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蛋白质是生命的基础,研究氧化还原蛋白质的直接电化学不仅对模拟生物体系电子传递机理具有重要意义,而且为传感器的构筑提供了理论基础。遗憾的是,蛋白的直接电化学在裸电极上很难实现,许多研究者通过在电极上引入表面活性剂来克服该缺点.值得思考的是为什么在表面活性剂存在下,蛋白与电极之间才能实现直接电化学?甚至促进蛋白与电极之间的电子转移速率?因此研究表面活性剂在电极表面上的形态非常必要.我们主要讨论不同乙氧基单元的表面活性剂与蛋白之间在玻碳电极上的电子转移过程.结果表明不同表面活性剂提供给蛋白不同的微环境.当表面活性剂的乙氧基链长达到最佳值时,该修饰电极能固载更多的蛋白.我们利用紫外光谱法检测蛋白在固载过程中是否变性,同时也对所构筑的修饰电极的电催化性能进行表征. 相似文献
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脉冲激光沉积纳米TiO2薄膜电极的现场光电化学 总被引:1,自引:0,他引:1
在O3 /O2 气氛中采用 35 5nm激光烧蚀金属钛靶的反应性沉积薄膜方法 ,成功地在镀ITO膜的玻璃基片上制备了纳米锐钛矿相TiO2 薄膜电极 .用循环伏安法研究了在Li/TiO2 电池中TiO2 薄膜电极的电化学嵌入Li离子的行为 .由现场快速紫外可见吸收光谱实时监测TiO2 薄膜电极的显色特性 ,在波长 42 0和 6 5 0nm附近出现 2个明显的吸收峰 ,并发现TiO2 薄膜电极的吸收谱的涨落过程与Li离子的嵌入和脱嵌过程具有相关性与可逆性 ,表明该纳米TiO2 薄膜电极具有高质量的光电化学性能 . 相似文献
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通过层层自组装技术,以结晶的二氧化钛为原料,在不使用聚电解质的情况下,免除了高温煅烧,直接在柔性透明导电基底上制备了全纳米二氧化钛颗粒自组装薄膜。二氧化钛源主要包括带有异种电荷的锐钛矿二氧化钛溶胶和Degussa的P25二氧化钛,溶胶中的超细二氧化钛纳米晶在制备过程中起到了调节薄膜微观结构的作用,提高了薄膜的均匀性和致密度。将二氧化钛自组装薄膜作为工作电极,在三电极体系中进行光电化学测试,表面均匀致密的二氧化钛薄膜电极表现出了更高的光电化学性能,加入溶胶后获得的自组装薄膜电极所得到的光电流强度较由全P25组装的薄膜电极提高了近25%。 相似文献
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The polyelectrolyte-surfactant complex DHP-PDDA was prepared by reacting the anionic surfactant dihexadecylphosphate (DHP) with polycationic poly(diallyldimethylammonium) (PDDA). Thin films made from DHP-PDDA on solid substrates demonstrated an ordered multibilayer structure by XRD and DSC. Incorporated myoglobin (Mb) in DHP-PDDA films on pyrolytic graphite (PG) electrodes showed a pair of well-defined and nearly reversible cyclic voltammetric peaks for the Mb Fe(III)/Fe(II) couple at about -0.3 V vs SCE in pH 7.0 buffers. Electron transfer between Mb and PG electrodes was greatly facilitated in the film microenvironment. The positions of the Soret absorption band suggest that Mb maintains its secondary structure similar to its native state in DHP-PDDA films in the medium pH range. Mb could act as an enzyme-like catalyst in DHP-PDDA films as demonstrated by catalytic reduction of trichloroacetic acid, nitrite, and oxygen with a decrease in the electrode potentials required. Mb-DHP-PDDA films may thus have potential application as biosensors. Copyright 2001 Academic Press. 相似文献
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Heme proteins were immobilized on glass carbon electrodes by poly (N-isopropylac-yamide-co-3-methacryloxy-propyl-trimethoxysilane) (PNM) and exhibited a pair of well-defined, quasi-reversible cyclic voltammetric peaks at about -0.35 V versus a saturated calomel electrode in pH 7.0 buffer solution, corresponding to hemeFe(III)+e-->hemeFe(II). Some electrochemical parameters were calculated by performing nonlinear regression analysis of square wave voltammetry (SWV) experimental data. The formal potential was linearly dependent on pH, indicating the electron transfer of Fe(III)/Fe(II) redox couple accompanied by the transfer of proton. Ultraviolet visible and Fourier transform infrared spectra suggested that the conformation of proteins in the PNM films retained the essential feature of its native secondary structure. Atomic force microscopy images demonstrated the existence of interaction between heme proteins and PNM. N,N-dimethylformamide (DMF) played an important role in immobilizing proteins and enhancing electron transfer between proteins and electrodes. Electrochemical catalytic reductions of hydrogen peroxide and trichloroacetic acid by proteins entrapped in PNM film were also discussed, showing the potential applicability of the film modified electrodes as a biosensor. 相似文献
