质子惰性介质中硝基苯在铂微盘电极上的电化学行为

采用循环伏安法, 以铂微盘电极为工作电极, 铂片为辅助电极, 饱和甘汞电极为参比电极, 研究了硝基苯在含有四丁基高氯酸铵(TBAP)电解质的N,N-二甲基甲酰胺(DMF)有机溶液中的电化学行为, 并探讨了扫描速度和底物浓度等因素对硝基苯电化学特性的影响. 结果表明,该反应属扩散控制的准可逆反应.     

Monolithic integration of three-material microelectrodes for electrochemical detection on PMMA substrates

Monolithic integration of three-material microelectrodes for electrochemical detection on poly (methyl methacrylate) (PMMA) substrates is presented. Au–Ag–Pt three-material electrodes were all fabricated based on polymer compatible photolithography processes, and the fabrication sequence of the electrodes was optimized. The C–Ag–Pt three-electrode system was also demonstrated. To reduce the electrical resistance, the carbon electrode was made on a silver intermediate layer which was simultaneously fabricated with Ag electrodes. A PMMA/poly(dimethylsiloxane) electrochemical sensing microchip with the Au–Ag–Pt three-electrode systems was constructed. The reproducibility of the three-electrode system from single and different microchips was characterized. The performance of the microchip was evaluated by two kinds of electrochemical probes (Ru(bpy)₃Cl₂ and dopamine).     

Nanoporous platinum solid-state reference electrode with layer-by-layer polyelectrolyte junction for pH sensing chip

A novel solid-state reference electrode was developed by combining nanoporous Pt with polyelectrolyte junction. The polyelectrolyte junction was formed in the microchannel connecting the nanoporous Pt and the sample solution, and had layer-by-layer structure of oppositely charged polyelectrolytes. The layer-by-layer polyelectrolyte junction effectively blocked the mass transport of ions and maintains constant pH environments on the surface of the nanoporous Pt. The assembly of the polyelectrolyte junction and the nanoporous Pt, which produced reportedly a stable open-circuit potential in response to constant pH, exhibited outstanding performance as a solid-state reference electrode (e.g., excellent reproducibility of ±4 mV (n = 5), good long term stability of ±1 mV (for 50 h), and independence of solution environments like pH and ionic strength). A working principle of the solid-state reference electrode with layer-by-layer polyelectrolyte junction was suggested in terms of the roles of each layer and the effect of the neighboring layer. As a demonstrative application of the solid-state reference electrode, a miniaturized chip-type solid-state pH sensor comprised of two nanoporous Pt electrodes and a micro-patterned layer-by-layer polyelectrolyte junction was developed. The solid-state pH sensing chip showed reliable pH responses without liquid junction and successfully worked in a variety of buffers, beverages, and biological samples, showing its potential utility for practical applications. In addition, the solid-state pH sensing chip was integrated in a microfluidic system to be utilized for pH monitoring in microfluidic flow.     

光电催化降解邻苯二甲酸二乙酯的研究

采用sol-gel法制备TiO2薄膜光电极，以该电极为工作电极，铂丝作对电极，饱和甘汞电极为参比电极，对邻苯二甲酸乙酯的光电催化降解进行了研究。结果表明：该电极具有n型半导体的特征行为，在外加偏压为＋0．7v、pH=2、50mg／L的H2O2中对初始浓度为50mg／L的DEP溶液光照180min降解率达67．85％，讨论了氧的存在、外加偏压等因素对光电催化反应的影响。     

Square-wave voltammetric (SWV) determination of Captopril in reconstituted serum and pharmaceutical formulations

A simple, fast and sensitive square-wave voltammetric (SWV) method for the determination of trace amounts of Captopril in pharmaceutical formulation and reconstituted serum is reported. A three-electrode system containing the static mercury drop electrode (SMDE) working electrode, Pt auxiliary electrode and Ag/AgCl reference electrode was used throughout. Sodium sulfite was used as both supporting electrolyte and oxygen removing agent. No nitrogen purging is needed for oxygen removal from sample solution. Calibration graph showed good linearity in the concentration range of 0.5-50.0 μg mL⁻¹ of Captopril and regression coefficient of 0.9957 is obtained. R.S.D. for eight replicate measurements and LOD of the proposed method are 1.2% and 6.28 × 10⁻³ μg mL⁻¹, respectively. The effect of various parameters (equilibration time, scan increment, pulse height, drop size, frequency and sodium sulfite concentration) on the determination were investigated. The procedure was successfully applied to the determination of Captopril in pharmaceutical formulation and reconstituted serum.     

