n-CdSe/Fe(CN)_6~(4~-/3~-)光阳极上的光氧化竞争反应及用L-B技术修饰电极的影响

用旋转环盘电极研究了还原剂K_4Fe(CN)_6与n-CdSe光阳极上的竞争空穴的氧化反应,证明还原剂捕获光生空穴的途径为直接自价带俘获空穴。又利用L-B技术在n-CdSe电极表面修饰硬脂酸二茂铁酯,结果表明还原剂俘获光生空穴的能力增强,电极的稳定系数提高。     

碳纳米管修饰玻碳电极的循环伏安实验的改进

循环伏安法是一种重要的电化学分析方法。本实验对铁氰化钾溶液的配制进行了摸索,得出5 mmol/L K_3Fe(CN)_6溶液(含5 mmol/L K_4Fe(CN)_6+0.1 mol/L KCl)时,电极的循环伏安图出峰效果最佳。对分散碳纳米管的溶剂进行改进,结果表明高纯水和有机溶剂溶解的碳纳米管,玻碳电极的修饰效果相差不大,故选择更安全环保的高纯水溶解碳纳米管。教学过程加深了学生对循环伏安法的理解,增强学生的绿色环保意识。     

锌钡白中硫化锌含量测定

一、概述以往用亚铁氰化钾测定锌钡白中ZnS,锌离子与亚铁氰化钾作用生成一种不溶于稀酸的白色沉淀: 3Zn~( 2) 2[Fe(CN)_6]~(-4) 2K~( 1)→K_2Zn_3(Fe(CN)_6]_2↓测定终点,采用(NH_4)_2MoO_4或UO_2(A     

铁镍双金属配合物[Fe(2,2’–bpy)_2Ni(CN)_4]_n的合成、晶体结构及磁性

使用K_3[Fe(CN)_6]提供氰基阴离子和Fe~(2+)阳离子,与Ni(Ac)_2·4H_2O和2,2’–联吡啶(2,2’–bpy)在水热条件下反应制备了氰基桥连的双金属铁镍配合物[Fe(2,2’–bpy)2Ni(CN)_4]_n(1),用红外光谱、热重分析和X射线衍射对其进行表征。结果表明:在配合物1中,[Fe(2,2’–bpy)_2]~(2+)阳离子和[Ni(CN)_4]~(2–)阴离子通过氰基桥联形成Fe~(2+)、Ni~(2+)离子交替存在的一维锯齿链[Fe(2,2’–bpy)_2Ni(CN)_4]_n,热重分析显示,双金属配合物[Fe(2,2’–bpy)_2Ni(CN)_4]_n有较好的热稳定性,磁性测量表明,配合物[Fe(2,2’–bpy)_2Ni(CN)_4]_n中金属铁镍离子间存在强的反铁磁相互作用。     

硬脂酸二茂铁酯L—B膜修饰SnO2电极的阻抗研究

测定了二茂铁衍生物——硬脂酸二茂铁酯L-B膜修饰SnO_2电极在Fe(CN)_6~(3-/4-)溶液中的阻抗性能,用单纯形法求出了等效电路中的元件参数值,计算了电极反应速度常数K_s。从分析SnO_2电极修饰不同层的硬脂酸二茂铁酯L-B膜的界面阻抗和电极反应的动力学性能,表明与在固相中研究的硬脂酸二茂铁酯L-B膜的阻抗性能明显不同,在Fe(CN)_6~(3-/4-)溶液中表现了电活性分子修饰电极的界面阻抗行为,进一步证实了修饰在SnO_2电极上的硬脂酸二茂铁酯L-B膜在Fe(CN)_6~(3-/4-)的氧化还原电极反应过程中,起电荷传递的中介作用。     

顺序化学沉积法制备PB/MWNTs复合修饰电极及电化学性能研究

利用Fe3+和[Fe(CN)6]4-溶液,采用顺序化学沉积法制得普鲁士蓝/多壁碳纳米管(PB/MWNTs)修饰电极.FTIR、SEM等结构表征表明普鲁士蓝(PB)直接沉积在多壁碳纳米管(MWNTs)的表面.电化学研究表明PB/MWNTs修饰电极上的电子传递过程受支持电解液中K+、H+浓度影响.在pH=5.6、K+浓度为0.2 mol/L的KOH-KH2PO4-KCl支持电解液中,电极表现出优异的电化学稳定性,且可用于定量测定H2O2浓度.     

