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31.
Molecular electroactive monolayers have been produced from vinylferrocene (VFC) via light-assisted surface anchoring to H-terminated n- and p-Si(1 0 0) wafers prepared via wet chemistry, in a controlled atmosphere. The resulting Si-C bound hybrids have been characterized by means of XPS and AFM. Their performance as semiconductor functionalized electrodes and their surface composition have been followed by combining electrochemical and XPS measurements on the same samples, before and after use in an electrochemical cell. White-light photoactivated anchoring at short (1 h) exposure times has resulted in a mild route, with a very limited impact on the initial quality of the silicon substrate. In fact, the functionalized Si surface results negligibly oxidized, and the C/Fe atomic ratio is close to the value expected for the pure molecular species. The VFC/Si hybrids can be described as (η5-C5H5)Fe2+(η5-C5H4)-CH2-CH2-Si species, on the basis of XPS results. Electrochemical methods have been applied in order to investigate the role played by a robust, covalent Si-C anchoring mode towards substrate-molecule electronic communication, a crucial issue for a perspective development of molecular electronics devices. The response found from cyclic voltammograms for p-Si(1 0 0) functionalized electrodes, run in the dark and under illumination, has shown that the electron transfer is not limited by the number of charge carriers, confirming the occurrence of electron transfer via the Si valence band. The hybrids have shown a noticeable electrochemical stability and reversibility under cyclic voltammetry (cv), and the trend in peak current intensity vs. the scan rate was linear. The molecule-Si bond is preserved even after thousands of voltammetric cycles, although the surface coverage, evaluated from cv and XPS, decreases in the same sequence. An increasingly larger surface concentration of Fe3+ at the expenses of Fe2+ redox centers has been found at increasing number of cv’s, experimentally associated with the growth of silicon oxide. Surface SiO− groups from deprotonated silanol termination, induced by the electrochemical treatments, are proposed as the associated counterions for the Fe3+ species. They could be responsible for the observed decrease in the electron transfer rate constant with electrode ageing. 相似文献
32.
冉隆文 《贵州科技工程职业学院学报》2007,2(2):24-26,38
主要阐述化工新工艺必须以人类的可持续发展为前提,强调资源的综合合理利用,注重环境保护等,并通过实例说明化工新工艺对可持续发展的贡献。 相似文献
33.
陈海珍 《宁波大学学报(理工版)》2004,17(4):444-448
选用了钛酸丁酯、硬脂酸和乙二醇作为表面活性剂,采用表面化学修饰和表面物理修饰2种方法修饰纳米氧化钛,然后分散在乙二醇溶剂中形成溶胶溶液.并通过红外光谱仪、紫外分光计、原子力显微镜,分析了表面化学修饰后的纳米氧化钛表面化学结构的变化,观测了纳米氧化钛溶胶在乙二醇溶剂中稳定性.试验结果表明表面活性剂与纳米氧化钛的表面的不饱和键之间形成了新的化学结构,粒子表面可能接枝上有机长链,提高了纳米粒子在溶剂中的相容性.表面化学修饰后的纳米氧化钛与乙二醇溶剂形成了较稳定的溶胶体系,而且纳米溶胶粒径较小.表面活性剂添加量与纳米粒子添加量控制在(1~1.2):1时,可以获得纳米溶胶粒径较小,同时溶胶稳定性较好的纳米氧化钛-乙二醇溶胶体系. 相似文献
34.
针对福建省煤田地质构造复杂,煤炭资源日益枯竭的现状.对构造复杂的煤层的特点及煤炭资源采出率低的原因进行分析,提出相应的提高煤炭资源采出率的有效措施. 相似文献
35.
V. I. Sakharov 《Fluid Dynamics》2007,42(6):1007-1016
The results of numerical simulation are presented for thermally and chemically nonequilibrium air plasma flows in a plasmatron discharge channel and underexpanded dissociated and partially ionized air jets flowing past a cylindrical model with a blunt leading edge and cooled copper surface under the experimental conditions realized in a VGU-4 100 kW induction plasmatron (Institute for Problems in Mechanics of the Russian Academy of Sciences) (see, for example, [1, 2]). The nonequilibrium excitation of the vibrational degrees of freedom of the molecules in the modal approximation and the difference between the electron and translational heavy-particle temperatures are taken into account in the calculations. The calculated data on the heat transfer and pressure at the stagnation point are compared with the results obtained within the framework of the thermally equilibrium model. Comparison with the experimental data obtained in the Institute for Problem in Mechanics of the Russian Academy of Sciences (Laboratory for interaction between plasma and radiation and materials) and kindly provided for comparison purposes gives satisfactory agreement. 相似文献
36.
《Fiber and Integrated Optics》2007,26(6):335-342
A fiber-optic chemical sensor (FOCS) for detection of nitrogen dioxide (NO2) molecules is reported. The FOCS presents an optropode structure because of the transmission properties of the sensitive material. The NO2 FOCS is activated by using the semiconductor polymer: regioregular head-to-tail poly(3-octylthiophene-2,5-diyl). The operation wavelength of the sensor is 543.5 nm such that a simple LED and detector can be used for the design of this device. The sensor response decreases after each exposure, demonstrating the reduction in sensitivity as well as irreversibility lower than 5%. However, its properties such as rapid response, high selectivity, high sensitivity (0.43 ± 0.01 muW/ppm), hygroscopic properties, and its operation at room temperature make this kind of FOCS a good alternative for NO2 toxic gas detection. 相似文献
37.
38.
目的探讨高等学校污水再生利用的可行性。方法以陕西某高校为例,采用类比分析法和效益分析方法。结果某高校除去部分较难处理污水,如冲厕所产生污水、厨房污水等,可用污水为2 528 m3/d,占总污水量的67%,经处理后得到可用水约2 000 m3/d,完全满足该校区1 658 m3/d杂用水量的预算。该校区如果实施污水再生利用,每年可以节省绿化、洗车等杂水费用约52.2万元,20年收益为1 044万元。其污水再生处理工艺适合采用生物接触氧化法。结论在高等学校实施污水再生利用是必要的,而且技术是可行的。 相似文献
39.
40.
The cocrystal of 1,2-bis(diphenylphosphinoyl)ethane (DPPEO) with phenol (1:1) were studied theoretically with AM1, PM3, MNDO and MINDO/3 semi-empirical methods to elucidate its structure. The bond lengths and angles from theoretical studies of molecule DPPEO/phenol (1:1) were found to be as expected. Theoretical results, concerning with intermolecular van der Waals forces in cocrystal, were compared with the previously obtained experimental data and AM1 results were found to be the best fit for bond lengths and angles of DPPEO/phenol. 相似文献