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1.
本文利用多种电化学方法研究了多晶电极上硫氰酸盐电化学氧化的动力学和机理,观察到电流和电位振荡。循环伏安测量表明氧化动力学分为二步过程。除了振荡现象,系统也展示双稳态,利用时间电位扰动,氧化反应可在高电位和低电位稳态之间转换,而且强烈吸附的惰性离子也可诱导从振荡转化为稳态。  相似文献   

2.
采用循环伏安法和恒电流电解法,以铂、镍、铜电极为工作电极,研究了苯甲醇在碱性溶液中的电氧化行为.用GC-MS和HPLC检测恒电流电解产物,在镍电极上苯甲醇可选择性地氧化为苯甲醛;在铂电极上主要产物为苯甲酸;在铜电极上则有苯甲酸和苯甲醛两种产物.通过循环伏安探讨了扫描速度、底物浓度及温度等因素对镍电极上电化学行为的影响.实验结果表明,在镍电极上苯甲醇的氧化反应为不可逆反应,受吸附步骤控制,其反应的活化能Ea为39.72kJ?mol-1.采用原位红外光谱法研究了碱性溶液中苯甲醇在镍电极上的反应机理,同时也进一步证实了其氧化产物为苯甲醛.  相似文献   

3.
以三唑酮(TDF)为目标污染物,以钛基钌铱电极和不锈钢板作阳极、阴极,颗粒活性炭(GAC)为粒子电极构建三维电极系统,通过搅拌实现粒子电极呈流化状态。研究电流密度、TDF初始浓度、GAC投加量、初始pH对三维电极系统的TDF去除效率的影响。研究结果表明:增大电流密度有助于提高TDF去除效率;TDF去除率随初始pH的增大呈现逐渐增大的趋势,碱性条件有助于TDF的去除;当GAC投加量为1~4 g/L时,增大GAC投加量有助于TDF的降解;增大TDF初始浓度会导致去除率的降低。当TDF初始浓度为200μg/L、电流密度为8m A/cm2、初始pH=11、GAC投加量为4 g/L时,电化学氧化10 min时TDF去除率达到99.95%。三维电极系统的传质效率高于二维电极系统,三维电极电化学氧化系统是一种适用于降解TDF的高级氧化技术。  相似文献   

4.
通过静电作用,在氧化石墨烯(GO)表面吸附一层均匀分散的Ni2+形成GO-Ni2+复合物,利用循环伏安法,把GO-Ni2+修饰电极上的Ni2+转化为铁氰化镍(Ni HCF),再通过电还原制备电还原的氧化石墨烯-铁氰化镍修饰的玻碳电极(ERGO-Ni HCF/GCE)。采用扫描电子显微镜(SEM)对其表面结构进行了表征。研究了NO-2在不同修饰电极上的电化学行为,ERGO-Ni HCF/GCE对NO-2的氧化反应有很好的电催化活性,NO-2的浓度与其氧化峰电流呈良好的线性关系。  相似文献   

5.
吕功煊  李振 《分子催化》2014,(4):351-358
在强碱性溶液中低电压低电流条件下在W基底上经阳极氧化得到致密WO3层,而后在酸性条件下在WO3表面经光辅助电化学还原沉积镍,所获得的复合电极具有优异的光电化学氧化水的活性和稳定性.SEM,EDX,XPS和TEM等表征表明复合电极中具有体心立方结构的W基底经阳极氧化形成了具有单斜结构的WO3层,表面修饰的镍物种以Ni(OH)2形式存在.光电化学实验表明WO3层对可见光具有良好的光响应,表面修饰镍后,光电氧化水的起始电位显著降低,电极的稳定性也得以提高.  相似文献   

6.
利用电化学循环伏安和极化曲线,考察了镍电极在不同浓度苯并咪唑(BMIH)-乙腈体系的缓蚀效果.结果表明,随着缓蚀剂BIMH浓度的增加,其氧化电位正移,且氧化电流降低,腐蚀电位正移.调制电位下测试镍电极表面BMIH吸附的现场表面增强拉曼光谱.随电位正移,BIMH可在镍电极表面吸附成膜,与金属镍生成配合物,阻止镍电极的腐蚀.并考察了不同浓度BIMH的成膜行为.结果发现,0.001 mol·L-1BIMH即可在镍电极表面成膜,这表明非水乙腈体系的镍表面,BMIH有较佳的缓蚀效果.  相似文献   

