锰取代Keggin型杂多酸[ZnW11O39Mn(H2O)]8-在化学修饰玻碳电极上的多层组装及电催化性能研究

在4-氨基苯甲酸修饰的玻碳电极上制备了过渡金属取代杂多酸[ZnW₁₁O₃₉Mn(H₂O)]^8-(ZnW₁₁Mn)多层膜.各层的循环伏安行为证明膜的增长均匀,峰电流随层数的增加而增加.与其在溶液中的氧化还原行为相比,多层膜中的ZnW₁₁Mn显示出一些特殊的性质.还讨论了pH对其氧化还原行为的影响.该多层膜对BrO₃^-和H₂O₂的还原及抗坏血酸的氧化具有较好的电催化性能.     

磷钼钒类杂多酸—聚吡咯薄膜修饰电极及其电催化性能研究

合成了磷钼类杂多酸，采用电化学方法首次在导电基体玻碳电极上研制了磷钼钒类杂多酸－聚吡咯薄膜修饰电极，该电极性能稳定，经久耐用，对膜修饰电极的电化学行为进行了表征，研究了膜修饰电极酸性水溶液中的氯酸根、溴酸根，、磺酸根，亚硝酸根，三阶铁离子，     

Keggin型钼钒磷杂多酸催化剂上丙烷选择氧化性能的研究

系统研究了不同数目V⁵⁺取代的钼钒磷杂多酸H_3+nPMo_12－nV_nO₄₀ (n＝0～4)催化剂上丙烷选择氧化反应性能. 通过BET, IR, TPR, 紫外-可见光谱等表征手段对催化剂的理化性质进行了考察, 并对催化剂的结构-性能关系进行了初步关联. 在杂多酸的一级结构中, V⁵⁺对Mo⁶⁺的取代不仅改变了杂多阴离子金属-氧桥的键强以及晶格氧的插入能力, 而且也相应地调变了样品的酸量. 催化剂活性随V⁵⁺取代数量的递增而增强; 适宜数量的V⁵⁺取代提高了含氧酸产物的选择性, 而过量的V⁵⁺取代则导致部分氧化产物的深度氧化. 考察了在Keggin型杂多酸二级结构上引入钒物种的影响, 也即将钒物种(VO)²⁺作为抗衡离子取代部分质子以调变催化剂的结构与性质. 实验表明, 处于一级结构和二级结构[(VO)²⁺抗衡离子]中的V在反应中均可离析出少量V₂O₅物种. 适宜量的(VO)²⁺物种以及离析出来的少量V₂O₅物种可能均对催化剂的性能有贡献. 显然, 钒在不同位置的价态变化以及形态的不同, 会导致催化性能的相应改变.     

SiW_(12)O_(40)~(4-)在玻碳电极上的多层组装及电催化性能研究

本文采用层层自组装法制备包含杂多酸SiW_(12)O_(40)~(4-)(SiW_(12))和聚合物阳离子聚二烯丙基二甲基氯化铵(PDDA)的多层膜修饰电极,并用循环伏安法研究其对BrO_3~-和NO_2~-体系还原的电催化性能.结果表明:SiW_(12)修饰电极对BrO_3~-和N_2O~-的还原具有明显的电催化作用.催化电流随修饰层数的增加而明显增加.     

钼钒砷三元杂多酸氧化还原性能研究

杂多酸应用十分广泛 ,作为催化剂是迄今为止的一项最广泛、最重要、最具前途的应用。已经用杂多化合物作为催化剂实现工业化的大型项目有八个[1] ,创造了良好的经济效益和社会效益。杂多酸具有酸性和氧化性 ,作为酸型、氧化型或双功能催化剂 ,应用于许多均相和多相催化反应中。其中 ,具有 Keggin结构的杂多酸显示出良好的催化活性 ,是被广泛应用的酸种之一。杂多酸组成元素众多 ,可以通过调变元素的组成和比例来调变其氧化还原性 ,以适应各种不同的催化需要 ,这对于开发新型催化剂具有重要意义。本文合成了四种钼钒砷三元杂多酸 ,经表征确…     