负载亚铁氰化钴钾废弃皮革吸附剂对Rb(Ⅰ)的吸附

将亚铁氰化钴钾负载于经碱水解后的废弃皮革上,制备了一种铷离子吸附剂(KCoFC-AWL)。采用SEM、FTIR、XPS和XRD等对其进行了表征。考察了Co(NO_3)_2·6H_2O和K4Fe(CN)_6·3H_2O的质量比、溶液pH、铷离子(Rb~+)初始质量浓度、吸附剂用量和接触时间对吸附效果的影响。结果表明:m[Co(NO_3)_2·6H_2O]∶m[K_4Fe(CN)_6·3H_2O]=3∶4时,制备的0.09 g吸附剂对pH为7、Rb~+初始质量浓度为20 mg/L的Rb~+溶液的吸附率为93.55%,且于6 h达吸附平衡。探究发现,Langmuir等温吸附模型和准二级动力学模型能更好地描述Rb~+在吸附剂上的吸附行为。以1.5 mol/L KCl作为脱附剂,脱附率达90%以上。将该吸附剂用于提取盐湖卤水中的Rb~+,当pH=7时,吸附率为51.19%,该吸附剂具有潜在的实用价值。     

KAu(CN)_2的制备

KAu(CN)_2主要用于电镀金和化学镀金。制备KAu(CN)_2有几种方法,第一是:将小块金在王水中加热溶解,加热除去二氧化氮,使成HAuCl_4,再加NaHSO_3、KOH、KCN制备KAu(CN)_2,或者在HAuCl_4中加KOH中和到pH6,加K_2CO_3中和到pH 7.5～8使之成为KAuCl_4。然后加一定量的KCN溶液,加热使反应完全。趁热过滤,用冰水冷却滤液,即有KAu(CN)_2出现。冷却、结晶完全后离心分离,以水洗涤两次,洗去混在KAu(CN)_2中的KCl,干燥后即为成品。     

EDTA化学镀铜溶液中CuSO4的快速分析

本文确定了分析EDTA化学镀铜溶液中硫酸铜的吸光光度法.醋酸-醋酸钠缓冲溶液中,EDTA-Cu(Ⅱ)具有稳定的阳光度,其含量与吸光度的关系符合比尔定律.镀液中Fe1g/L.K_4Fe(CN)_6·2H_2O10g/L及其它组分对本法测定无干扰.     

基于MIL-53(Fe)的微生物传感器在抗生素检测中的应用

通过将大肠杆菌(E.coli)、海藻酸钠(SA)和MIL-53(Fe)掺杂到聚乙烯醇(PVA)胶体中形成纳米复合材料,并与硼酸交联得到MIL-53(Fe)/E.coli/SA/PVA颗粒。以E.coli作为受试体,K_3[Fe(CN)_6]为媒介体负责转运固定化微生物呼吸作用产生的电子至电极表面,通过监测还原产物([Fe(CN)_6]~(4-))的量的变化,从而得到微生物活性变化的信息,进而衡量药物的有效性。通过筛选MIL-53(Fe)/E.coli/SA/PVA颗粒的最佳形成条件,制备了灵敏的生物探针,搭建了基于固定化微生物的传感体系,并应用于不同抗生素类药物的检测。     

An SECM observation of dissolution distribution of ferrous or ferric ion from a polycrystalline iron electrode

The dissolution of iron as ferrous or ferric ion from a polycrystalline iron electrode during anodic polarization in pH 2.3 sulfate solution was evaluated by using scanning electrochemical microscopy (SECM). A graphite reinforcement carbon (GRC) microelectrode was employed as a probe electrode of SECM to detect ferrous or ferric ions dissolved from the iron electrode in the active-dissolution, passive or trans-passive region. The probe current above the iron electrode surface subjected to active-dissolution showed the dissolution distribution of ferrous ion, depending on the substrate grains. It was found that the active-dissolution rate of iron as ferrous ions from the grain on which the thicker film was formed in the passive region, was lower than that from the grain on which the thinner film was formed in the passive region.     

The electrocrystallisation of cadmium sulphide films of cadmium

The growth of anodic CdS films on polycrystalline Cd takes place in two stages. Initially a barrier film grows to a thickness of about 5nm by high-field ion migration. This film contains as many as 10²⁵ donors in m^?3. When an electrode potential exceeds a critical value, the second stage of film growth begins, and a porous or polycrystalline. CdS layer forms over the original barrier layer. This type of film can thicken to 500 nm or more by a diffusion-controlled process. The kinetics and mechanism of both kinds of film growth are discussed.     

Electrochemical response of a composite Pt/TiO2 layer formed potentiodynamically on titanium surfaces

By potentiodynamic polarization of mechanically polished titanium in a diluted aqueous solution of hexachloroplatinic acid, nearly spherical Pt microparticles were grown, embedded into the simultaneously formed TiO₂ film. The real surface of platinum may be easily controlled by the number of potentiodynamic cycles, and roughness factors exceeding 100 were obtained. Within the potential region of both hydrogen and oxygen underpotential deposition, in both acidic and alkaline solutions, the electrode displayed an excellent electrochemical response characteristic of smooth polycrystalline platinum, unlike to highly dispersed platinum electrodes produced by other methods. The preparation method applied in this work presents an easy way to obtain an electrode surface combining the behaviour of smooth polycrystalline platinum with the behaviour of microdisc arrays. Its high electrocatalytic effectiveness was demonstrated for oxygen reduction and bromide ion adsorption/oxidation.     