多孔电极电池的循环伏安法模拟

锂离子电池的全电池建模模拟对现代新能源领域的发展至关重要。伪二维（P2D）电化学模型是最常使用的全电池模拟模型,但一直被用于输入为电流,输出为电压的模拟中。本文基于P2D模型,通过对内电位、电极电位以及电池端电压的详细讨论,首次采用电压边界条件,利用COMSOL仿真软件完成了实验中常用的两电极体系和三电极体系的循环伏安法建模和模拟。并对比分析了两/三电极体系中扫描速率、颗粒半径、电极锂扩散速率以及最大嵌锂浓度这四个参数对循环伏安曲线形状的影响。结果表明,循环伏安测试时扫描速率越大,循环伏安曲线的峰值电流越大;固相锂扩散速率越大、电活性颗粒半径越小、最大嵌锂浓度越大,峰值电流越大。在相同的测试条件下,三电极体系比两电极体系的循环伏安图对称性更好,电流响应更大,并且颗粒半径、锂扩散速率及最大嵌锂浓度这三个参数对峰值电流的影响也更为明显。     

Microfabricated disposable lab-on-a-chip sensors with integrated bismuth microelectrode arrays for voltammetric determination of trace metals

This work reports the fabrication of disposable three-electrode cells with integrated metal-film electrodes. The devices were fabricated by a multi-step micro-fabrication approach combining sputtering for the deposition of metals and the dielectric material (SiO₂) on the surface of a silicon wafer and photolithography for the definition of the geometry of the sensors. The working electrode was a microelectrode array consisting of bismuth microdisks while the reference and counter electrode strips were made of Ag and Pt, respectively. The utility of these devices was tested for the trace determination of Pb(II) and Cd(II) by anodic stripping voltammetry and Ni(II) by adsorptive stripping voltammetry. The detection of these trace metals was carried out in unstirred and undeoxygenated solutions exhibiting sub-μg L⁻¹ limits of detection and enhanced analytical characteristics compared to conventional bismuth-film electrodes.     

Homogeneous Platinum‐Deposited Screen‐Printed Edge Band Ultramicroelectrodes for Amperometric Sensing of Carbon Monoxide

We report here the fabrication and application of an electrochemical carbon monoxide (CO) gas sensor based on the deposition of Pt nanoparticles on a screen‐printed edge band ultramicroelectrode (SPUME) with Nafion as the solid polymer electrolyte. Homogeneous size and distribution of Pt nanoparticles is stably deposited on the SPUME without either protective or capped agents. The edge diffusion effect at the SPUME, to even out the generation rate of hydrogen and to speed up the mass transfer of Pt solution, is believed to play a key role in achieving the deposition result. The obvious advantage of the proposed ultramicroelectrode system is that no supporting electrolyte (i.e., internal electrolyte) is required in the sensor scheme. The current–time curve recorded under conditions of +0.45 V vs. pseudo Ag reference electrode and various CO concentrations suggests that current response depends linearly on CO concentration up to 1000 ppm (correlation coefficient=0.994) with a sensitivity of 3.76 nA/(ppm?cm²). This report demonstrates potential application of the disposable CO gas sensor.     

A novel Au–Ag–Pt three-electrode microchip sensing platform for chromium(VI) determination

A simple, rapid and portable electrochemical microchip sensing platform has been successfully constructed for chromium(VI) determination. Gold–silver–platinum (Au–Ag–Pt) three-material electrodes (gold as working electrode, silver as reference electrode and platinum as counter electrode) were integrated on one poly(methyl methacrylate) (PMMA) substrate by polymer compatible photolithography process. The three-electrode microchip sensing platform was used for Cr(VI) determination for the first time, and exhibited high sensitivity and good reproducibility. A wide linear range from 2 to 200 μM with a good linear correlation (R² = 0.998) was obtained, and the detection limit was 0.9 μM. In addition, the practical analytical application of the sensing micro-platform was assessed by determination of Cr(VI) in real water samples with satisfactory results. Armed with the remarkable advantages, such as ease of use, low analyte consumption, inexpensive cost and fast response time, the microchip sensing platform may hold great potential for the high-throughput and in-field environmental monitoring Cr(VI) pollutant.     

TiO2薄膜光电极能带结构和催化活性的初探

以阳极氧化法制得的TiO₂薄膜光电极为工作电极,铂环为对电极,饱和甘汞电极为参比电极,组成光电催化降解苯酚体系.运用电化学阻抗图谱(EIS),测得光电催化过程中TiO₂薄膜光电极的空间电荷层电容,计算出半导体能带结构参数——空间电荷层宽度W.结果证明:当空间电荷层宽度W随阳极偏压增加而增大时,TiO₂薄膜电极光催化活性提高;当其等于薄膜厚度时,光催化活性最好,此时出现最佳偏压值;继续增加偏压,活性反而有所下降.     

