新型高温、长寿命氯化物熔盐参比电极的制备与研究

本文介绍一种全固态离子导电玻璃盐桥制备方法,并以此设计新型的Ag/AgCl高温参比电极.该电极制作简单, 具有电位稳定,重现性好,使用寿命长,不污染研究体系等特点.可在多种氯化物熔盐体系中反复使用,适用温度范围 400~900℃.     

Ag/AgCl/BiOIO_3三元复合物光催化剂的性能增强机制（英文）

半导体光催化技术是一种环境友好技术,它既能在温和条件下应用于环境领域——利用光能降解有机和无机污染物,又可应用于能源领域——将低密度的太阳能转化为高密度的洁净能源,因而在解决环境污染和能源匮乏问题方面展现出巨大的应用潜力.最近,一种新型Bi基光催化剂,Bi OIO3,表现出优异的紫外光催化性能.它由层状[Bi2O2]2+和[IO3]-组装而成,带隙为3.1 e V左右.然而,其较大的带隙限制了其对太阳光的利用.近年来,多种方法如金属掺杂、非金属掺杂、半导体复合、光敏化改性和加氢处理被用来提高半导体的光催化效率.其中,以Ag/AgX(X=Cl,I和Br)作为助催化剂可提高体系的可见光吸收和载流子的分离能力,从而增强光催化性能.基于此,我们设计并合成了一种新型的三元光催化剂.首先采用水热法合成了Bi OIO3纳米片,然后在室温条件下原位引进Ag/Ag Cl,制备了Ag/Ag Cl/Bi OIO3三元异质结构.与Ag/Ag Cl和纯的Bi OIO3相比,该三元Ag/Ag Cl/Bi OIO3复合物光催化剂对NO表现出优异的可见光光催化去除性能.本文采用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描式电子显微镜(SEM)、电化学测试(光电流和阻抗谱)和紫外-可见漫反射光谱(UV-Vis)等表征手段研究了Ag/Ag Cl/Bi OIO3光催化性能增强的机制.SEM结果表明,制备的Ag/Ag Cl/Bi OIO3三元复合物为纳米颗粒和纳米片形貌,Ag/AgC l的引入对Bi OIO3形貌影响不大.XRD和XPS测试结果表明,与纯的Bi OIO3相比,随着Ag/AgC l的加入,复合物的峰位置发生了明显位移,表明Ag,AgC l和Bi OIO3三组分间存在强的相互作用.光电流响应图谱表明,随着Ag/Ag Cl的加入,Ag/Ag Cl/Bi OIO3的光电流强度明显增强,同时阻抗谱的圆弧直径明显减小,表明电子和空穴的分离能力增强.UV-Vis图谱中,Bi OIO3在可见光区几乎没有吸收,而三元复合物表现出明显的可见光吸收,且随着Ag/AgC l量的增加,复合物的可见光吸收增强,该吸收归结于复合物中Ag的表面等离子体吸收.结合之前报道的光催化剂体系如Ag/Ag Cl和Ag/Ag Cl/Ti O2,我们提出了Ag/Ag Cl/Bi OIO3复合物光催化剂性能增强的机制.在可见光照射下,Ag0因其表面等离子体吸收而产生电子空穴对.由于功函数不同,Ag和Bi OIO3之间形成肖特基势垒.电子从Ag0表面转移到Bi OIO3的导带上,Bi OIO3导带上电子的电势不足以把O2氧化成·O-2,但电子能以多电子的形式与O2和H+生成水.同时,Ag0表面的空穴能将AgC l表面的Cl-氧化成Cl0.光照诱导AgC l表面的部分Ag+离子被还原,所以AgC l粒子的表面带负电荷.Cl0是活性自由基,能够氧化去除NO,反应之后自身被还原成Cl-.由此可见,在三元复合光催化剂中,Ag0在可见光照射下因其表面等离子体效应产生电子空穴对,随后Bi OIO3有效地分离了光生载流子,使得复合材料能有效地利用光生电子和空穴.故三元Ag/Ag Cl/Bi OIO3复合物光催化剂增强的光催化性能可归结于Ag的表面等离子体吸收和Bi OIO3的载流子分离能力.该结果有助于设计和制备具有优异的光催化性能的Bi OIO3基材料.     