镧取代Dawson型磷钨杂多酸聚吡咯修饰电极的制备及其电化学性能

通过缺位填充法合成了分子式为α２－Ｋ７Ｐ２Ｗ１７Ｏ６１（Ｌａ· ＯＨ２）的镧（Ⅲ）取代十八钨磷酸盐。在玻碳电极（ＧＣ）上,用电化学方法将单取代Ｄａｗｓｏｎ型杂多酸盐α２－Ｋ７Ｐ２Ｗ１７Ｏ６１（Ｌａ·ＯＨ２）的阴离子（Ｐ２Ｗ１７Ｌａ）掺杂到聚吡咯（ＰＰＹ）薄膜中制成Ｐ２Ｗ１７Ｌａ／ＰＰＹ／ＧＣ化学修饰电极,既保持该杂多酸的电化学活性和电催化性能,又具有良好的稳定性和灵敏度。研究表明, ０． ５０ ｍｏｌ／Ｌ ＨＣＩ溶液中,聚吡咯薄膜中 Ｐ２Ｗ１７Ｌａ的第一对氧化还原峰对 ＮＯ２的电还原具有良好的催化活性,其催化电流与 ＮＯ２浓度在 ６．０ × １０－５－ １．０ × １０－２ｍｏｌ／Ｌ范围内呈线性关系。     

Keggin型P-Mo-V杂多酸的合成

杂多化合物(Ｈｅｔｅｒｏｐｏｌｙｃｏｍｐｏｕｎｄ,简写为ＨＰＣ)的结构、性质特殊:化学计量的ＨＰＣ组成简单、结构确定,既有配合物和金属氧化物的结构特征,又有酸性和氧化还原性质,多数在水和含氧有机溶剂中溶解度甚大,而且相当稳定,固态ＨＰＣ的热稳定性也较好,广泛用于催化领域,在医学领域特别是抗癌及抗病毒领域也有较好的应用前景[1]。具有Ｋｅｇｇｉｎ结构的ＨＰＣ具有三级结构,其一级结构为杂多阴离子(Ｈｅｔｅｒｏｐｏｌｙａｎｉｏｎ,简写成ＨＰＡＮ),表达通式为[ＸＭ12Ｏ40]ｎ-8(ｎ为元素Ｘ的氧化数),结构描述以[ＸＯ4]四面…     

磷钼钒杂多酸/聚酰胺-胺复合膜修饰电极的制备及电催化性能

通过静电层层自组装方法在预修饰聚二烯丙基二甲基氯化铵的电极基片上制备了Dawson型磷钼钒杂多酸/聚酰胺-胺多层复合膜. 用X射线光电子能谱、紫外-可见光谱、循环伏安法和原子力显微镜分析表征了多层复合膜的形成过程; 用循环伏安法表征了该复合膜修饰电极的电化学性能, 研究结果表明, 该复合膜修饰的电极稳定性好, 对亚硝酸盐、溴酸盐的还原以及抗坏血酸的氧化具有良好的催化活性.     

N-取代氨乙基膦酸为配位中心的Keggin型杂多酸

用N-取代的β--氨乙基膦酸R₂R′N+CH₂CH₂PO₃H-(R=R′=H;R=Me,R′=H;R=R′=Me; R=H,R′=Me₂CH;R=H,R′=CH₃(CH₂)₂CH₂)为配位中心合成了系列P︰W比为1︰12的有机膦-钨杂多酸,用元素分析、红外、紫外光谱、TG和DSC热分析对其进行了结构表征.结果表明,这些有机膦杂多酸具有Keggin型结构,可表示为N⁺CH₂CH₂PO₃HZ^-·W1₁₂O₃₆·nH₂O.其中铵离子有机侧链R₂R′N⁺CH₂CH₂与膦酸根PO₃H^-一起参与构成杂多阴离子的一级结构,即整个有机膦酸一体作为了杂多阴离子的核心或配位中心.有机膦酸的取代基对杂多酸的结晶水量有显著影响.     