Design of novel,simple, and inexpensive 3D printing-based miniaturized electrochemical platform containing embedded disposable detector for analytical applications

This paper describes the development of a novel, simple, and inexpensive electrochemical device containing an integrated and disposable three-electrode system for detection. The base of this platform consists on a PDMS structure containing microchannels which were prototyped using 3D-printed molds. Pencil graphite leads were inserted into these microchannels and utilized as working, counter and reference electrodes in a novel design. Morphological analysis and electrochemical experiments with benchmark redox probes were carried out in order to evaluate the performance and characterize the miniaturized device proposed. Even using inexpensive materials and a simple fabrication protocol, the electrochemical platform developed provided good repeatability and reproducibility over a low cost (ca. $2 per device), acceptable lifetime (ca. 250 voltammetric runs) and extremely reduced consumption of samples and reagents (order of µL). As proof of concept, the analytical feasibility of the platform was investigated through the simultaneous determination of dopamine (DOPA) and acetaminophen (AC). The two analytes showed linear dependence on the concentration range from 1 to 15 µM and the LODs achieved were 0.21 µM for DOPA and 0.29 µM for AC. Moreover, the platform was successfully applied on the determination of DOPA and AC in spiked blood serum and urine samples. The results obtained with the device described here were better than some reports in literature that use more costly electrodic materials and complex modification steps for the detection of the same analytes.     

Electrochemical urea biosensor based on Proteus mirabilis urease immobilized over polyaniline PANi-Glassy carbon electrode

In this study, a novel, sensitive electrochemical enzyme-based biosensor for urea detection was presented. This biosensor combines a three-electrode system consisting of a classic Glassy Carbon Electrode (GCE) as the working electrode, a platinum counter electrode, and Ag/AgCl as the reference electrode. To construct this urea platform, a GCE was modified with a polyaniline (PANi) film. Then, bacterial urease from Proteus mirabilis was immobilized on the modified GCE (P_m-Urease-PANi-GCE). For the characterization of surface modification, Cyclic Voltammetry (CV) and Scanning Electron Microscope (SEM) were applied, while the Square Wave Voltammetry (SWV) technique was performed for urea detection. The main analytical characteristics of the P_m-Urease-PANi-GCE biosensor showed a good linear range from 0.1 to 10 mM of urea, a limit of detection (LOD) of 0.1 mM, a Michaelis-Menten K_m of 0.23 mM, and a sensitivity value 46 μA/mM/cm². This biosensor allows the detection of urea in solutions, and it could be improved for further medical, environmental, or engineering applications.     

Solid-state reference electrodes for potentiometric sensors

The availability and application of solid-state reference electrodes for potentiometric electrochemical sensors are briefly reviewed. For a long time, considerable efforts have been made to combine solid-state indicator electrodes with equivalent reference electrodes to take advantage of the absence of liquid system components to full capacity. In spite of various suggestions to solve the problem, no type of solid-state reference electrode is so far available with properties completely identical to conventional ones.     

Electrochemical detection on electrowetting-on-dielectric digital microfluidic chip

In this work, the use of three-electrode electrochemical sensing system with an electrowetting-on-dielectric (EWOD) digital microfluidic device is reported for quantitative analysis of iodide. T-junction EWOD mixer device was designed using arrays of 50-μm spaced square electrodes for mixing buffer reagent and analyte droplets. For fabrication of EWOD chips, 5-μm thick silver EWOD electrodes were formed on a glass substrate by means of sputtering and lift-off process. PDMS and Teflon thin films were then coated on the electrodes by spin coating to yield hydrophobic surface. An external three-electrode system consisting of Au working, Ag reference and Pt auxiliary wires were installed over EWOD electrodes at the end of T-junction mixer. In experiment, a few-microliter droplets of Tris buffer and iodide solutions were moved toward the mixing junction and transported toward electrochemical electrodes by EWOD process. A short processing time within seconds was achieved at EWOD applied voltage of 300 V. The analyte droplets mixed with different concentrations were successfully analyzed by cyclic voltametry. Therefore, the combination of EWOD digital microfluidic and electrochemical sensing system has successfully been demonstrated for rapid chemical analysis with minimal reagent consumption.     

