二茂铁修饰碳糊电极对抗坏血酸的电催化作用的研究

研制了二茂铁修饰碳糊电极（简称ＦＭＣＥ）,探讨了该电极的性能和实用性。实验结果表明：该电极在ＮＨ３－ＮＨ４Ｃｌ缓冲溶液（ｐＨ＝９．３）中对抗坏血酸的氧化具有良好的电催化作用,峰电位Ｅｐａ＝＋０．２０Ｖ（ｖｓ．ＳＣＥ）,用恒电位电流法测得的氧化电流与抗坏血酸浓度在１×１０＾－６－１×１０＾－４ｍｏｌ·Ｌ＾－１,电极具有良好的重现性和选择性,响应时间短,使用寿命在６个月以上。用于检测果汁饮料中的抗坏血     

多壁碳纳米管一离子液体修饰电极同位镀铋膜测定铅离子

采用涂覆法制备多壁碳纳米管（MwCND-离子液体（[BMIM]PF6）修饰电极,然后在其表面同位镀铋膜,研究Pb“在该修饰电极上的阳极溶出伏安行为。实验结果表明,pb^2＋在修饰电极上于一0．5V产生灵敏的溶出峰,Pb^2＋在3．0×10。～2．0x10^-5mol／L浓度范围内与其溶出峰电流呈良好的线性关系,检出限为...     

基于COSMO-SAC模型对离子液体选择性的预测

以水,1,4二氧六环,丙酮,正己烷,1-辛醇,环己烷,苯以及离子液体的σprofile计算结果为基础,采用COSMO-SAC模型对各种两相系统的活度系数进行计算,以预测相平衡。预测了环己烷、苯、对二甲苯、间二甲苯和邻二甲苯在离子液体1-乙基-3-甲基咪唑四氟硼酸盐[Emim][BF_4]和1-丁基-3-甲基咪唑二氰胺盐[Bmim][(CN)_2N]中的无限稀释活度系数,为选择合适离子液体分离脂肪烃/芳香烃混合体系,对二甲苯/间二甲苯混合物,对二甲苯/邻二甲苯混合物提供依据。     

基于室温离子液体的肼蒸气传感器

利用电化学循环伏安法研究了水合肼蒸气在室温离子液体BmimPF6中的电化学行为,测得其在0.94V处可以被电化学氧化,且该氧化峰电流受肼在BmimPF6中的扩散所控制并推算出其氧化反应电子数为0.8.在此基础上,构建了以BmimPF6为电解质的准固态肼蒸气电化学气体传感器.该传感器对浓度范围为1.1～25.4μmol/L的水合肼蒸气呈线性响应.同时,该传感器也表现出了良好的稳定性与重复性.     

离子液体DSSC的性能测试

介绍了离子液体染料敏化太阳能电池（DSSC）的结构和工作原理,并对离子液体染料敏化太阳能电池进行了性能测试分析,探讨了不同入射光密度条件对短路电流、开路电压、填充因予、光电转换效率的影响,最后叙述了其他测试条件对离子液体DSSC光伏性能测试的影响。     

阻抗法监测离子液体膜的吸附性能

采用高频阻抗计测定了离子液体与有机溶剂相互作用过程中的电阻抗变化,选用1-甲基-3-正辛基咪唑氟硼酸盐([C8Mim]][BF4])作为模型离子液体,所用有机溶剂包括乙醇、丙酮、乙酸乙酯、四氯化碳.结果表明,在[C8Mim][BF4]中加入丙酮或乙醇后,混合物的电导率和介电常数显著增加,而加入四氯化碳所引起的阻抗变化较小.根据离子液体膜的阻抗变化可以监测膜的吸附特性,该文采用阻抗法和对电导率和介电常数有频率响应的串联式压电传感器实时检测了[C8Mim][BF4]膜吸附有机溶剂蒸气的过程,为研究离子液体的吸附性能提供了一种新的测量方法.     