7.
无酶葡萄糖传感器   总被引:2,自引:0,他引:2  
利用葡萄糖在镍电极上的电化学氧化.制备了无酶葡萄糖传感器,研究了其电化学氧化机理.并测定了血清中葡萄糖的含量。在较高的pH值和570 mV的电位条件下,镍电极上产生的Ni(Ⅲ)具有氧化剂的作用,能直接氧化葡萄糖为葡萄糖酸内酯,产生的正比于葡萄糖浓度的电流响应可以定量样品中的葡萄糖含量。传感器由镍棒、铂丝对极和Ag/AgCl参比电极构成;对葡萄糖的响应时间小于1 min,进样间隔时间为3 min;对葡萄糖的电流响应范围为1.96×10~(-5)~1.80×10~(-4)mol/L,检测限为9.80×10~(-6)mol/L。传感器未使用葡萄糖氧化酶或其他生物酶,受温度的影响较小,样品中的氧对测定没有影响。在镍电极上,抗坏血酸、尿酸和多巴胺等物质不干扰血清中葡萄糖的测定。传感器用于测定血清中葡萄糖含量,相对标准偏差为4.3%。与己糖激酶法的测定结果一致。传感器制备简单,无需特殊保管,经简单处理后可重复使用。  相似文献   

8.
氧化还原蛋白质在模拟生物膜修饰电极上的直接电化学   总被引:8,自引:0,他引:8  
胡乃非  曾泳淮 《化学通报》2001,64(3):152-157
评述了氧化还原蛋白在模拟生物膜这种新型的化学修饰电极上的直接电化学研究的进展。对蛋白质在表面活性剂薄膜电极和多层复合薄膜电极上的电化学行为、模拟生物膜的超分子结构以及蛋白质在该类薄膜修饰电极上对不同底物的电催化性质进行了较详细的介绍。  相似文献   

9.
吡咯在乙二醇/乙睛混合溶剂中以对甲苯磺酸四乙基胺为支持电解质,在恒电流或恒电位条件下进行在镍电极上的电化学氧化聚合。元素分析及红外光谱表明有少量乙二醇参加了反应。扫描电镜图表明,在其接触镍电极的一面呈纤维状堆积,与在铂电极上的形态不同。电导率为10s/cm数量级。热失重分析表明,氧化态的聚吡咯膜在300℃以下是稳定的。  相似文献   

10.
Zn100-xTix合金电极的电化学性能   总被引:2,自引:1,他引:1  
锌镍电池;固相扩散法;Zn100-xTix合金电极的电化学性能  相似文献   

11.
Practical use of many bioelectronic and bioanalytical devices is limited by the need of expensive materials and time consuming fabrication. Here we demonstrate the use of nickel electrodes as a simple and cheap solid support material for bioelectronic applications. The naturally nanostructured electrodes showed a surprisingly high electromagnetic surface enhancement upon light illumination such that immobilization and electron transfer reactions of the model redox proteins cytochrome b5 (Cyt b5) and cytochrome c (Cyt c) could be followed via surface enhanced resonance Raman spectroscopy. It could be shown that the nickel surface, when used as received, promotes a very efficient binding of the proteins upon preservation of their native structure. The immobilized redox proteins could efficiently exchange electrons with the electrode and could even act as an electron relay between the electrode and solubilized myoglobin. Our results open up new possibility for nickel electrodes as an exceptional good support for bioelectronic devices and biosensors on the one hand and for surface enhanced spectroscopic investigations on the other hand.  相似文献   

12.
A hydrophilic carbon nanoparticle–sol-gel electrode with good electrical conductivity within the sol-gel matrix is prepared. Sulfonated carbon nanoparticles with high hydrophilicity and of 10–20 nm diameter (Emperor 2000) are co-deposited onto tin-doped indium oxide substrates employing a sol-gel technique. The resulting carbon nanoparticle-sol-gel composite electrodes are characterized as a function of composition and salt (KCl) additive. Scanning electron microscopy and voltammetry in the absence and in the presence of a solution redox system suggest that the composite electrode films can be made electrically conducting and highly porous to promote electron transport and transfer. The effect of the presence of hydrophilic carbon nanoparticles is explored for the following processes: (1) double layer charging, (2) diffusion and adsorption of the electrochemically reversible solution redox system 1,1′-ferrocenedimethanol, (3) electron transfer to the electrochemically irreversible redox system hydrogen peroxide, and (4) electron transfer to the redox liquid tert-butylferrocene deposited into the porous composite electrode film. The extended electrochemically active hydrophilic surface area is beneficial in particular for surface sensitive processes (1) and (3), and it provides an extended solid|organic liquid|aqueous solution boundary for reaction (4). The carbon nanoparticle–sol-gel composite electrodes are optimized to provide good electrical conductivity and to remain stable during electrochemical investigation.  相似文献   

