羟基新戊醛在PbO2-SPE组合电极上的电氧化研究

采用热压-电镀法制得PbO₂-固体高聚物电解质(SPE)组合电极. 通过伏安曲线和槽压与过电位曲线的测量, 研究羟基新戊醛在该组合电极上电氧化行为. 通过PbO₂-SPE组合电极在阳极液中有、 无液相支持电解质及不同阴极液情况下的循环伏安曲线和线性伏安曲线比较, 证明该组合电极对羟基新戊醛氧化有较好的电催化作用.     

不同电极材料和不同酸介质对3-甲基吡啶电氧化的影响

在以质子交换膜为隔膜的电解池内,通过3-甲基吡啶在PbO₂/Ti、SnO₂/Ti、石墨和MnO₂/Ti电极上的电氧化研究发现,在硫酸溶液中,PbO₂电极是催化活性最高的工作电极.通过3-甲基吡啶在硫酸、高氯酸、磷酸和乙酸介质中的电氧化研究发现,对于PbO₂电极,硫酸是最适合的介质.利用循环伏安实验和恒电位电解实验,研究了电氧化条件和电催化活性,比较了各种条件下的电流效率和选择性.     

2-甲基吡啶在PbO2-SPE组合电极上的电氧化研究

分别采用热压法和热压-电镀法制备PbO2-SPE组合电极, 通过循环伏安和稳态极化曲线测量, 研究了这两种电极对2-甲基吡啶电氧化反应的电催化活性, 同时考察了工作电极电解液中有、无液相支持电解质电位与电流密度的关系及不同对电极电解液情况下, 电流密度与过电位和过电位与槽压的关系. 通过一般PbO2电极与热压-电镀法PbO2-SPE组合电极在电流密度与过电位和电流密度与槽压变化的比较, 发现热压-电镀法制备的PbO2-SPE组合电极在相同过电位下具有更高的电流密度, 在相同电流密度下具有较低的槽压.     

3-甲基吡啶电氧化合成烟酸的研究

在有阳离子交换膜的电解槽内,通过稳态极化曲线测量,考察了3-甲基吡啶在Pt电极和PbO₂/Ti电极上的电极反应,发现PbO₂/Ti电极对生成烟酸有电催化作用.通过高效液相色谱分析,进一步考察了各种因素对电流效率的影响.     

表面活性剂对3-甲基吡啶电氧化制取烟酸的影响

研究了在阳极液中加入不同类型和不同浓度表面活性剂对3-甲基吡啶电氧化的影响. 结果表明, 十六烷基三甲基溴化铵、脂肪醇聚氧乙烯醚硫酸钠、十二烷基苯磺酸钠、十二烷基二甲基甜菜碱和山梨醇酐单硬脂酸酯的胶团对3-甲基吡啶电氧化有明显的促进作用. 实验结果还表明, 在低浓度的硫酸为支持电解质阳极液中加入表面活性剂与不加表面活性剂相比, 3-甲基吡啶电氧化制取烟酸的选择性和电流效率明显提高.     

丙酮-水混合溶剂中3-甲基吡啶的电氧化

在以质子交换膜为隔膜的电解槽内, 通过3-甲基吡啶在PbO2电极上的电氧化研究, 发现在丙酮-水混合溶剂中, 与纯水作溶剂相比, 不仅在相同阳极电位下电流密度大幅度上升, 3-甲基吡啶电氧化生成烟酸的选择性和电流效率也明显提高. 通过循环伏安、极化曲线和恒电位电解实验, 研究了在丙酮-水混合溶剂中3-甲基吡啶的电氧化条件, 并比较了不同条件下的选择性和电流效率.     

钕掺杂二氧化铅复合阳极的电化学性能研究

利用电沉积法制备了钕（Nd）掺杂钛（Ti）基二氧化铅（PbO₂）复合阳极,采用扫描电子显微镜（SEM）、X 射线衍射（XRD）、电化学阻抗谱、线性扫描伏安法、循环伏安法等对所制备电极的表面形貌、物相组成及电化学性能进行了分析. 结果表明,Nd 掺杂使得 PbO₂ 阳极表面颗粒变小、结构更加致密,增大了电极比表面积,改善了电极电化学性能. PbO₂ 和 PbO₂-Nd 阳极表层主要为β- PbO₂,Nd 掺杂提高了β- PbO₂ 的结晶纯度,改变了表面相的相对丰度,促进了β(101)晶面形成. PbO₂-Nd 阳极具有更小的电化学反应电阻,更高的析氧电位,更强的电子交换能力和更长的使用寿命. 将所制备电极应用于处理苯酚模拟难降解有机废水,PbO₂-Nd 阳极对苯酚具有更好的电催化氧化效果,降解3 h,苯酚去除率达85.7%,COD 去除率达73.8%. 循环使用6 次,PbO₂-Nd 阳极电催化活性无明显衰减,显示出更好的电催化耐久性.     