体积连接性指数预测离子液体的室温粘度

离子液体(ILs)被视为潜在的"绿色溶剂",在溶剂的应用过程中粘度是最重要的热力学数据之一,但目前ILs的粘度数据仍然较为缺乏,除实验测定外,基团贡献、连接性指数等思想也为设计和筛选ILs提供了重要的性质预测方法。在已有的基于分子体积的粘度预测方法基础上,结合分子连接性指数来区分ILs不同基团的连接方式,建立了一个新的体积连接性指数模型用于预测ILs的室温粘度。由于该模型的基本参数来源于确定的基团物理体积值,因此为预测未知的ILs粘度等性质提供了可能性。通过对90种ILs室温粘度的预测,结果表明平均相对偏差为5.95%,方差检验所得的R~2和rmsd分别为0.9905和21cP,证明建立的模型可用于预测ILs的室温粘度。     

室温离子液体在气体和湿度传感器中的应用

室温离子液体由于其蒸气压低、离子导电性高、热稳定性好和电化学窗口宽等优良的物理化学特性而得到了广泛的重视,该文简略综述了近年来室温离子液体在气体和湿度传感器中应用的相关研究.     

离子液体作用下的噻吩加氢脱除机理研究

采用Materials Studio 6.1中的Dmol3程序,程序中的数字积分是medium水平,位移收敛标准、能量和受力分别是5×10^-3 A,2×10^-5 au/和4×10^-3 au/,利用DFT理论中的梯度校正GGAPW91方法和NDN机组计算。计算离子液体催化燃料油加氢脱硫过程的机理。通过对噻吩在离子液体酸性阴离子作用下的中间体和过渡态能量的研究,发现离子液体的阴离子不仅起到萃取作用,且在过渡态形成的过程中有促进加氢脱硫的作用,在一定的程度上起到催化剂的作用,并且活泼氢有利于噻吩加氢的进行。计算将为离子液体加氢脱硫机理提供重要的参考价值。     

纳米Ag_2O修饰碳糊电极的电化学性能研究

采用化学方法制备纳米Ag2O粒子,研究了5种不同组成的纳米Ag2O碳糊电极在不同底液中的电化学行为。实验了不同pH值底液种类以及碳糊组成对电极性能的影响。结果表明:纳米Ag2O含量为16%的碳糊电极电化学性能、可逆性能及吸附性能好,传输电荷的能力强,表现出了优越的电极性能。     

An inlaying ultra-thin carbon paste electrode modified with functional single-wall carbon nanotubes for simultaneous determination of three purine derivatives

A functional single-wall carbon nanotube film electrode (SWNTE) was constructed on the surface of inlaying ultra-thin carbon paste electrode (IUTCPE). The precursor film was formed by direct inlaying carbon paste onto nichrome substrate. Scanning electron microscope (SEM) was employed to characterize the electrode surface. The electrochemical behavior of SWNT/IUTCPE for xanthine (Xa), hypoxanthine (Hxa) and uric acid (UA) was investigated by various electrochemical techniques. The SWNT/IUTCPE exhibited an excellent electrocatalysis and enhancement of the current response for the purine derivatives. Three well-defined oxidation peaks of Xa, Hxa and UA were appeared at the electrode. The proposed electrode can be applied to determine Xa, Hxa and uric acid in human urine simultaneously without any pretreatment.     

A selective modified bentonite–porphyrin carbon paste electrode for determination of Mn(II) by using anodic stripping voltammetry

A novel voltammetric sensor based on chemically modified bentonite–porphyrin carbon paste electrode (MBPCE) has been introduced for the determination of trace amount of Mn(II) in wheat flour, wheat rice and vegetables. In this method Mn(II) gives well-defined voltammetric peak at the pH range of 3.5–7.5. For the preliminary screening purpose, the catalyst was prepared by modification of bentonite with porphyrin and characterized by thermogravimetric method (TG) and UV–vis spectroscopy. The detection limit (three times signal-to-noise) with 4 min accumulation is 1.07 × 10⁻⁷ mol L⁻¹ Mn(II). The peak currents increases linearly with Mn(II) concentration over the range of 6.0 × 10⁻⁷ to 5.0 × 10⁻⁴ mol L⁻¹ (r² = 0.9959). Statistical treatment of the results gave a relative standard deviation lower than 2.30%. The chemical and instrumental parameters have been optimized and the results showed that 1000-fold excess of the additive ions had not interferences on the determination of Mn(II).     