磷钼杂多酸-L-半胱氨酸自组装超分子膜电极对亚硝酸根电催化还原的研究

制备了磷钼杂多酸－Ｌ－半胱氨酸自组装超分子膜电极（Ｐ２Ｍｏ１８－Ｌ－Ｃｙｓ／Ａｕ）。采用水平衰减全反射（ＡＴＲ－ＦＴＩＲ）光谱表征了膜的组成。研究了该膜电极的电化学性质，发现它在１．０ ｍｏｌ／Ｌ　Ｈ２ＳＯ４溶液中，于０．０～０．７Ｖ（ｖｓ．ＳＣＥ）间ＣＶ扫描出现两对稳定、可逆的氧化还原峰，其中峰电位分别为Ｅｍ１＝０．３３４ Ｖ，Ｅｍ２＝０．１８８Ｖ，对应着Ｐ２Ｍｏ１８Ｏ_(６２)~(６－)的两步２电子－２质子反应；计时库仑法计算了薄膜内的电子传递系数Ｄ为５．０１ × １０~（－８）ｃｍ２·ｓ～（－１）。该膜电极对酸性溶液中的ＮＯ_２~－有明显的电催化还原作用，初步探讨了电催化机理。用差分脉冲伏安法（ＤＰＶ）测定其还原峰电流与ＮＯ_２~－的浓度在２．０ ×１０~（－６）～２．０ × １０~（－４）ｍｏｌ／Ｌ范围内呈良好的线性关系，相关系数为０．９９５３，检测限５．０×１０~（－７）ｍｏｌ／Ｌ。该电极用于模拟水样中ＮＯ_２~－的测定，结果满意。     

Multilayer Assemblies Consisting of Tri‐Vanadium‐Substituted Heteropolyanions and Its Electrocatalytic Properties

We describe the controlled fabrication of ultrathin multilayer films consisting of tri‐vanadium‐ substituted heteropolytungstate anions (denoted as P₂W₁₅V₃) and a cationic polymer of quaternized poly (4‐vinylpyridine) partially complexed with osmium bis(2,2′‐bipyridine) (denoted as QPVP‐Os) on the 4‐aminobenzoic acid (4‐ABA) modified glassy carbon electrode (GCE) surface based on layer‐by‐layer assembly. Cyclic voltammetry and UV‐vis absorption spectrometry have been used to easily monitor the thickness and uniformity of thus‐formed multilayer films. The V‐centered redox reaction of P₂W₁₅V₃ in the multilayer films can effectively catalyze the reduction of BrO and NO . The resulting P₂W₁₅V₃/QPVP‐Os multilayer film modified electrode behaves as a much promising electrochemical sensor because of the low overpotential for the catalytic reduction of BrO and NO , and the catalytic oxidation of ascorbic acid.     

Palladium-Substituted Keggin Type Polyoxotungstate Chemically Modified Electrode and Its Catalytic Activity Toward Hydrogen Peroxide Reduction

Abstract

Keggin type heteropolytungstate, in which one of the positions normally occupied by a tungsten cation is occupied by a palladium cation instead, is used to prepare a chemically modified electrode (CME). The electrochemical and electrocatalytic properties of such a CME are investigated. The electron transfer between the palladium-substituted heteropolytungstate and the glassy carbon electrode is fast. The palladium-substituted heteropolyanion CME, with a surface apparent coverage about 1.94 x 10^?9 mol.cm^?2, is shown to be an excellent catalyst for the electrochemical reduction of hydrogen peroxide, while the perfect and lacunary heteropolyanions show no catalytic activity. The effect of solution pH on the stability of the CME, as well as on the electrocatalytic activity toward H₂O₂, was also investigated. The catalytic current increases linearly with increasing concentration of H₂O₂ up to 150mmol.L^?1, and the detection limit is 4.0 x 10^?6mol.L^?1. Due to its sensitivity and durability, this CME could be used as analytical sensor for detecting H₂O₂ in real samples.     

卟啉-金属氧簇超分子化合物的光谱及电催化氧还原

应用紫外可见吸收光谱研究了meso 四(4 N 苄基吡啶基)卟啉(MTBPyP4＋,M=H2,Zn)阳离子与金属氧簇阴离子(SiW12O4－40)在水溶液中的光谱行为. 光谱演变及Job图表明MTBPyP4＋与SiW12O4－40在水溶液中可形成稳定的1∶1的超分子化合物. 同时本文还考察了化学计量为1∶1的[CoTBPyP][SiW12O40]超分子化合物的电催化分子氧还原行为, 表明该类超分子化合物有望成为一类新的催化氧还原的修饰电极材料.     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11NiO6-39 and SiW11MnO6-39 on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11O39Ni(H2O)6-(SiNiW11) and SiW11O39Mn(H2O)6-(SiMnW11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-3 and NO-2 were comparatively studied.     