13.
《Electroanalysis》2017,29(9):2125-2137
In this study, modified electrodes were constructed with the electropolymerization of metallophthalocyanines (MPcs) carrying redox active metal cations and electropolymerizable substituents. Then these electrodes were tested as selective and sensitive electrochemical pesticide sensors. Incorporation of the redox active Co(II) (CoPc(MOR‐NAF)), Cl–Mn(III) (MnPc(MOR‐NAF)), and Ti(IV)O (TiOPc(MOR‐NAF)) metal cations into Pc cavity increased the redox activity of Pc ring. Moreover, redox active and electropolymerizable 5‐{[(1E)‐(4‐morpholin‐4‐ylphenyl)methylene]amino}‐1‐naphthoxy substituents (MOR‐NAF) on the Pc ring triggered coating of the complexes on the electrode surface with the electropolymerization reactions. Therefore, modified electrodes GCE/MPc(MOR‐NAF) were constructed with the electropolymerizations of MPcs. These electrodes illustrated reasonable redox activity and conductivity for the potential applications in different fields of the electrochemical technologies. Pesticide sensing measurements indicated that changing the metal center of the complexes significantly altered their sensing activities. Among the complexes, GCE/CoPc(MOR‐NAF) electrode behaved as the most sensitive and selective electrode and it sensed the parathion with good selectivity and sensitivity. GCE/CoPc(MOR‐NAF) electrode showed a wider linear range (0.075‐5.75 μmoldm−3) and smaller LOD (0.025 μmoldm−3) and higher sensitivity (3.46 Acm−2M−1) for the parathion sensing. Although GCE/TiOPc(MOR‐NAF) electrode also sensed the parathion with a high sensitivity, its selectivity was poor and the linear range of this sensing was very narrow. Differently GCE/Cl–MnPc(MOR‐NAF) electrode only sensed eserine with reasonably sensitivity.  相似文献   

14.
Modified electrodes for NADH oxidation and dehydrogenase-based biosensors   总被引:1,自引:0,他引:1  
The direct electrochemical oxidation of beta-nicotinamide adenine dinucleotide (NADH) at clean electrodes proceeds through a radical cation intermediate at high overpotentials and is subject to rapid fouling. Consequently, there has been a considerable body of work over the last 20 years looking at ways in which to catalyse the reaction using a wide variety of different types of modified electrode. These studies have resulted in a good knowledge of the essential features required for efficient catalysis. In designing modified electrodes for NADH oxidation, it is not only important to identify suitable redox groups, which can catalyse NADH oxidation and can be attached to the electrode surface; it is also important to ensure facile charge transport between the immobilised redox sites in order to ensure that, in multilayer systems, the whole of the redox film contributes to the catalytic oxidation. One way to achieve this is by the use of electronically conducting polymers such as poly(aniline).  相似文献   

15.
Unique structured nanomaterials can facilitate the direct electron transfer between redox proteins and the electrodes. Here, in situ directed growth on an electrode of a ZnO/Cu nanocomposite was prepared by a simple corrosion approach, which enables robust mechanical adhesion and electrical contact between the nanostructured ZnO and the electrodes. This is great help to realize the direct electron transfer between the electrode surface and the redox protein. SEM images demonstrate that the morphology of the ZnO/Cu nanocomposite has a large specific surface area, which is favorable to immobilize the biomolecules and construct biosensors. Using glucose oxidase (GOx) as a model, this ZnO/Cu nanocomposite is employed for immobilization of GOx and the construction of the glucose biosensor. Direct electron transfer of GOx is achieved at ZnO/Cu nanocomposite with a high heterogeneous electron transfer rate constant of 0.67 ± 0.06 s(-1). Such ZnO/Cu nanocomposite provides a good matrix for direct electrochemistry of enzymes and mediator-free enzymatic biosensors.  相似文献   

16.
烟酸的电化学行为与测定   总被引:7,自引:0,他引:7  
用循环伏安法研究了不同支持电解质溶液中烟酸的电化学行为。烟酸在玻碳电极表面有良好的电化学响应信号。在碱性介质中,烟酸被不可逆氧化,氧化产物具有电活性,可发生准可逆氧化还原反应;在酸性介质中,烟酸发生两步准可逆氧化还原反应。结合红外、紫外光谱分析,提出了烟酸在不同酸度的介质中的电化学反应历程。并根据-0.13V处的氧化峰电流与烟酸浓度的关系,提出了电化学测定烟酸的新方法  相似文献   