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The effect of various deposition techniques, electrode materials and posttreatment with tetrabutylammonium and tetrabutylphosphonium salts on the electrochemical behavior and stability of various Prussian blue (PB) modified electrodes, namely PB modified glassy carbon electrodes, silicate‐film supported PB modified glassy carbon electrodes, PB‐doped silicate glassy carbon electrodes, PB modified carbon ceramic electrodes using electrochemical deposition and PB modified carbon ceramic electrodes using chemical deposition is reported. Cyclic voltammetry and amperometric measurements of hydrogen peroxide were performed in a flow injection system while the carrier phosphate buffer (pH 7.0) with a flow rate of 0.8 mL min?1 was propelled into the electrochemical flow through cell housing the PB modified working electrode as well as an Ag|AgCl|0.1 M KCl reference and a Pt auxiliary electrode. The results showed that the deposition procedure, electrode material and posttreatment with additional chemicals can significantly alter the stability and electrochemical behavior of the PB film. Among the studied PB modified electrodes, those based on carbon ceramic electrodes modified with a film of electropolymerized PB showed the best electrochemical stability. 相似文献
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用电活性分子——硬脂酸二茂铁酯L-B膜修饰了薄膜CdSe电极,在单色光650nm光照下用循环伏安法研究修饰的薄膜电极的光电化学性能。研究结果指出经多层L-B膜修饰后,薄膜CdSe电极的,I-V性能和光稳定性都有明显改善。用界面能级关系讨论了硬脂酸二茂铁酯L-B膜在光照的CdSe薄膜/Fe(CN)64-溶液界面起传递电荷的中介作用,加速了界面的电荷转移。 相似文献
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Mercury film electrodes have been prepared on silver metal and silver-coated glassy-carbon supports and have been modified by a film of tri-n-octylphosphine oxide (TOPO) in a poly(vinyl chloride) matrix. The electrodes have been characterized in detail and the effects of the modifying film parameters on their electrochemical properties have been studied. It has been shown that these electrodes permit selective and sensitive determinations of many metals. The most important parameters are the thickness of the modifying film, the modifier-to-matrix ratio in the modifying film and the base electrolyte composition. Data concerning the reactions of a number of metal ions on the modified electrode are given. 相似文献
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Mercury-thin film electrodes coated with a thin film of poly(ester sulphonic acid) (PESA) have been investigated for application in the analysis of trace heavy metals by square wave anodic stripping voltammetry using the batch injection analysis (BIA) technique. Different polymer dispersion concentrations in water/acetone mixed solvent are investigated and are characterised by electrochemical impedance measurements on glassy carbon and on mercury film electrodes. The influence of electrolyte anion, acetate or nitrate, on polymer film properties is demonstrated, acetate buffer being shown to be preferable for stripping voltammetry applications. Although stripping currents are between 30 and 70% less at the coated than at bare mercury thin film electrodes, the influence of model surfactants on stripping response is shown to be very small. The effect of the composition of the modifier film dispersion on calibration plots is shown; however, detection limits of around 5 nM are found for all modified electrodes tested. This coated electrode is an alternative to Nafion-coated mercury thin film electrodes for the analysis of trace metals in complex matrices, particularly useful when there is a high concentration of non-ionic detergents. 相似文献
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T. L. Kulova N. F. Nikol’skaya A. M. Skundin 《Russian Journal of Electrochemistry》2008,44(5):558-563