以纳米Ag与接枝酪蛋白为复合载体的葡萄糖氧化酶电极的研究

采用电化学方法从AgNO3 的柠檬酸水溶液中制备纳米Ag,并用激光光散射粒度分析仪和X_衍射仪对其粒径和形态进行了表征。以纳米Ag和接枝酪蛋白为复合载体制备了葡萄糖氧化酶电极, 研究了工作电位、底物浓度、温度、溶液pH对电极电化学响应特性的影响,以及电极的专一性和重现性实验。结果表明:制备的Ag粒子的粒径约为40 nm, 近似球形, 存在着一定的硬团聚; 该复合酶电极的线性响应范围为1.0×10-6~1.5×10-2 mol/L,响应时间仅为12 s, 并具有优良的重现性和高选择性。     

异质结构AgCl/Bi_2WO_6微米球制备、表征及其光催化性能（英文）

首先利用水热法制备了由纳米片组装的粒径为1.5–2μm的Bi2WO6微球,然后在微球表面沉积了不同含量的AgC l(5 wt%,10 wt%,20 wt%,30 wt%),制备了异质结构Ag Cl/Bi2WO6微球光催化剂.利用X射线粉末衍射、扫描电镜、透射电镜、红外光谱、紫外-可见漫反射吸收等手段对所制的光催化剂进行表征,并以紫外光和可见光分别为光源,罗丹明B为降解对象测试了其光催化活性,考察复合不同含量的AgC l对Bi2WO6光催化剂的性能影响.结果表明,沉积AgC l对Bi2WO6的晶体结构、表面性能和光吸收性能没有产生明显影响,但大幅度提高了Bi2WO6的紫外和可见光催化活性.当复合20 wt%Ag Cl时,AgC l/Bi2WO6光催化活性最佳,紫外光下比纯Bi2WO6提高了2.2倍,可见光下提高了1倍.这主要是由于形成的Ag Cl/Bi2WO6异质结能有效抑制光生电子和空穴的复合,从而提了其光催化性能.     

Nafion修饰Ag/AgCl参比电极的研制及其在pH电化学传感器中的应用

制备了Nafion修饰的Ag/AgCl参比电极,参比电极电位(25℃)为-47.5±1mV,制备的电极有良好的重现性,电极电位不受溶液pH值和Cl-浓度变化的影响,有良好的抗S2-I、-离子干扰能力,且有较好的抗脉冲电流干扰能力。该参比电极适用于间歇式测试场合,可以保证稳定的参比电位;可用于基于W氧化物pH电极的电化学传感器,传感器的内阻为22kΩ,小于玻璃pH电极计内阻(1~10MΩ)。     

表面等离子体波共振技术应用于气体检测

本文简要介绍了表面等离子体波共振技术的基本原理,重点综述了该技术在气体检测研究中的应用。被检测的气体包括：常见的易燃易爆和有毒气体、有机气体及蒸汽等。通过敏感膜材料的选择和优化、检测装置的改进、制膜方式和工艺条件、薄膜厚度的调整,来提高检测结果的灵敏度、选择性、可逆性、响应时间、脱附时间和重现性等重要参数。将表面等离子体波共振技术和其它技术联用可以在提高检测灵敏度的同时,实现对气体的远程监测。 主要介绍了此技术和光纤技术的联用,此外还讨论了环境特别是湿度和温度对检测结果的影响。     

肌红蛋白-壳聚糖-金胶纳米复合修饰电极的电催化

在pH 5.4的HAc-NaAc缓冲溶液中,肌红蛋白-壳聚糖-金胶薄膜修饰电极(Mb-Ch itosan-Au colloid/GCE)于-0.20 V(vs.Ag/AgC l)处有一对准可逆的氧化还原峰,即Mb血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰.本实验条件下,肌红蛋白与玻碳电极之间的电子传递明显加快,并考察了扫速、溶液pH及支持电解质浓度等因素对肌红蛋白电子传递的影响.紫外光谱图表明:肌红蛋白在壳聚糖-金胶溶液中依然保持其原始构象.该肌红蛋白-壳聚糖-金胶纳米修饰电极还能电催化溶解氧的还原.     

