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961.
采用基于色散校正的密度泛函理论进行了第一性原理研究, 详细分析了肼(N2H4)在Ni8Fe8/Ni(111)合金表面稳定吸附构型的吸附稳定性和电子结构及成键性质. 通过比较发现, 肼分子以桥接方式吸附在表面的两个Fe原子上是最稳定的吸附构型, 其吸附能为-1.578 eV/N2H4. 同时发现, 肼分子在这一表面上吸附稳定性的趋势为: 桥位比顶位吸附更有利, 且在Fe原子上比在Ni原子上的吸附作用更强. 进一步分析了不同吸附位点上稳定吸附构型的电子结构、电荷密度转移以及电子局域化情况. 结果发现: 相同吸附位点的电子态密度图基本一致, 并且N原子的p轨道和与之相互作用的表面原子的d轨道之间存在态密度上的重叠; 吸附后电荷密度则主要从肼分子转移到表面原子之上; 在电子局域化函数切面图中也发现吸附后电子被局域到肼分子的N原子和相邻的表面原子之间. 这些电子结构的表征都充分说明肼分子与表面原子之间通过电荷转移形成了强烈的配位共价作用. 相似文献
962.
铜氧化物高温超导体的发现, 打破了基于电声子相互作用BCS理论所预言的超导转变温度极限, 掀开了高温超导材料探索和高温超导机理研究的序幕. 根据掺杂类型的不同, 铜氧化物超导材料可以分为空穴型掺杂和电子型掺杂两类. 受限于样品, 对电子型掺杂铜氧化物的研究工作远少于空穴型掺杂体系. 本文简要回顾有关电子型掺杂铜氧化物超导体近期研究成果, 通过对比电子型掺杂和空穴型掺杂铜氧化物的相图来阐明电子型掺杂铜氧化物的研究对探索高温超导机理的必要性, 并特别针对电子型掺杂样品制备中的关键因素“退火过程”展开讨论. 结合课题组最新实验结果和相关实验报道我们发现电子型掺杂铜氧化物超导体在制备过程中除受到温度和氧分压的影响外, 退火效果还受到界面应力的强烈调制. 在综合考虑样品生长过程中温度、气氛及应力等多种因素的基础上, 探讨了“保护退火”方法导致电子型体系化学掺杂相图变化的起因. 相似文献
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Piao He Jian‐Guo Zhang Li‐Na Feng Kun Wang Tong‐Lai Zhang Shao‐Wen Zhang 《Journal of Physical Organic Chemistry》2015,28(6):423-427
1,5‐Daminotetrazole (DAT) is of much interest because of the practical significance and the diversity of characteristics. The study on the decomposition pathway and the kinetics of DAT has been performed based on the quantum chemistry theory. The minimum energy path (MEP) calculation has shown that NH2N3 and NH2CN are the initially detected products of DAT. And the structures of reactant, products and transition state were optimized with MP2 methods using 6‐311G** basis sets, and the energies were refined using CCSD(T)/6‐311G** levels of theory. The calculated rate constants were obtained using the conventional transition‐state theory (TST) and the canonical variational transition‐state theory (CVT) methods. The calculation results indicated that the energy barrier of decomposition reaction is 47.98 kcal mol?1 and the variational effect is small. In addition, the rate constants and the Arrhenius experience formula of DAT decomposition have been obtained between 200 and 2500 K temperature regions. The fitted three‐parameter expressions calculated using the TST and CVT methods are (TST) and (CVT). This work may provide the theoretical support for further experimental synthesis and testing. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
968.
