Iridium Oxide Film Electrodes for Anodic Stripping Voltammetry

The new iridium oxide film electrode, applied for the determination of lead(II), cadmium(II) and copper(II) traces using differential pulse anodic stripping voltammetry (DP ASV) is presented. The electrode display an interesting stripping voltammetric performance which compares with electrodes commonly used in voltammetry. The deposited film is known as anodically electrodeposited iridium oxide film (AEIROF). The AEIROF electrode is characterized by long‐term stability (more than 40 days) and very good reproducibility of the analytical signals in this time (≤12% for 0.5 μM of lead). The regeneration of iridium film is very simple in a time shorter than 60 seconds. The effects of various factors such as: thickness of AEIROF film, preconcentration potential and time, supporting electrolyte composition, potential interferences are optimized. The detection limit for AEIROF film electrode based on glassy carbon for an accumulation time of 30 s is as low as 7 nM for lead(II). The repeatability of the method at a concentration level of the lead(II) as low as 0.5 μM, expressed as RSD is 2.5% (n=10). The proposed method was successfully applied and validated by studying certified reference material CTA‐OTL‐1. Such an attractive use of ‘mercury–free’ ‐ environmentally friendly electrodes offers great promise to measure trace metals.     

钛基氧化铱电极电沉积制备技术研究进展

钛基氧化铱电极作为DSA(dimension stable anode)中的典型电极,广泛应用于各个领域.目前工业生产的钛基氧化铱电极主要由传统热分解法制备,存在成本高昂,工艺繁琐,依赖人工劳动,无法大规模生产等问题,十分有必要探索开发新的制备技术.本文从沉积液配方、基底材料的选择及处理、电沉积方式以及沉积时间等方面系...     

硫酸对壳聚糖膜分离性能影响的本质

近年来,强酸性溶液中析氧电极的研究逐渐受到重视,如：电冶金生产Ｃｕ、Ｚｎ、Ｃｏ等都用到此类电极．传统的尺寸稳定性阳极—含钌阳极的涂层在强酸环境中容易与Ｏ２作用生成可溶的ＲｕＯ４使涂层迅速失活．ＩｒＯ２Ｔａ２Ｏ５涂层是目前公认的具有良好电催化性能和化...     

量子点发光二极管中电荷累积行为

量子点发光二极管(QLED)是不需要额外光源的主动发光技术,在显示领域中的应用前景被广泛看好。寿命较短是影响QLED商业化的重要因素之一,并且其老化机理尚不清晰。在本工作中,我们通过自主搭建电荷提取装置,证实红光QLED在恒流驱动过程中,存在显著的电荷累积。累积电荷量随着驱动电流密度增加而增加,但当超过阈值电流密度(对应于开启电压)后逐渐趋于饱和。随着器件老化,亮度下降伴随着累积电荷量进一步增加。本工作对QLED老化过程中电荷累积规律的理解,能为QLED材料和界面的优化设计提供直观判据。     

Studies of Laser-induced-MOCVDZinc Oxide Films

ＳｔｕｄｉｅｓｏｆＬａｓｅｒ－ｉｎｄｕｃｅｄ－ＭＯＣＶＤＺｉｎｃＯｘｉｄｅＦｉｌｍｓＲＥＮＰｅｎｇ－ｃｈｅｎｇ，ＴＡＮＺｈｏｎｇ－ｋｅａｎｄＬＵＯＷｅｎ－ｘｉｕ（ＣｅｉｉｔｅｒｆｏｒＦｕｎｃｔｉｏｎａｌＭａｔｅｒｉａｌｓＲｅｓｅａｒｃｈ，Ｑｉｎｇｄａ...     