17.
The electrochemical behavior of dopamine was examined under redox cycling conditions in the presence and absence of a high concentration of the interferent ascorbic acid at a coplanar, microelectrode array where the area of the generator electrodes was larger than that of the collector electrodes. Redox cycling converts a redox species between its oxidized and reduced forms by application of suitable potentials on a set of closely located generator and collector electrodes. It allows signal amplification and discrimination between species that undergo reversible and irreversible electron transfer. Microfabrication was used to produce 18 individually addressable, 4-μm-wide gold band electrodes, 2 mm long, contained in an array having an interelectrode spacing of 4 μm. Because the array electrodes are individually addressable, each can be selectively biased to produce an overall optimal electrochemical response. Four adjacent microbands were shorted together to serve as the collector, and were flanked on each side by seven microbands shorted as the generator (a ratio of 1:3.5 of electroactive area, respectively). This configuration achieved a detection limit of 0.454?±?0.026 μM dopamine at the collector in the presence of 100 μM ascorbic acid in artificial cerebrospinal fluid buffer, concentrations that are consistent with physiological levels. Enhancement by surface modification of the microelectrode array to achieve this detection limit was unnecessary. The results suggest that the redox cycling method may be suitable for in vivo quantification of transients and basal levels of dopamine in the brain without background subtraction.
Figure 1
Microelectrode array chip design and assignment of electrodes used for determination of dopamine (DA) in the presence of large excess of ascorbic acid (AA) by redox cycling. Analytes (DA and AA) are oxidized at the generator electrodes to form dopamine-o-quinone (DAQ) and dehydroascorbic acid (AAo) which diffuse to the nearest collector electrodes. DA is selectively detected at the collector electrodes, because DAQ can be reduced there, but AAo hydrolyzes to a nonelectroactive form prior to arrival  相似文献   

18.
Kwon SJ  Yang H  Jo K  Kwak J 《The Analyst》2008,133(11):1599-1604
Redox cycling of enzymatically amplified electroactive species has been widely employed for high signal amplification in electrochemical biosensors. However, gold (Au) electrodes are not generally suitable for redox cycling using a reducing (or oxidizing) agent because of the high background current caused by the redox reaction of the agent at highly electrocatalytic Au electrodes. Here we report a new redox cycling scheme, using nicotinamide adenine dinucleotide (NADH), which can be applied to Au electrodes. Importantly, p-aminophenol (AP) redox cycling by NADH is achieved in the absence of diaphorase enzyme. The Au electrodes are modified with a mixed self-assembled monolayer of mercaptododecanoic acid and mercaptoundecanol, and a partially ferrocenyl-tethered dendrimer layer. The self-assembled monolayer of long thiol molecules significantly decreases the background current of the modified Au electrodes, and the ferrocene modification facilitates easy oxidation of AP. The low amount of ferrocene on the Au electrodes minimizes ferrocene-mediated oxidation of NADH. In sandwich-type electrochemical immunosensors for mouse immunoglobulin G (IgG), an alkaline phosphatase label converts p-aminophenylphosphate (APP) into electroactive AP. The amplified AP is oxidized to p-quinoneimine (QI) by electrochemically generated ferrocenium ion. NADH reduces QI back to AP, which can be re-oxidized. This redox cycling enables a low detection limit for mouse IgG (1 pg mL(-1)) to be obtained.  相似文献   

19.
Redox reactions of oxygen have been considered critical in controlling the electrochemical properties of lithium‐excessive layered‐oxide electrodes. However, conventional electrode materials without overlithiation remain the most practical. Typically, cationic redox reactions are believed to dominate the electrochemical processes in conventional electrodes. Herein, we show unambiguous evidence of reversible anionic redox reactions in LiNi1/3Co1/3Mn1/3O2. The typical involvement of oxygen through hybridization with transition metals is discussed, as well as the intrinsic oxygen redox process at high potentials, which is 75 % reversible during initial cycling and 63 % retained after 10 cycles. Our results clarify the reaction mechanism at high potentials in conventional layered electrodes involving both cationic and anionic reactions and indicate the potential of utilizing reversible oxygen redox reactions in conventional layered oxides for high‐capacity lithium‐ion batteries.  相似文献   

20.
血红蛋白是脊椎动物红细胞内的呼吸蛋白,但由于其电活性中心不容易暴露以及在电极表面强烈吸附造成电极的钝化,使得它在一般固体电极上的电子传递速率很慢,得不到有效的电流响应。有关血红蛋白在固体电极上的电化学行为的研究很少。众多的分析化学家都在积极寻求加速血红蛋白电子传递速度的途径,使蛋白质直接电化学分析成为可能。最近的研究表明,某些染料修饰电极可以促进血红蛋白的电极过程,从而获得有效的电流响  相似文献   

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