柔性染料敏化太阳能电池材料制备工艺参数的优化

采用水热法制备TiO2纳米浆,与P25粒子和TiO2散射大粒子混合制成级配浆料。将所得的浆料涂敷在铟掺杂氧化锡-聚苯二甲酸乙二醇酯导电聚合物基板上,并在120～150℃进行热处理制成光阳极薄膜。利用溅射法制备Pt对电极,将其组装成柔性的染料敏化太阳能电池(dye-sensitized solar cell,DSC)。研究了对电极溅射时间、TiO2薄膜热处理温度、膜厚以及级配浆料中的酸添加量对电池光电性能的影响。结果表明:当对电极Pt溅射时间为30s,TiO2薄膜热处理温度为150℃,膜厚为10.5μm,浆料添加0.05mol/LHNO3时,柔性DSC的光电性能最好,光电转换效率可达4.05%。     

Synthesis and electrochemical study of Pt-based nanoporous materials

In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells.     

Electrocatalytic activity under oscillatory regime: The electro-oxidation of formic acid on ordered Pt3Sn intermetallic phase

Despite the considerable progress in the understanding of the mechanistic aspects of the oscillatory electro-oxidation of C1 molecules, there are apparently no systematic studies concerning the impact of surface modifiers on the oscillation dynamics. Herein we communicate on the oscillatory electro-oxidation of formic acid on ordered Pt₃Sn intermetallic phase, and compare the results with those obtained on a polycrystalline platinum electrode. Overall, the obtained results were very reproducible, robust and allowed a detailed analysis on the correlation between the catalytic activity and the oscillation dynamics. The presence of Sn in the intermetallic electrode promotes drastic effects on the oscillatory dynamics. The decrease in the mean electrode potential and in the oscillation frequency, as well as the pronounced increase in the number oscillations (and also in the oscillation time), was discussed in connection with the substantial catalytic enhancement of the Pt₃Sn towards the electro-oxidation of formic acid. The self-organized potential oscillations were used to probe the electrocatalytic activity of the Pt₃Sn electrode and compare it with that for polycrystalline Pt. The presence of Sn resulted in a significant decrease (2–11 times, depending on the applied current) of the rate of surface poisoning.     

电极极性影响EHD强化沸腾传热的机理

The effects of electrode polarities on EHD enhancement boiling heat transfer were investigated theoretically and experimentally based on the analysis of electric field distribution affected by superheat boundary layer and charge injection. The results showed that electric field distribution was changed by the charge induced by temperature gradients in the superheat boundary layer, but the change was independent of electrode polarities. However, when electric charge injection occurred, the electrode applied positive high voltage might generate different characteristics of charge injection from that generated by applied negative high voltage. If the electric field on the surface of heat transfer increased due to charge injection, the augmentation effects would increase. The experiments demonstrated that positive high voltage gave larger enhancement factors than negative high voltage. The experimental phenomena could be interpreted well on the basis of charge injection characteristics.     

Influence of the grain size of samaria-doped ceria cathodic interlayer for enhanced surface oxygen kinetics of low-temperature solid oxide fuel cell

The catalytic role and grain boundary effect of samaria-doped ceria (SDC) interlayers were investigated. To see the catalytic role, an SDC interlayer was deposited on a single crystalline YSZ (100) substrate by using the pulsed laser deposition (PLD) for an epitaxial film. The grain boundary effects were analyzed with SDC interlayers with various grain sizes on polycrystalline YSZ substrates. As a result, the membrane electrode assembly (MEA) with an epitaxial SDC interlayer exhibited a peak power density that was twice that of a YSZ controlled MEA. More detailed experiments were conducted with MEAs with various grain sizes. In the electrochemical analysis, the MEA with a nano grain SDC interlayer showed an increased maximum power density and lower cathodic impedance. This result suggests that the performance of low temperature solid oxide fuel cells (LT-SOFCs) could be enhanced by applying an SDC interlayer with nano grains for the enhanced oxygen reduction reaction.     

固体电解质膜对PEMFC电极动力学的影响

研究了不同种类的固体电解质膜对质子交换膜燃料电池性能的影响,采用相同组成的气体扩散电极与制作工艺,分别用Nafion 111、Nafion 112、Nafion 1135、Nafion 115、Dow 800固体电解质膜制成MEA,并组装成单电池,用极化曲线法与交流阻抗法研究了单电池的极化行为与电气特性,并用zsimwin软件模拟了电气特性参数。结果表明,随着固体电解质膜变薄,电池内阻变小,但电池开路电压却反而降低,固体电解质膜的厚度较大(如Nafion 115)或较小(如Nafion 111)都会使电极双电层微分电容变小,使电极电化学反应动力学变差,离子交换容量大的电解质膜电导率大,电极电荷传递阻力较小,反应阻抗小。