S2 and the morphology and size of NCS nanoparticles were found to become more regular and homogeneous with the increase of graphene concentration. On the NCS@rGO-x nanocomposites, the NCS@rGO-2 sample demonstrated the best catalytic activity toward the OER, which delivers a stable current density of 10 mA cm?2 at a small overpotential of ~276 mV (vs. RHE) with a Tafel slope as low as 48 mV dec?1. Furthermore, the NCS@rGO-2 sample showed the remarkable photocatalytic activity for degradation of methylene blue (MB), which may be attributed to the increased reaction sites and high separation efficiency of photogenerated charge carries due to the electronic interaction between NCS nanoparticles and rGO. All these impressive performances indicate that the NCS@rGO-2 nanocomposite is a promising catalyst in energy and environmental fields. 相似文献
79.
80.
Peng Liu Hui Ruan Tiantian Li Jiaqi Chen Fuqiu Ma Duoqiang Pan Wangsuo Wu 《Molecules (Basel, Switzerland)》2021,26(4)
The low cost β-zeolite and ethylenediamine modified β-zeolite (EDA@β-zeolite) were prepared by self-assembly method and used for Cu(II) removal from contaminated aqueous solution. Removal ability of β-zeolite toward Cu(II) was greatly improved after ethylenediamine (EDA) modification, the removal performance was greatly affected by environmental conditions. XPS results illustrated that the amide group played important role in the removal process by forming complexes with Cu(II). The EDA@β-zeolite showed desirable recycling ability. The finding herein suggested that the proposed composite is a promising and suitable candidate for the removal of Cu(II) from contaminated natural wastewater and aquifer. 相似文献