乙炔黑涂层对锂硫电池性能的影响

锂硫电池的循环放电稳定性较低,因此我们采用一种低成本的方法改善锂硫电池的性能,即在硫电极表面制备乙炔黑涂层并测试了材料的形貌结构及电化学性能。结果表明,在硫含量（质量分数）70%的硫-乙炔黑复合材料中,硫附着在乙炔黑颗粒表面。接着在硫电极表面制备了厚度15 μm左右的乙炔黑涂层,乙炔黑涂层-硫电极的氧化反应电位低于硫电极,说明乙炔黑涂层有助于硫电极氧化反应的进行。与硫电极相比,乙炔黑涂层-硫电极活性物质的聚集程度低于硫电极,乙炔黑涂层-硫电极具有更高的放电比容量和循环放电稳定性。在150次循环充放电后,乙炔黑涂层-硫电极的放电比容量为894 mAh·g^-1。     

氢氧化铜纳米线-乙炔黑复合修饰碳糊电极用于壬基酚的电化学分析

采用配位均匀沉淀法制备氢氧化铜纳米线,并制备了氢氧化铜-乙炔黑复合修饰碳糊电极。该修饰电极与裸碳糊电极相比,具有高的灵敏度、良好的稳定性和重现性。在优化条件下,采用微分脉冲伏安法测得壬基酚氧化峰电流与浓度的线性范围为7.50×10-8~1.75×10-5 mol/L,检测限为1.26×10-8 mol/L。该方法应用于环境水样和土壤样品中壬基酚的检测,加标回收率为98.8%~105.6%。     

氯离子对硫化矿发电浸出过程影响的机理研究

采用双电池体系综合考虑了Cl-对硫化矿的FeCl3浸出过程的影响.研究结果表明,Cl-对所研究各硫化矿发电浸出的影响效果类似:阳极电解液中Cl-直接参与硫化矿发电浸出过程.发电输出功率随着Cl-浓度的增加而增加,但是浓度增大到一定程度时,其影响作用减弱.本研究对各矿物提出了相应的反应机理,建立了各体系发电浸出速率与[Cl-]的动力学关系,对镍精矿、铜精矿、闪锌矿及方铅矿体系分别为:模型与实验结果吻合.     

SDS存在下肌红蛋白在乙炔黑电极上的电化学行为研究

基于十二烷基磺酸钠(SDS)存在下,研究肌红蛋白(Mb)在乙炔黑电极上的电化学行为,建立了一种简便灵敏的肌红蛋白电化学分析方法.采用循环伏安法(CV)和差分脉冲伏安法(DPV)进行分析,SDS能显著提高肌红蛋白在乙炔黑电极上的还原峰电流.在最佳实验条件下,峰电流与肌红蛋白浓度在5.6×10-10 mol/L～2.8×10-7mol/L范围内有良好的线性关系,检出限为4.5×10-10 mol/L.方法用于合成样品中肌红蛋白含量的测定.乙炔黑电极可以作为传感器,用于样品中Mb的舍量测定.     

铁离子对硫化矿发电浸出过程影响的机理研究

本研究采用双电池体系考察了铁离子对硫化矿的FeCl3浸出过程的影响.研究结果表明,Fe3 对所研究各硫化矿发电浸出的影响效果类似:阴极电解液中Fe3*仅在较低的FeCl3浓度范围内(<0.1～0.2 mol L1)对发电浸出速率有显著影响.对各矿物提出了相应的反应机理,建立了各体系发电浸出速率与[Fe3 ]的动力学关系,对镍精矿、铜精矿、闪锌矿及方铅矿体系分别为:模型与实验结果吻合.     

碳材料电化学腐蚀的质谱-电化学循环伏安(MSCV)法研究 Ⅱ.催化剂的影响

用MSCV法研究了Pt催化剂作用下,碳材料在pH 0.3～11.8范围内的阳极腐蚀.Pt催化剂明显加速了活性炭及乙炔黑的腐蚀速度,使这两种电极上CO_2开始析出的电位φ_s明显负移,以致均负于φ_(O_2/H_2O).因此两种碳电极无论作为阳极还是氧阴极工作时均会被腐蚀.Pt对乙炔黑的催化活性明显强于活性炭.对于活性炭,Pt并不改变CO_2的φ_s-pH及η_s-pH曲线的形状(η_s-CO_2开始析出的超电势)(即无论有无Pt它们均为折点在pH～7的折线).然而乙炔黑的情况更为复杂.Pt使CO_2的φ_s-pH及η_s-pH形状从折线变为直线;在CO_2的I_(M-φ)曲线上出现两个波.它们似与乙炔黑上两种表面氧化物相对应.     