钛表面二氧化钛膜中氧空位点缺陷传输性能的电化学研究

"钛/TiO2氧化膜/溶液"界面电极体系的电化学性能主要决定于钛表面的TiO2氧化物膜.本文利用多种电化学技术,结合半导体物理的Mott-Schottky分析和Einstein方程,研究了金属钛在1.0mol·L-1HClO4溶液中表面半导体TiO2氧化膜的生长及氧化膜中氧空位点缺陷在外加电场作用下的传输性能,并根据离子性电荷传输与电子性电荷传输对电场变化响应时间之不同特点,确定氧化膜中点缺陷扩散系数.结果表明,电极电位或阳极析氧反应对稳态电流(iss)、氧化膜的阳极化常数(α)、膜中电场强度()、以及膜中氧空位点缺陷的扩散系数(D0)等重要物理化学参数,均有显著影响,并依据氧化膜中的结构变化进行分析.     

Insights into the Oxidative Dehydrogenation of Amines with Nanoparticulate Iridium Oxide

The aerobic oxidation of amines offers a promising route towards many versatile chemical compounds. Within this contribution, we extend our previous investigations of iridium oxide‐catalyzed alcohol oxidation to amine substrates. In addition to demonstrating the versatility of this catalyst, particular attention is focused on the mechanisms of the reaction. Herein, we demonstrate that although amines are oxidized slower than the corresponding alcohols, the catalyst has a preference for amine substrates, and oxidizes various amines at turnover frequencies greater than other systems found in the open literature. Furthermore, the competition between double amine dehydrogenation, to yield the corresponding nitrile, and amine–imine coupling, to yield the corresponding coupled imine, has been found to arise from a competitive reaction pathway, and stems from an effect of substrate‐to‐metal ratio. Finally, the mechanism responsible for the formation of N‐benzylidene‐1‐phenylmethanamine was examined, and attributed to the coupling of free benzyl amine substrate and benzaldehyde, formed in situ through hydrolysis of the primary reaction product, benzyl imine.     

Iridium Oxide Film-Enhanced Impedance Immunosensor for Rapid Detection of Carcinoembyronic Antigen

A simple, rapid and sensitive impedance immunosensor based on iridium oxide （IrOx） thin film for the detection of carcinoembyronic antigen （CEA） in human sera has been proposed. Gold electrode was electrochemically modified with IrOx thin film and simultaneously functionalized with protein A （PA） to bind anti-CEA antibodies in an orientated way. It has been found that the antibody loading amount was dependent on the PA concentration and the deposition time of IrOx matrix. Under the optimized experimental conditions, the electron transfer resistances obtained were linearly related to the CEA concentration ranging from 36.2 to 460.0 ng/mL, with a detection limit of 28.0 ng/mL. Analytical results of clinical samples from cancer patients show that the proposed immunoassay is reasonably comparable with the chemiluminescence immunoassay （CLIA）, indicating the feasibility of using the proposed method for CEA immunoassay in clinical laboratory.     

ZnO及其含锌混合氧化物薄膜的充放电性能研究

从充放电性能、晶体结构等方面考察了包括粉末状的ZnO、脉冲激光沉积方法制备的ZnO薄膜和含锌混合氧化物薄膜的电化学性质.结果表明,ZnO粉末制备的电极的嵌入容量随退火温度的升高而增大,掺入其他氧化物可以明显改善ZnO薄膜的电化学性能,在Ar气氛中,基片温度为400℃时,沉积的靶子成分为Zn:B:P:Al=1:1:0.5:0.5(摩尔比)的含锌混合氧化物薄膜具有较高的可逆容量,且循环性能良好.     

Sol-Gel Deposited Sb-Doped Tin Oxide Films

The structural, electrical and optical properties of single sol-gel derived antimony-doped tin oxide (ATO) films sintered at 550°C have been measured. The reproducibility of both the preparation and the characterization procedures have been tested by a round-robin test involving eight laboratories within a Concerted European Action (CEA) project. The resistivity measured as a function of Sb content has been obtained by electric and reflectance and transmission measurements. Their differences are discussed in terms of structural and grain boundary effects. An increase of Sb content results in a decrease of the crystallite size (7.0 to 5.4 nm) and a greater influence of the grain boundary.     