Application of carbon ionic liquid electrode for the electrooxidative determination of catechol

A carbon ionic liquid electrode (CILE) was constructed using graphite powder mixed with N-butylpyridinium hexafluorophosphate (BPPF₆) in place of paraffin as the binder, which showed strong electrocatalytic activity to the direct oxidation of catechol. In pH 3.0 phosphate buffer solution (PBS) a pair of redox peaks appeared on the CILE with the anodic and the cathodic peak potential located at 387 and 330 mV (vs. SCE), respectively. The electrochemical behaviors of catechol on the CILE were carefully investigated, and the electrochemical parameters were calculated with the results of the electrode reaction standard rate constant k_s as 1.27 s⁻¹, the charge-transfer coefficient α as 0.58 and the electron transferred number n as 2. Under the selected conditions, the anodic peak current increased linearly with the catechol concentration over the range from 1.0 × 10⁻⁶ to 8.0 × 10⁻⁴ mol L⁻¹ by cyclic voltammetry at the scan rate of 100 mV s⁻¹. The detection limit was calculated as 6.0 × 10⁻⁷ mol L⁻¹ (3σ). The CILE showed good ability to separate the electrochemical responses of catechol and ascorbic acid (AA) with the anodic peak potential separation as 252 mV (vs. SCE). The proposed method was further applied to the synthetic samples determination with satisfactory results.     

Differential pulse voltammetric determination of N-acetylcysteine by the electrocatalytic oxidation at the surface of carbon nanotube-paste electrode modified with cobalt salophen complexes

The preparation and electrochemical performance of the carbon nanotube-paste electrode modified with salophen complexes of cobalt(III) perchlorate, with various substituents on the salophen ligand, as well as their electrocatalytic activity toward the oxidation of N-acetylcysteine (NAC) is investigated. Several Schiff base complexes containing various nucleophilic and electrophilic functional groups were prepared, and their electrochemical characteristics for the electro-oxidation of NAC were evaluated using cyclic and differential pulse voltammetry (CV and DPV). The results revealed, the modified electrodes show an efficient and selective electrocatalytic activity toward the anodic oxidation of NAC among biologically important compounds in buffered solutions at pH of 7.0. The best voltammetric responses were obtained for a carbon-paste electrode (CPE) modified with a salophen complex containing para-methoxy groups on its salicylaldehyde ring. The analytical response of the modified electrode for response to other sulfhydryl compounds (e.g., cysteine, penicillamine, captopril and mercaptopropionyl glycine) in comparison to NAC was investigated by CV and DPV methods. The DPV method was applied as a sensitive method for the quantitative detection of the trace amounts of NAC. A linear dynamic range from 1 × 10⁻⁷ to 1 × 10⁻⁴ M with calibration sensitivity of 0.0646 μA/μM is resulted for NAC in DPV measurements. The detection limit was 5 × 10⁻⁸ M, which is remarkably lower than those reported previously for NAC using other modified electrodes. The results of voltammetric determinations show a very good reproducibility, and the R.S.D. for the slope of the calibration curve, based on 10 measurements in a period of two months, was <3.9%. The detection system provides very stable electrochemical responses toward NAC, makes it very suitable for using in pharmaceutical and clinical measurements.     

A novel microbial biosensor based on Circinella sp. modified carbon paste electrode and its voltammetric application

Microbial biosensors have been developed for voltammetric determination of various substances. This paper describes the development of a new biosorption based microbial biosensor for determination of Cu²⁺. The developed biosensor is based on carbon paste electrode consisting of whole cells of Circinella sp. Cu²⁺ was preconcentrated on the electrode surface at open circuit and then cathodically detected with the reduction of Cu²⁺. The voltammetric responses were evaluated with respect to percentage cell loading in the carbon paste, preconcentration time, pH of preconcentration solution, scan rate and interferences. The optimum response was realized by biosensor constructed using 5 mg of dry cell weight per 100 mg of carbon paste in pH 5.5 preconcentration solution. Under the optimum experimental conditions, the developed microbial biosensor exhibited an excellent current response to Cu²⁺ over a linear range from 5.0 × 10⁻⁷ to 1.0 × 10⁻⁵ M (r² = 0.9938) with a detection limit of 5.4 × 10⁻⁸ M (S/N = 3). The microbial biosensor had good sensitivity and reproducibility (R.S.D. 4.3%, n = 6). Finally, the applicability of the proposed microbial biosensor to voltammetric determination of Cu²⁺ in real sample was also demonstrated and validated with atomic absorption spectrophotometric (AAS) method.     