A Novel L‐Cysteine Electrochemical Sensor Using Sulfonated Graphene‐poly(3,4‐Ethylenedioxythiophene) Composite Film Decorated with Gold Nanoparticles
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Xiaoqiang Wang Yangping Wen Limin Lu Jingkun Xu Long Zhang Yuanyuan Yao Haohua He 《Electroanalysis》2014,26(3):648-655
By exploiting the electrostatic interaction between positively charged 3,4‐ethylenedioxythiophene cation radicals and negatively charged sulfonated graphene (SG) sheets, we prepared a poly(3,4‐ethylenedioxythiophene)‐sulfonated graphene (SG‐PEDOT) composite film by a one‐step electrochemical process. The composite was further decorated with gold nanoparticles (AuNPs) and employed as an electrode material for the detection of L ‐cysteine (Cys). The SG‐PEDOT composite film is shown to provide a rough surface for the electrodeposition of AuNPs and to improve substrate accessibility and interaction with Cys. Moreover, the AuNPs‐decorated composite exhibits better electrocatalytic performance than that of a SG‐PEDOT composite only. Under optimum experimental conditions, the amperometric current of the sensor is linearly related to the concentration of Cys in the 0.1 to 382 µM range, and the detection limit is 0.02 µM (at S/N=3). The modified electrode displays favorable selectivity, good stability and high reproducibility. The method was successfully applied to the detection of Cys in spiked human urine. 相似文献
969.
Bin Cai Jun-Wei Zhao Bai-Feng Yang Huan He Guo-Yu Yang 《Journal of Cluster Science》2014,25(4):1047-1059
Hydrothermal reactions of trilacunary precursor A-α-AsW9O34 9? polyoxoanions and nickel ions in the presence of ethylenediamine (en = ethylenediamine) led to two new hexa-Ni-substituted Keggin-type tungstoarsenates [Ni6(μ 3-OH)3(en)3(H2O)6(B-α-AsW9O34)]·6H2O (1) and [Ni6(μ 3-OH)3(en)3(H2O)6(B-α-AsW9O34)]·10H2O (2), which have been characterized by elemental analyses, IR spectra, powder X-ray diffraction, thermogravimetric analyses and single-crystal X-ray diffraction. Crystal data for 1: hexagonal, R3c, a = b = 20.4379(5) Å, c = 21.5062(6) Å, β = 120º, V = 7779.8 (3) Å3 and Z = 6; for 2: momoclinic, P21/c, a = 13.4200(3) Å, b = 19.1428(5) Å, c = 22.8845(9) Å, β = 112.403(3)º, V = 5435.2(3) Å3 and Z = 4. Structural analyses reveal that the [Ni6(μ 3-OH)3(B-α-AsW9O34)] clusters in 1 and 2 are covalently functionalized by neutral en ligands, in which two similar {Ni6(μ 3-OH)3(en)3(H2O)6}9+ cores have been observed by our lab. Notably, 1 and 2 represent the highest number of substituted transition metal ions in all known lacunary Keggin-type polyoxotungstoarsenate monomers. 相似文献
970.
Qin Meng Guo-Ming Wang Huan He Bai-Feng Yang Guo-Yu Yang 《Journal of Cluster Science》2014,25(5):1295-1305
Two new pentaborates [M(dap)3][B5O6(OH)4]2·H2O (M = Co (1) and Ni (2); dap = 1,2-diaminopropane) have been hydrothermally synthesized. Both structures were determined by single crystal X-ray diffraction and further characterized by elemental analysis, FT-IR, thermogravimetric analysis and photoluminescence spectroscopy. Two compounds are isostructural and consist of isolated pentaborate [B5O6(OH)4]? anions and [M(dap)3]2+ complex cations. The anionic [B5O6(OH)4]? groups are linked by extensive hydrogen bonds to form a 3-D supramolecular framework with large channels, in which the transition-metal complex templates are located. The luminescent properties of 1 and 2 were studied, and blue luminescence occurs with an emission maximum at 405 and 408 nm upon excitation at 332 and 328 nm respectively. Crystal data: 1, monoclinic, space group P21/c (No. 14), a = 9.7159(5) Å, b = 29.3372(19) Å, c = 11.5121(6) Å, β = 103.286(5)°, V = 3193.6(3) Å3, Z = 4; 2, monoclinic, space group P21/c, a = 9.7264(4) Å, b = 29.3810(16) Å, c = 11.5185(6) Å, β = 103.249(4)°, V = 3204.0(3) Å3, Z = 4. 相似文献