管状流通式阴离子表面活性剂电极的研制

以石墨管为基体,十六烷基三甲基溴化铵为电活性物质,制备了带有内参比电极(Ag/AgC l)的管状流通式阴离子表面活性剂选择性电极,对其性能进行了测试。实验结果表明,其线性响应范围为1.6×10-7~5.1×10-3mol/L,斜率为52.0 mV/dec,检出限为2.0×10-8mol/L。利用该电极进行测试时,常用的无机阴离子C l-、SO42-、NO3-、PO43-等不会对其产生干扰;该电极适宜的pH值范围为2.50~10.50。对水样测定,回收率为95%~104%。电极可连续使用50 d左右。     

肌红蛋白-纳米氧化铝模板-金胶复合组装体的直接电化学与电催化

将肌红蛋白(Mb)固定在纳米氧化铝(AAO)模板-金胶复合组装体修饰玻碳电极表面,制得Mb/AAO/Au colloid/GC薄膜电极.在pH=5.4的HAc-NaAc缓冲溶液中,该薄膜电极于-0.21 V(vs.Ag/AgC l)处有一对准可逆的氧化还原峰,为Mb血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰.在AAO/Au colloid薄膜的微环境中,Mb与玻碳电极间的电子传递明显加快,该Mb/AAO/Au colloid/GC薄膜电极还可用于过氧化氢和溶解氧的催化还原.     

光波导乙醇气体传感器的研究

以聚偏氟乙烯(PVDF)作为敏感试剂固定在钾(K⁺)离子交换玻璃光波导表面,研制了光波导乙醇气体传感器.该传感器具有可逆性好、灵敏度高、响应速度快、选择性和重现性好、能在室温操作等特点.     

The fabrication and performance of an Ag/AgCl reference electrode in human serum

A simple set of electric circuits was used to assemble a pulse generator. With pulse potentials and under galvanostatical control, a clean silver wire was anodized electrochemically for 0.2–0.5 min in 1.0 mol l⁻¹ HCl with a pulse current density of 20 mA cm⁻², and the pulse wave parameters of t_a/t_c = 1 and a cycle of 4 s forming an Ag/AgCl reference electrode. Even though the AgCl layer was consumed during the working period when the Ag/AgCl electrode was used as a cathode, the AgCl layer could be in situ recovered electrochemically in serum used when a reversed potential was applied to the electrode system immediately after the measuring program was finished. The current response curve of the anode indicated that an AgCl layer in high density was basically accomplished during the first 6 pulse cycles in human serum. In order to keep a stable and uniform AgCl layer on the reference electrode after each measuring cycle, the ratio of the recovery time (t_r) to the working time (t_w) was measured and the smallest value was obtained at 0.03. The open-circuit potential of the Ag/AgCl electrode with respect to a SCE in 0.1 mol l⁻¹ KCl was monitored over a period of 14 days and the mean value was 40.09 mV vs SCE with a standard deviation of 2.55 mV. The potential of the Ag/AgCl reference electrode did remain constant when the measurements were repeated more than 600 times in undiluted human serum with a standard deviation of 1.89 mV. This study indicated that the Ag/AgCl reference electrode could been rapidly fabricated with a pulse potential and could be used as a reference electrode with long-term stable properties in human serum samples.     