碳糊电极和化学修饰碳糊电极的制备及性能综述

碳糊电极在电化学研究中起着非常重要的作用．从电极材料选用和修饰剂选择方面综述了碳糊电极和化学修饰碳糊电极制备的几种方法,分析了碳糊电极和化学修饰碳糊电极制备技术存在的主要问题及其原因,评价了碳糊电极和化学修饰碳糊电极的表征技术、性能以及影响电极性能的因素．概括了近年来本课题组在碳糊电极研究中的一些结果．     

锂离子电池碳包覆锡负极性能研究

应用水热法分解葡萄糖制作锂离子电池碳包覆锡负极. 充放电测试表明,添加5%（by mass）乙炔黑导电剂的该电极初始放电比容量达967 mAh.g^-1,经50周循环其放电比容量仍保持362 mAh.g^-1,远高于锡电极的比容量（50周循环166 mAh.g^-1）. 碳包覆可防止锡粉团聚,降低锡的不可逆容量损失. 而添加乙炔黑可降低碳包覆电极与电解液间的交流阻抗,改善电极内部锂离子及电子的传导通道,从而也提高了该电极的初始放电比容量.     

一种基于乙炔黑/壳聚糖膜修饰电极的对氨基酚传感研究

制备了一种乙炔黑/壳聚糖薄膜修饰的玻碳电极,用循环伏安法详细研究了对氨基酚在该修饰电极上的电化学行为.结果表明: 对氨基酚在此膜修饰电极上呈现出一对可逆的氧化还原峰.相对于裸玻碳电极,该氧化还原峰的峰电流明显提高,峰电位差减小,可逆性变好,表明乙炔黑/壳聚糖薄膜电极对对氨基酚的电化学氧化具有良好的催化作用.对氨基酚的氧化峰电流与其浓度在1.0×10-7～2.0×10-6 mol/L和2 0×10-6～5.0×10-4 mol/L范围内均呈良好的线性关系; 检出限为5.0×10-8 mol/L(S/N=3).应用此修饰电极测定实际水样,结果较满意.     

碳材料电化学腐蚀的质谱-电化学循环伏安(MSCV)法研究 II:催化剂的影响

用MSCV法研究了Pt催化剂作用下, 碳材料在PH0.3～11.8范围内的阳极腐蚀.Pt催化剂明显加速了活性炭及乙炔黑的腐蚀速度, 使这两种电极上CO2开始析出的电位ΦO2/H2O。因此两种碳电极无论作为阳极还是氧阴极工作时均会被腐蚀。Pt对乙炔黑的催化活性明显强于活性炭, 对于活性炭, Pt并不改变CO2的ΦS-PH曲线的形状(ηS-CO2如析出的超电势)(即无论有无Pt它们均为折点在PH～7折线)。然而乙炔黑的情况更为复杂, Pt使CO2的ΦS-PH及ηS-PH形状从折线变为直线; 在CO2的IM-Φ曲线上出现两个波。它们似与乙炔黑上两种表面氧化物相对应。     

Carbon Black‐Modified Electrodes as Sensitive Tools for the Electrochemical Detection of Nitrite and Nitrate

Both screen‐printed electrodes modified with a dispersion of carbon black (CB) and solid paste electrodes prepared using a nanostructured CB were developed and characterized. Indeed, increasing the peak currents and/or their shifting to negative potentials were observed, exhibiting efficient electrocatalytic activity towards nitrite oxidation with high sensitivity and low detection limit. Solid carbon paste electrodes (SCPEs) and solid carbon black paste electrodes (SCBPEs) were challenged in amperometric mode with nitrite since detection limit reached is 65 and 5 nM respectively. Nitrate was first reduced to nitrite in reductor column, then detected on SCBPEs. Nitrate and nitrite were determined in real samples.     

Application of Different Carbon Materials for Carbon Paste Electrodes to Simultaneous Electrochemical Detection of four DNA Bases with High Simpleness

Three different carbon materials, graphite, graphene and multiwalled carbon nanotubes (MWCNTs), were applied to fabricate carbon paste electrodes and used directly as working electrodes without any further modification in a simple electrochemical system for simultaneous detection of four DNA bases, guanine, adenine, thymine and cytosine. EIS and SEM were used to characterize the formed carbon paste electrodes made from different carbon nanomaterials and silicon oil, respectively. Conditions for bases detection were studied, such as ratio of carbon nanomaterials to silicon oil, types of buffer saline and pH. An unexpected result was discovered that compared with graphite and graphene, MWCNTs in carbon paste electrodes were not able to obtain admirable electrochemical behavior, the possible reason of which was preliminary discussed. Individual and simultaneous detection of four bases were successfully carried out, with acceptable linear ranges and low detection limits. Furthermore, this facile method had admirable reproducibility, stability and acceptable recovery in real urine sample (97.62 % ∼103.36 %), indicating certain practical potential.     

Electrochemical Determination of Uric Acid,Dopamine and Tryptophan at Zinc Hexacyanoferrate Clay Modified Electrode

A Cameroonian smectite clay has been transformed into Zn²⁺ homoionic form and then used to prepare film modified glassy carbon electrodes and carbon paste electrodes. These electrodes containing Zn²⁺ were exploited to prepare a mixed valence zinc hexacyanoferrate (ZnHCF). Cyclic voltammetry has been employed to monitor the in situ growth of ZnHCF on clay modified electrodes. Although interesting electrocatalytic properties toward UA were observed with these modified electrodes, the modified carbon paste electrodes were the most suitable for dopamine, uric acid and tryptophan detection and exhibited for these analytes extended linear range, high sensitivities, selectivity and low limit.     