基于纳米金/碳纳米管修饰古墨电极测定大黄酸

本文首次采用自沉积方法将HAuCl4直接还原成纳米金颗粒并修饰在直接生长于石墨基体上的碳纳米管电极表面,制备了对大黄酸具有高催化性能的Au-CNTs／C电极。采用循环伏安法考察了大黄酸在Au—CNTs／C电极上的电化学行为,发现在-0．037V出现明显的氧化峰。在磷酸盐缓冲溶液P13S（DH=7．4）中,大黄酸的响应电流与浓度在1．8×10-4-2．5×10-3g／L范围内呈线性关系,相关系数为0．9878,其检测限为8．0×10^-4g／L。     

Preconcentration and voltammetric analysis of mercury(II) at a carbon paste electrode modified with natural smectite-type clays grafted with organic chelating groups

This study is devoted to the evaluation of a carbon paste electrode modified by a natural 2:1 phyllosilicate clay functionalized with either amine or thiol groups as a sensor for mercury(II). Functionalization was achieved by grafting the pristine clay via its reaction with 3-aminopropyltriethoxysilane (APTES) or 3-mercaptopropyltrimethoxysilane (MPTMS), respectively. The electroanalytical procedure comprises two steps: the chemical accumulation of the analyte under open-circuit conditions followed by the electrochemical detection of the preconcentrated species using differential pulse anodic stripping voltammetry. The different parameters that govern the two steps (accumulation time, concentration of the analyte, composition of the detection medium, potential and duration of electrolysis) were studied in detail. After optimization, a linear response was obtained in the concentration range from 0.1 to 0.7 μM Hg(II). In these conditions, the detection limits of the method were found to be 8.7 × 10⁻⁸ and 6.8 × 10⁻⁸ M, respectively, for the amine- and thiol-functionalized clays, on the basis of a signal-to-noise ratio of 3. The effect of potential interference on the determination of Hg(II) by the carbon paste electrode modified with the thiol-functionalized clay was also studied and the applicability of the method to real sample analysis was evaluated.     

Anodic stripping voltammetric determination of copper(II) using a functionalized carbon nanotubes paste electrode modified with crosslinked chitosan

The development and application of a functionalized carbon nanotubes paste electrode (CNPE) modified with crosslinked chitosan for determination of Cu(II) in industrial wastewater, natural water and human urine samples by linear scan anodic stripping voltammetry (LSASV) are described. Different electrodes were constructed using chitosan and chitosan crosslinked with glutaraldehyde (CTS-GA) and epichlorohydrin (CTS-ECH). The best voltammetric response for Cu(II) was obtained with a paste composition of 65% (m/m) of functionalized carbon nanotubes, 15% (m/m) of CTS-ECH, and 20% (m/m) of mineral oil using a solution of 0.05 mol L⁻¹ KNO₃ with pH adjusted to 2.25 with HNO₃, an accumulation potential of −0.3 V vs. Ag/AgCl (3.0 mol L⁻¹ KCl) for 300 s and a scan rate of 100 mV s⁻¹. Under these optimal experimental conditions, the voltammetric response was linearly dependent on the Cu(II) concentration in the range from 7.90 × 10⁻⁸ to 1.60 × 10⁻⁵ mol L⁻¹ with a detection limit of 1.00 × 10⁻⁸ mol L⁻¹. The samples analyses were evaluated using the proposed sensor and a good recovery of Cu(II) was obtained with results in the range from 98.0% to 104%. The analysis of industrial wastewater, natural water and human urine samples obtained using the proposed CNPE modified with CTS-ECH electrode and those obtained using a comparative method are in agreement at the 95% confidence level.