Chiral Thin Films of Metal Oxide

In this paper, we describe for the first time the synthesis of new chiral nanosized metal oxide surfaces based on chiral self‐assembled monolayers (SAMs) coated with metal oxide (TiO₂) nanolayers. In this new type of nanosize chiral surface, the metal oxide nanolayers enable the protection of the chiral self‐assembled monolayers while preserving their enantioselective nature. The chiral nature of the SAM/TiO₂ films was characterized by variety of unique techniques, such as second‐harmonic generation circular dichroism (SHG‐CD), quartz crystal microbalance, and chiral adsorption measurements with circular dichroism spectroscopy. The chiral resolution abilities of the SAMs coated with metal oxide (TiO₂) nanolayers were investigated in the crystallization of a racemic mixture of threonine and glutamic acid. Our proposed methodology for the preparation of nanoscale chiral surfaces described in this article could open up opportunities in other fields of chemistry, such as chiral catalysis.     

Developing an Iridium Oxide Film Modified Microelectrode for Microscale Measurement of pH

Iridium oxide film modified microelectrode was fabricated by anodic oxidation method onto the tip of an etched iridium wire in diluted sulfuric acid solution by cyclic voltammetry. The iridium oxide film microelectrode exhibited very promising pH sensing performance, with an ideal Nernstian in the tested pH range of 0 to 14. This method for preparing microelectrode allowed accurately control of the deposited amount and the rate of the iridium oxide film growth. The electrodes demonstrated advantages of long lifetime, good selectivity and fast response with a relative time less than 0.2 s for pH changes in a large scale. The microelectrode was not interfered by a wide variety of inorganic ions and organic compounds. Furthermore, the electrodes were successfully applied to the measurement of pH in microscale of apples.     

Electrical Properties of Transparent Doped Oxide Films

In the present study n-type and p-type transparent conductive TiO₂ films were prepared by using sol-gel method. The n-type TiO₂ films were obtained by using Ti(OC₃H ₇ ⁱ )₄ solutions co-doped with Ru and Ta. The films were uniform and transparent in all the conditions, and their crystalline phases were anatase when HCl or HNO₃ was used as a catalyst. The resistivity decreased with increasing Ta content and increased with increasing Ru content. Most of the films showed resistivity minima at a heat-treatment temperature of 700°C. The lowest resistivity of 10¹ 10² cm was attained. The p-type TiO₂ films were obtained by using Ti(OC₃H ₇ ⁱ )₄ solutions co-doped with Co and Nb (Sb). The films were also uniform and transparent when AcAc was used, while samples heat-treated at 800°C became opaque when HCl was added. Rutile single phase appeared when the films were heat-treated at 700°C. Logarithmic resistivity of films co-doped with Co and Nb was directly proportional to the reciprocal absolute temperature. On the other hand, the slopes for films co-doped with Co and Sb were different below and above 200°–220°C. The activation energy at the low-temperature region is as low as 0.17 eV, and the resistivity at room temperature is 10⁴ 10⁵ cm.     

Vapor-Gel Deposition Method for Oxide Thin Films

In this paper, we attempt to formally establish the chemistry of a vapor-gel process for the low temperature deposition of thin films. A number of applications of such a process will be discussed mostly on a theoretical basis, with the exception of one or two particular aspects that we have experimentally demonstrated so far. The essential components of the deposition apparatus will be described in detail along with some discussions on their operation conditions. Finally, we conclude this paper by systematically comparing the vapor-gel method to other well-known thin film fabrication techniques including the sol-gel method.     

Subsurface Space‐Charge Dopant Segregation to Compensate Surface Excess Charge in a Perovskite Oxide

Since the first prediction by Frenkel, many follow‐up studies have been carried out to show the presence of subsurface space‐charge layers having the opposite sign to that of the excess charge at the surface, producing overall neutrality in ionic crystals. However, no precise experimental evidence demonstrating how the aliovalent solutes segregate in the space‐charge region beneath the surface has been provided over the past several decades. By utilizing atomic‐scale imaging and chemical probing in a perovskite oxide, the origin of the surface excess charge at the topmost surface and the position of segregated dopants in the space‐charge region is precisely determined. The impact of the space‐charge contribution to the dopant distribution near the surface in oxide crystals is explored.     