电位调控的“离子印迹”聚苯胺电极柱在阴离子分析中的应用

以氯离子为掺杂阴离子,采用化学氧化法合成了聚苯胺(PAn).将PAn作为导电固定相填充到多孔陶瓷管中以制备PAn电极柱,并以此电极柱作为三电极体系中的工作电极.在电极柱上施加0.6V的负电位使PAn呈还原态,PAn中掺杂的氯离子发生脱掺杂,从而在PAn骨架上留下在三维空间上与氯离子完全匹配的空穴,即形成了“离子印迹”P...     

Dynamic reference electrode for investigation of fluoride melts containing beryllium difluoride

Existing designs of reference electrodes for potentiometric measurements in fluoride melts do not meet basic requirements of the long exposure corrosion tests to be performed. A new diaphragm-free three-electrode meter with a nonstationary (dynamic) beryllium reference electrode for the redox potential measurements was developed. Optimum conditions of forming dynamic beryllium reference electrode were determined in the laboratory tests in isothermal cell. The device for redox potential measurement was designed and it was shown that it is highly sensitive to changes redox potential within ±5 mV. Reliability and efficiency of diaphragm-free device with dynamic reference electrode was confirmed in the thermal convection corrosion loop operating more than 1200 h with molten 15LiF-58NaF-27BeF₂ mixture (mol%) at a maximum temperature of about 700 °C.     

A new fabrication process for a microchip electrophoresis device integrated with a three-electrode electrochemical detector

We report here a novel and simple process for the fabrication of a poly(methyl methacrylate) (PMMA)-based microchip electrophoresis device, integrated with a screen-printed three-electrode electrochemical detector that does not require a replicate mold. In this approach, a photoresist layer constitutes both an adhesion layer and side walls of 50 mum wide and 50 mum tall microfluidic channels on a screen-printed three-electrode PMMA substrate. Openings were drilled for buffer reservoirs on an additional piece of PMMA, then the final device was bonded in a PMMA/photoresist/PMMA sandwich configuration. This process is inexpensive, less time-consuming, and simpler compared with traditional fabrication methods. The combination of this PMMA-based microchip fabrication together with screen-printed electrode technology holds great promise for the mass production of a single-use micrototal analytical system. Successful determination of uric acid and L-ascorbic acid with the presented system validates its utility. In combination with a suitable electrochemical detector, this device holds much promise for the determination of other analytes in various biological samples for medical and clinical diagnosis.     

一种铂网栅薄层光谱电化学池的制作及表征

以铂网栅电极作工作电极,设计制作了一种应用于紫外-可见光谱电化学研究的新型光透薄层电化学池（OTTLE）,并以铁氰化钾-亚铁氰化钾体系对此光谱化学池进行了表征。铁氰化钾-亚铁氰化钾体系在该池中有良好的循环伏安特性,并可获得良好的紫外-可见光谱。测得的克式量电位E^0,电子转移数n与文献结果一致。     

3‐D Nanoporous Pt Electrode Prepared by a 2‐D UPD Monolayer Process

A simple yet effective way is described to fabricate a nanostructured platinum electrode with extra high surface area. The fabrication process is the combination of the UPD monolayer and galvanic displacement in one electrochemical process and it is conducted in one medium and at the ambient temperature without using any toxic or corrosive electrolytes. The porous structure and roughness factor of the nanostructured Pt film can be controlled with the sweeping cycle of cyclic voltammetry (CV) easily. The nanoporous Pt deposit can enhance the response of the detection of glucose significantly and selectively without any enzyme incorporation. It is demonstrated that the nanostructured Pt film serves as a new electrode material in the application of nonenzymatic glucose detection.     

Disposable mercury-free cell-on-a-chip devices with integrated microfabricated electrodes for the determination of trace nickel(II) by adsorptive stripping voltammetry

This work reports the fabrication of disposable three-electrode cells with integrated sputtered metal-film electrodes. The working electrode was a bismuth-film electrode (BiFE) while the reference and counter electrodes were made of Ag and Pt, respectively. The deposition of the metal layers was carried out by sputtering of the respective metals on a silicon substrate while the exact geometry of the electrodes was defined via a metal mask placed on the substrate during the deposition process. Initially, the electrodes were characterised by cyclic voltammetry. The utility of these devices was tested for the trace determination of Ni(II) by square wave adsorptive stripping voltammetry (SWAdSV) after complexation with dimethylglyoxime (DMG). The experimental variables (the presence of oxygen, the DMG concentration, the preconcentration potential, the accumulation time and the SW parameters), as well as potential interferences, were investigated. Using the selected conditions, the 3sigma limit of detection was 100 ng L(-1) for Ni(II) (for 90 s of preconcentration) and the relative standard deviation for Ni(II) was 2.3% at the 10 microg L(-1) level (n=8). Finally, the method was applied to the determination of Ni(II) in a certified river water sample.