单核和双核钌配合物在铟锡氧化物电极上的电化学行为及对双酚A的催化氧化

本文应用循环伏安法和微分脉冲伏安法研究了两种新型单、双核多吡啶钌(Ⅱ)配合物在铟锡氧化物(ITO)电极上的电化学行为及对双酚A(BPA)的催化氧化。研究结果表明,单、双核配合物在ITO电极上均出现两个归属为中心离子和亚胺基的氧化波,双核配合物的峰电流约为单核的2倍,表现为通过桥联配体在两中心离子间的电子转移速度较其与电极间的大。同时,两种配合物对BPA的氧化呈现相近的催化氧化活性。此外,讨论了pH值对单、双核钌配合物电化学行为的影响,比较分析了它们对BPA的催化氧化过程。     

Synthesis and Characterization of Intercluster Compounds Consisting of Various Gold Clusters and Differently Charged Keggin Anions

The crystal structures of five intercluster compounds consisting of gold clusters and Keggin anions have been determined by single‐crystal x‐ray diffraction: [Au₉(PPh₃)₈][PMo₁₂O₄₀] (P4/n, Z = 2, a = 24.0195(13), c = 13.6818(10) Å), [Au₉(PPh₃)₈][HSiMo₁₂O₄₀] (P4/n, Z = 2, a = 24.270(3), c = 13.752(2) Å), [Au₉(PPh₃)₈][H₃CoW₁₂O₄₀] (P4/n, Z = 2, a = 24.4776(16), c = 13.7759(13) Å), [Au₈(PPh₃)₈]₂[SiMo₁₂O₄₀] (Pbca, Z = 4, a = 36.269(4), b = 24.488(3), c = 38.612(4) Å) and (nBu₄N)[Au₉(Ptol₃)₈][SiMo₁₂O₄₀] (Cc, Z = 4, a = 24.832(5), b = 24.955(5), c = 40.096(8) Å, β = 106.744(3)°). In these compounds, the charges of the building blocks were varied. Altering the charge on the Keggin anion in combination with the [Au₉(PPh₃)₈]³⁺ cluster gave rise to isostructural compounds as the charge is compensated by protonation of the polyoxometalate anion. Varying the charge or the ligand type of the gold cluster led to compounds with a completely different packing principle.     

One-step synthesis and stabilization of gold nanoparticles and multilayer film assembly

Au nanoparticles (NPs) were synthesized in the one-pot procedure in water at room temperature with the wheel-shaped V^V-V^IV mixed-valence tungstovanadate [P₈W₄₈O₁₈₄{V₄^VV₂^IVO₁₂(H₂O)₂}₂]³²⁻ (V12) acting as both reducing and stabilizing agents. The V12 stabilized Au NPs (Au@V12 NPs) were characterized by SEM, TEM, DLS, UV-vis spectroscopy, XPS, and XRD analyses and the negatively charged surface of the Au@V12 NPs was proved by the zeta potential analysis. Based on the layer-by-layer assembly (LbL), the Au@V12 NPs-containing multilayer films have been fabricated on ITO-coated glass slide and quartz substrates with poly(ethyleneimine) (PEI). The regular growth of the multilayer films was monitored by UV-vis spectroscopy and cyclic voltammetry, the composition was characterized by XPS. The Au@V12 NPs based composite films showed electrocatalytic activities towards the reduction of dioxygen and the oxidation of methanol. This approach is expected to open the way towards procedures aimed at the one-step fabrication of Au NPs and polyoxometalates (POMs) into the multilayer films.     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11 NiO39^6- and SiW11 MnO39^6- on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11 O39 Ni(H2O)^6- (SiNiW11) and SiW11 O39Mn( H2O)^6-( SiMnW11 ) were first immobilized on a 4-aminothiophenol (4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these muhilayer film electrodes for the reduction of BrO3^- and NO2^- were comparatively studied.