2-甲基吡啶在不同有机物/水混合溶剂中的电氧化研究

通过循环伏安、线性扫描伏安测量和恒电位电解实验, 在以质子交换膜为隔膜的电解槽内, 分别以丙酮、乙腈和2-丁酮3种有机物与水作混合溶剂, 研究了2-甲基吡啶在PbO2电极上的电氧化行为. 与纯水溶剂比较发现, 在丙酮与水混合溶剂中, 2-甲基吡啶电氧化生成2-吡啶甲酸的选择性和电流效率最高, 阳极氧化电流密度也明显提高, 完全可以替代在纯水溶液中进行2-甲基吡啶电氧化反应.     

ZrO2掺杂铌基二氧化铅电极制备及其甲基橙降解电催化性能

本文利用电沉积制得ZrO₂掺杂铌基二氧化铅电极,通过扫描电镜（SEM）和X射线衍射（XRD）观察表征了Nb/ZrO₂+PbO₂电极表面形貌特征及组成. 用线性伏安曲线、电化学交流阻抗和循环伏安曲线测试了Nb/ZrO₂+PbO₂电极电化学性能,及其甲基橙（MO）的降解电催化效果. 结果表明,ZrO₂掺杂使Nb/PbO₂电极表面更致密、粗糙,结晶尺寸更小,增大了电极比表面积,提高了电极电催化活性. Nb/ZrO₂+PbO₂电极活性层主要由β-PbO₂和少量的α-PbO₂以及部分ZrO₂共沉积而成. 有较高的析氧电位、吸附电容和较低的电荷转移电阻,其甲基橙（MO）降解电催化活性更佳,降解过程受扩散控制.     

Nd-Fe-MoO42-氰桥混配聚合物修饰铂电极的丙三醇电催化氧化

利用软模板结合电沉积法制备了一种有序化氰桥混配聚合物修饰铂电极（Nd-Fe-MoO₄^2-/Pt）,用循环伏安法研究了在该化学修饰铂电极的丙三醇电催化氧化,并重点讨论了支持电解质的H⁺和SO₄^2-浓度、丙三醇浓度、扫速等因素对丙三醇电催化氧化活性的影响. 结果表明,在弱酸性硫酸钠支持电解质中,适当量SO₄^2-的存在有助于提高Nd-Fe-MoO₄^2-/Pt电极的丙三醇电催化氧化电流;-0.2 ~ 0.3 V电位区间内,其丙三醇氧化峰电流1与循环伏安曲线扫描速率的平方根之间呈现良好的线性关系,体现了扩散控制的反应特性;Nd-Fe-MoO₄^2-/Pt电极的丙三醇电催化氧化电流密度值约为裸铂电极的4倍,而丙三醇电催化氧化反应的表观活化能相对较小,修饰电极的电催化氧化呈现了明显的协同效应,其电催化氧化活性高、电流响应快、催化稳定性好.     

Electrocatalysis and determination of hydrazine compounds in liquid chromatography at a mixed-valent cobalt oxide/cyanocobaltate film electrode

A glassy carbon electrode coated with an electrodeposited film of mixed-valent cobalt oxide/cyanocobaltate (CoO/CNCo) enabled hydrazine compounds to be catalytically oxidized at the greatly reduced overpotential and in a wide operational pH range (pH 2.0-7.0). Electrocatalytic activity at the CoO/CNCo modified electrode was evaluated with respect to solution pH, film thickness, supporting electrolyte ions, potential scan rate, operating potential, concentration dependence and other variables. The CoO/CNCo film electrode was completely compatible with a conventional reversed-phase liquid chromatographic (RP-LC) system. Practical RP-LC amperometric detection (RP-LCEC) of hydrazines was performed. A dynamic linear response range over three orders of magnitude and a detection limit at the pmol level were readily obtained. The CoO/CNCO film electrode exhibited excellent electrocatalytic stability in the flowing streams.     

Amperometric detection at a carbon-fibre array ring/glassy-carbon disk electrode in a wall-jet cell

A wall-jet cell incorporating a carbon fibre array ring/glassy-carbon disk electrode has been constructed, and characterized by the cyclic voltammetry and flow-injection techniques. The ring (composed of several microdisks) and glassy-carbon disk electrode, can be used separately for different purposes, e.g., detection in solution without a supporting electrolyte, collection/shielding detection with dual-electrode and voltammetric/amperometric detection with series dual-electrode. The electrode shows better collection and shielding effects than the usual ring-disk electrode in quiescent solution and the series dual-electrode in a thin-layer flow-through cell. The detection limit at the ring electrode is comparable with that at a conventional-size electrode, and has been used in the mobile phase without a supporting electrolyte, proving to be a promising detector for normal-phase liquid chromatography.     