锌铈混合金属氧化物薄膜电化学沉积的研究

采用自制四电极体系,原位测量锌铈混合氧化物薄膜电沉积过程电极/溶液界面pH的动态变化。电极/溶液界面的pH-时间曲线表明,pH快速上升后达到平衡,且电沉积过电位越大,达到平衡pH值的时间越短,平衡pH值也越高。X射线粉末衍射(XRD)实验证明薄膜沉积物是由ZnO和CeO2组成。电感耦合等离子体(ICP)技术分析了不同电沉积电位、不同电沉积时间下电沉积产物中Ce(Ⅲ)/Zn(Ⅱ)的物质的量比,结果表明Ce(Ⅲ)/Zn(Ⅱ)的物质的量比随着pH值的升高而增加。依据Zn2+离子和Ce3+离子液相和固相中存在形态的热力学数据,计算了2种金属离子的条件溶解度随pH的变化曲线。结合实验测试数据和理论计算结果,讨论了电极表面金属氧化物的电化学沉积机理,并阐明了阴极表面混合金属氧化物的组成取决于液-固两相中金属离子存在形态的热力学性质。     

Formation Efficiency of Porous Oxide Films in Aluminum Anodizing

Russian Journal of Electrochemistry - Anodic oxidation of aluminum in acidic electrolytes is widely used for the formation of porous oxide films with a regular structure on the metal surface....     

Nanocrystalline Manganese Iron Oxide as a Charge Storage Electrode

Phase pure nanocrystalline manganese iron oxide [(Mn_0.37Fe_0.63)₂O₃] was synthesized by combustion technique based on propellant chemistry principle employing citric acid as fuel. The synthesized powder was characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), BET, BJH analysis and electrochemical studies for possible application as a charge storage electrode. The average crystallite size was found to be 18.6 nm from XRD analysis. BET analysis yielded the surface area and specific pore volume of the powder to be 22.96 m² g^?1 and 0.0098 cm³ g^?1 respectively. The specific capacitance from cyclic voltammetric studies at scan rate 5 mV s^?1 was found to be about 30 F g^?1 cm^?2 while from charge discharge studies was found to be 27±1 F g^?1 cm^?2. In addition, the material showed appreciable stability during charge‐discharge cycling.     

Ultraviolet-Laser-Induced Crystallization of Sol-Gel Derived Indium Oxide Films

Modification of sol-gel derived indium oxide thin films using ultraviolet lasers was investigated. Irradiation by an ArF excimer (6.4 eV) and the fourth harmonic generation of a Nd : YAG laser (4.7 eV) was found to be effective in crystallization with a loss of hydroxyl groups and a decrease in the sheet resistance of the sol-gel films. Transparent crystalline indium oxide films were successfully obtained by 6.4 eV laser irradiation at fluences below 20 mJ/(cm2·shot), whereas degradation of the films was induced by a relatively high-fluence beam.     

Ultraviolet-Laser-Induced Crystallization of Sol-Gel Derived Inorganic Oxide Films

Structural changes stimulated by ultraviolet (UV) laser irradiations of sol-gel derived inorganic oxide films were investigated. Dried gel films of TiO₂, Nb₂O₅, Ta₂O₅, SrTiO₃ and Pb(Zr _x Ti_1–x )O₃ (PZT) were found to be crystallized by the laser irradiation. On the other hand, the photo-induced change in gel films of BaTiO₃, LiNbO₃ and LiTaO₃ was not observed although the laser beams were absorbed in the films. These sol-gel films were thermally crystallized at almost the same temperature around 600–700°C except TiO₂. Thus, the UV-laser-induced crystallization is not directly ascribed to a simple thermal effect with the irradiation. Photochemical properties of the cations are assumed to be important for the change in sol-gel films.