Comparative studies of three type of carbonaceous materials—the modified oxidized graphite, thermoexpanded graphite, and carbon paper—prior to and after galvanostatic cycling in 1 M LiClO4 solution in propylene carbonate-dimethoxyethane mixture are carried out using standard porosimetry. It was shown that the mean (effective) thickness of the passive film [solid electrolyte interface (SEI)] at the electrodes of the modified oxidized graphite and thermoexpanded graphite equals a few nanometers. The comparison of porosimetric and electrochemical data shows that the passive film comprises both lithium carbonate and alkylcarbonates. Additionally, this comparison allows corroborating the concept on the formation of polymer (or oligomer) component of the passive film at least at the thermoexpanded graphite electrodes. 相似文献
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化学修饰电极的研究: 1:12磷钼杂多阴离子薄膜修饰电极的电化学性质 总被引:5,自引:0,他引:5
用循环伏安法研究了1:12磷钼杂多阴离子(PMo12)薄膜修饰电极的制备及其电化学行为, 发现PMo12膜强烈地吸附在玻璃碳电极表面, 溶液氢离子在PMo12膜改性电极的电化学过程中起着重要的作用, 而其它阴离子不参与这一过程, 在循环伏安法扫描过程中PMo12膜改性电极的稳定性很好。 相似文献
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Copper complex dye (C.I. Direct Blue 200) film modified electrodes have been prepared by multiple scan cyclic voltammetry. The effect of solution pH and nature of electrode material on film formation was investigated. The optimum pH for copper complex film formation on glassy carbon was found to be 1.5. The mechanism of film formation on ITO seems to be similar to that on GC surface but completely different mechanism followed with gold electrode. Cyclic voltammetric features of our modified electrodes are in consistent with a surface‐confined redox process. The voltammetric response of modified electrode was found to be depending on pH of the contacting solution. UV‐visible spectra show that the nature of copper complex dye is identical in both solution phase and after forming film on electrode. The electrocatalytic behavior of copper complex dye film modified electrode towards oxidation of dopamine, ascorbic acid and reduction of SO52? was investigated. The oxidation of dopamine and ascorbic acid occurred at less positive potential on film electrode compared to bare glassy carbon electrode. Feasibility of utilizing our modified electrode in analytical estimation of dopamine, ascorbic acid was also demonstrated. 相似文献
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A mathematical model of electrocatalytic processes taking place at conducting polymer modified electrodes has been developed.
The model takes into account the diffusion of solution species into a polymer film, diffusion of charge carriers within the
film, and a chemical redox reaction within the film. The space- and time-resolved profiles for reactant and charge carrier
concentration within the film, as well as dependencies of electric current on the concentration of solute species, reaction
rate constant and thickness of a polymer layer have been obtained and discussed. It has been shown that, even at a relatively
fast diffusion of charge carriers within the conducting polymer film, exceeding the diffusion rate of reactant by two orders
of magnitude, electrocatalysis of solute species at conducting polymer modified electrodes proceeds within the polymer film
rather than at the outer polymer/solution interface, i.e., electrocatalytic conversion follows a redox-mechanism rather than
metal-like one. Based on the results obtained, optimization of reaction system parameters could be made for any particular
case to get an optimum efficiency or reactant to product conversion.
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