Voltammetric study of nifuroxazide at unmodified and Sephadex-modified carbon paste electrodes

The electrooxidation of nifuroxazide was investigated by cyclic and differential-pulse voltammetry at carbon paste and Sephadex-modified carbon paste electrodes. Nifuroxazide is irreversibly oxidized at all pH values and gives rise to a well-defined oxidation peak. The modification of the carbon paste surface with Sephadex allowed a preconcentration process to take place for nifuroxazide such that higher sensitivity was achieved compared with the bare surface. The influence of the scan rate, time of accumulation, modifier loading, solution conditions and pH on the adsorptive step at the modified carbon paste electrodes was investigated. The direct determination of the drug in urine is also discussed.     

Carbon paste electrodes: correlation between the electrochemical hydrogen storage capacity and the physicochemical properties of carbon blacks

The difficulties in the use of carbon paste electrodes to quantify the electrochemical adsorption of hydrogen in nanocarbon materials are described. Chronoamperometry studies using a Ferro/Ferri redox couple were performed to obtain the electrochemical active area of paste electrodes prepared by dispersion of differing samples of carbon blacks (CB) within silicon oil. This electrochemical active area was combined with the BET-surface area of the carbon blacks, to obtain the mass of superficial carbon involved in the electrochemical processes. To assure equal conditions for comparison, the electronic conductivity of the paste was equivalent in all the samples. From our results it appears that cyclic voltammetry, combined with carbon paste electrodes and nitrogen adsorption isotherms, provides a simple and less expensive route for the qualitative evaluation of the electrochemical hydrogen uptake of novel carbon materials. Still, for quantitative measurements, some issues remain unsolved in highly structured carbons, where the lack of penetration of the bulky Ferro/Ferri redox couple in the micropores of the CB and the occurrence of solid-state diffusion cause the underestimation of the mass involved in hydrogen adsorption.     

Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy

The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications.     

Voltammetric study of nifuroxazide at unmodified and Sephadex-modified carbon paste electrodes

The electrooxidation of nifuroxazide was investigated by cyclic and differential-pulse voltammetry at carbon paste and Sephadex-modified carbon paste electrodes. Nifuroxazide is irreversibly oxidized at all pH values and gives rise to a well-defined oxidation peak. The modification of the carbon paste surface with Sephadex allowed a preconcentration process to take place for nifuroxazide such that higher sensitivity was achieved compared with the bare surface. The influence of the scan rate, time of accumulation, modifier loading, solution conditions and pH on the adsorptive step at the modified carbon paste electrodes was investigated. The direct determination of the drug in urine is also discussed. Received: 2 June 1998 / Revised: 29 January 1999 / Accepted: 2 February 1999     

Effect of the modification of mercuric oxide on the properties of mercury films at HgO-modified carbon paste electrodes

The influence of modifications of the mercuric oxide on the voltammetric properties of mercury film carbon paste electrodes was studied. The mercury film was formed electrochemically from the bulk red or yellow mercuric oxide-modified carbon paste electrodes. Differential pulse anodic stripping voltammetry and optical microscopy in polarised light were used to characterise the properties of the mercury films. The results were compared with those obtained using the conventional preparation of mercury-plated carbon paste electrodes when the mercury film is deposited on the surface of the electrode by reduction of Hg(II) ions in solution utilising a sufficient negative potential. It was shown that the mercury film formed from the yellow modification of the mercuric oxide provides better voltammetric characteristics than the red one owing to the high distribution of its small particles, i.e. the mercury droplets after electrochemical treatment. Such a mercury film has similar properties to those of a mercury film generated from solution. Received: 06 December 1999 / Accepted: 16 March 2000     

Amperometric detection of phenolic compounds by polypyrrole-based composite carbon paste electrodes

This contribution describes new composite carbon paste electrodes (CPEs) for the determination of phenolic compounds. The composite CPEs were prepared by in situ generation of polypyrrole (PPy) within a paste containing the enzyme polyphenol oxidase (PPO). The best paste composition (enzyme/pyrrole monomer/carbon particles/Nujol) was determined for a model enzyme, glucose oxidase (GOx) according to the enzymatic activity of the resulting electrodes and to the enzyme leakage from the paste during storage in phosphate buffer. The in situ electrogenerated PPy improves the enzyme immobilisation within the paste since practically no enzyme was lost in solution after 72 h of immersion. Moreover, the enzyme activity remains particularly stable under storage since the biocomposite structure conserves 80% of its activity after 1 month of storage. Following the optimisation of the paste composition, PPO-based carbon paste biosensors were prepared and presented excellent analytical properties toward catechol detection with a sensitivity of 4.7 A M(-1) cm(-2) and a response time lower than 20 s. The resulting biosensors were applied to the determination of polyphenolic compounds (e.g., epicatechin and ferulic acid).