Effects of tetrabutylammonium hydrogen sulfate as an electrolyte additive on the electrochemical behavior of lead acid battery

Tetrabutyl ammonium hydrogen sulfate is an ion-paring reagent that has similar properties with ionic liquid. Ionic liquids belong to new branch of salts with unique properties that have ever increasing applications in electrochemical systems especially lithium-ion batteries. For the first time, the effects of tetrabutylammonium hydrogen sulfate (TBAHS) as an electrolyte additive in battery’s electrolyte was studied on the hydrogen and oxygen evolution overpotential and anodic layer formation on lead–antimony–tin grid alloy of lead acid battery by using cyclic voltammetry and linear sweep voltammetry in aqueous sulfuric acid solution. The grid surface morphology after cyclic redox reaction was studied by using scanning electron microscopy. The results show that, by increasing TBAHS concentration in the electrolyte, hydrogen and oxygen overpotential were increased, and so the crystalline structure of PbSO₄ layer changed. Also, cyclic voltammogram on carbon–PbO paste electrode shows that with presence of TBAHS in the electrolyte, oxidation and reduction peak current intensively increased and peak potential for oxidation and reduction of PbO were dependent on TBAHS concentration.     

Electrochemical behavior of mesoionic sydnone derivatives at wax-impregnated carbon paste electrode

The-N=N-moiety in the mesoionic 3-phenyl sydnone and its derivatives like tolyl sydnones and anisyl sydnones undergo two-electron irreversible electrochemical reduction in Britton-Robinson (BR) buffer at wax-impregnated carbon paste electrodes. Infrared, nuclear magnetic resonance, and mass-spectral data, used to characterize the reduced product, confirm the proposed mechanism. The pasting liquid at the surface of the electrode is found to decrease the electron-transfer rate and cause a higher overpotential compared to homogeneous electrodes. The influence of variation of pH on the peak current and peak potentials is studied in the acidic range. The cathodic peak shifts to more negative potentials with increase in pH, indicating the involvement of proton in the reduction process. This could be a new method of preparation of 2,4-dihydro-3-substituted 1,2,3-oxadiazole-5-one. The substituent effect and the effect of variation of scan rate, concentration, and temperature on peak currents and peak potentials is discussed. The cathodic shift in various organic co-solvents (methanol, acetonitrile, DMF, DMSO) using BRB as the supporting electrolyte is examined. Published in Russian in Elektrokhimiya, 2006, Vol. 42; No. 7, pp. 862–868. The text was submitted by the authors in English.     

Effect Factors in Synthesis of Nicotinic Acid by Electrooxidation of 3-Picoline

IntroductionNicotinic acid,whose IUPAC name is3-pyridineformic acid,also called Vitamin B3,is an importantraw material of chemical industry,an intermediate inthe synthesis processes of medicine,additives of food,drink and feed.It is also applied to anti-oxidants in ac-tive dyestuff and household chemicals,such as hair dyeand hair tonic agents,plastic stabilizer and photo-sen-sitive materials,etc.[1—3].There are a fewmethods forsynthesizing nicotinic acid at present.The oxidation of3-picoli…     

Ta/BDD薄膜电极电化学催化氧化硝基酚

研究了热丝化学气相沉积法(HFCVD)制备得到钽衬底掺硼金刚石膜电极(Ta/BDD)的物理性质和电势窗口, 并考察了其用于电化学催化氧化硝基酚过程中的性能及各种影响因素. 扫描电镜和拉曼光谱表明, Ta/BDD电极具有良好的物理性能, 通过测试Ta/BDD电势窗口发现, 该电极具有较高的析氧过电位. 在Ta/BDD电化学催化氧化硝基酚过程中, 化学需氧量(COD)和高效液相色谱测试表明, 硝基酚能够有效降解, 电流密度、支持电解液及浓度对降解过程影响较大, 温度影响不明显. 强化寿命实验表明, Ta/BDD电极具有较好的稳定性. 实验结果表明, Ta/BDD电极是一种适于硝基酚降解和COD去除的优良电极.     

Mechanically immobilized nickel aquapentacyanoferrate modified electrode as an amperometric sensor for the determination of BHA

Nickel aquapentacyanoferrate (NAPCF), a novel transition metal complex has been prepared and its ability to act as an electrocatalyst for BHA oxidation has been demonstrated. The cyclic voltammetric behaviour of the NAPCF modified electrode prepared by mechanical immobilization on the graphite electrode was well defined. A pair of redox peaks corresponding to the electrochemical behaviour of the NAPCF was observed at 0.35 V and 0.31 V, corresponding to the anodic and cathodic peaks respectively, with a formal potential of 0.33 V. The NAPCF modified electrode favoured electrocatalytic oxidation of BHA to occur at a greatly minimized overpotential of 0.48 V. Experiments were performed to characterize the electrode as an amperometric sensor for the determination of BHA. The anodic peak current was linearly related to BHA concentration in the range of 6.24x10(-7) M to 2.19x10(-4) M with a detection limit of 2.49x10(-7) M and a correlation coefficient of 0.9979. Amperometry in stirred solution exhibited quick and sensitive response to BHA, showing the possible application of the modified electrode in flow system analysis. The modified electrode retained its initial response for more than 2 months when stored in supporting electrolyte, owing to the chemical and mechanical stability of the NAPCF mediator. This modified electrode was also quite effective in the determination of BHA in commercial samples.