An Arrayed Micro‐glutamate Sensor Probe Integrated with On‐probe Ag/AgCl Reference and Counter Electrodes

Complete all‐in‐one multi‐arrayed glutamate (Glut) sensors have been constructed on a silicon‐based micromachined probe composed of micro‐platinum (Pt) working electrodes, a micro‐silver/silver chloride (Ag/AgCl) reference electrode (RE), and a micro‐Pt counter electrode (CE). The OCP shift of the electrodeposited Ag/AgCl on‐probe micro‐reference electrode compared with a Ag/AgCl wire is <0.1 mV/h. The composition ratio of Ag, Cl, and Pt on the electrodeposited on‐probe micro‐reference electrode is observed to be 1.00 : 0.48 : 0.02 analyzed by EDS. The miniaturized amperometric Glut biosensors were constructed on working electrode sites (electrode area: ∼8.5×10⁻⁵ cm²) of the microprobe modified with glutamate oxidase (GlutOx) enzyme layers for the selective, fast, and continuous detection of L‐glutamate. The sensor selectivity towards common electroactive interferents has been improved significantly by coating the electrode surface with perm‐selective polymer layers, overoxidized polypyrrole (PPY) and Nafion®. The sensitivity, detection range, and response time of the proposed all‐in‐one Glut biosensors are 204.7±5.8 nA μM⁻¹ cm⁻² (N=5), 4.99–109 μM, and 2.7±0.3 sec, respectively and no interferent signals of AA and DA were observed. The sensor can be reused over 19 times of continuous repetitive operation (total measurement time: ∼4 hours) and the sensor sensitivity can retain up to four weeks of storage.     

Construction and Application of a PVC Membrane Enoxacin Ion－selective Electrode Based on a Needle－shaped Inner Reference Electrode

IntroductionPVC membrane- coated- wire electrodes areused in the analytical field widely. They are pre-pared usually with platinum wire,silver wire orgraphite rod coated with a PVC thin membranecontaining various active components and plasticiz-ers[1— 3 ] .The electrodes have no inner KCl solutionand they are notinfluenced by the sample pressure.Furthermore,they are free from directional selec-tivity when they are installed,and they can be mi-crominiaturized easily. The shortcomings of th…     

No more conventional reference electrode: Transition time for determining chloride ion concentration

Ion selective electrodes (ISE) are used extensively for the potentiometric determination of ion concentrations in electrolytes. However, the inherent drift in these measurements and the requirement of a stable reference electrode restrict the feasibility of this method for long-term in-situ applications. This work presents a chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode for measuring chloride ion concentration. An anodic current pulse is applied to a Ag/AgCl working electrode which initiates a faradaic reaction that depletes the chloride ions near the electrode surface. The rate of change in potential at the Ag/AgCl electrode, due to chloride ion depletion, reaches an inflection point once the chloride ions deplete completely near the electrode surface. The moment of the inflection point, also known as the transition time, is a function of the chloride ion concentration and is described by the Sand equation. It is shown that the square root of the transition time is linearly proportional to the chloride ion concentration. Drift in the response over two weeks is negligible: 59 μM/day when measuring 1 mM of Cl⁻ ions using a 10 A m⁻² current pulse. The transition time at a specific ion concentration can be tuned by the applied current pulse, e.g., in a solution containing 5 mM chloride ions, the transition times with current pulses of 10 and 20 A m⁻² are 1.56 and 0.25 s, respectively. The moment of inflection determines the response, and thus is independent of the absolute potential of reference electrode. Therefore, any metal wire can act as a pseudo-reference electrode, enabling this approach for long-term and integrated-sensor applications such as measurement inside concrete structures.     

Screen-printed reference electrodes for potentiometric measurements

A convenient and reliable method for large-scale production of miniaturized, planar, all-solid-state reference electrodes is reported. All elements of the Ag/AgCl/KCl reference half-cell i.e. layer of Ag/AgCl (inner electrode), immobilized electrolyte (junction) and encapsulation are fabricated by means of screen-printing technology. The use of pastes cured in low temperature allows fabrication on low-cost, plastic, flexible foils. The developed reference electrodes exhibit good long-term stability. Continuous operation life-time exceeds one week. Storage stability is longer than 9 months. pH, chlorides as well as other halide anions, typical buffer components, alkaline and heavy metal cations, complexing ligands and redox agents, do not influence the potential of the reference electrodes. The developed reference electrodes are compatible with strip potentiometric sensors fabricated in the same format. Examples of analytical applications of the reference electrodes with various screen-printed sensors are demonstrated.     

一种全固态扑尔敏电极的研制

制备了以脲醛树脂为框架，以ＫＣｌ粉末为活性组分的Ａｇ／ＡｇＣｌ固体电极。结果表明该电极具有相当好的稳定性并能用于扑尔敏制剂的含量测定。     

Flow injection analysis of doxycycline or chlortetracycline in pharmaceutical formulations with pulsed amperometric detection

A flow injection with pulsed amperometric detection for determination of doxycycline or chlortetracycline in pharmaceutical formulations is described. Doxycycline or chlortetracycline were studied at a gold rotating disk electrode with cyclic voltammetry as a function of pH of supporting electrolyte solution. The optimized PAD waveform parameters were obtained with a flow injection system. The optimized pulsed conditions of doxycycline were 1150 mV (versus Ag/AgCl reference electrode) detection potential (E_det) for 220 ms (150 ms delay time and 70 ms integration time), 1500 mV (versus Ag/AgCl reference electrode) oxidation potential (E_oxd) for 70 ms oxidation time (t_oxd) and 250 mV (versus Ag/AgCl reference electrode) reduction potentail (E_red) for 400 ms reactivation time (t_red). The optimized pulsed conditions of chlortetracycline were 1050 mV (versus Ag/AgCl reference electrode) detection potential (E_det) for 300 ms (200 ms delay time and 100 ms integration time), 1300 mV (versus Ag/AgCl reference electrode) oxidation potential (E_oxd) for 70 ms oxidation time (t_oxd) and 250 mV (versus Ag/AgCl reference electrode) reduction potentail (E_red) for 400 ms reactivation time (t_red). The optimized PAD waveform was applied to the determination of doxycycline hydrochloride and chlortetracycline hydrochloride standard solution and in pharmaceutical formulations. The linear dynamic ranges of doxycycline hydrochloride and chlortetracycline hydrochloride were 1 μM–0.1 mM. The sensitivity of this method was found to be 23 μA/mM for doxycycline hydrochloride and 33.76 μA/mM for chlortetracycline hydrochloride. The detection limit for both compounds is 1 μM. The doxycycline hydrochloride and chlortetracycline hydrochloride content in commercially available tablet dosage forms by the proposed method was comparable to those specified by the manufacturer.     

Studies of the chlorpheniramine solid-state ion-selective electrode

An Ag/AgCl solid-state electrode was prepared by using urea-formaldehyde resin as the frame material and KCl powder as the active material. Using the prepared Ag/AgCl solid-state electrode as substrate and chlorpheniramine tetraphenylborate ion-pair complex as the active component, a new type of solid-state chlorpheniramine ion-selective electrode was constructed. The properties of the electrode were studied in detail. The electrode shows a rather good stability and can be used in the potentiometric determination of chlorpheniramine.     

Effect of anode materials on the characteristics of the miniature Clark-type oxygen electrode

A miniature Clark-type oxygen electrode was fabricated using semiconductor techniques. A two-electrode configuration was used and the effect of different anode materials on the characteristics of the oxygen electrode was examined. The cathode and anode were formed in anisotropically etched grooves and calcium alginate gel containing 0.1 M KCl electrolyte filled the grooves. A gas-permeable membrane was directly formed over the gel. By using an Ag/AgCl anode instead of a gold electrode, the response time was shortened, the residual current was decreased and the linearity of the calibration graph was improved. Good linear calibration graphs were obtained by using the Ag/AgCl anode. The Ag/AgCl anode oxygen electrode produced a stable current for 5 h at ?0.8 V and for 22 h at ?0.6 V.     

Reference Electrodes in Dimethylformamide

Abstract

An investigation of an Ag/Ag⁺ reference electrode in dimethylformamide solution is reported. Simple preparation, fast response and high exchange current density characterize this reference electrode. The stability of the electrode with time and its temperature coefficient were also studied.