环取代基对金属化聚苯胺衍生物膜修饰电极性能的影响

通过比较聚2，5－二甲氧基苯胺（PDMAn）、聚邻甲基苯胺（POT）和聚间氯苯胺（PmClAn）膜修饰电极的氧化还原电位、沉积在这3种聚合物上的铂微粒的表面形态与晶面取向以及异丙醇在分散Pt微粒的聚苯胺膜修饰电极上的氧化行为，从电子效应和立体效应探讨了聚合物电化学性质与环取代基的关系以及不同聚合基质对Pt沉积机理和有催化性能的影响,结果表明，在硫酸溶液中PDMAn膜修饰电极的氧化还原电位最负、POT次之、PmClAn最正，Pt在PDMAn和POT膜上的电沉积机理与在PmClAn膜上的不同，聚合物膜上沉积的Pt微粒呈现（200)晶面择优取向，其中POT膜上择优取向度最大，PDMAn次之，Pm-ClAn最小，异丙醇在金属化聚合物膜电极上的氧化电位取决于聚苯胺的本质，在POT膜修饰电极上异丙醇的电氧化主要发生在POT的活性电位区，而在PDMAn与PmClAn膜上的电氧化则主要发生在Pt上的氧化电位区，说明聚合物膜不仅作为Pt微粒的分散介质，而且本身有产生催化作用。     

金属化聚邻甲苯胺膜修电极的性能研究

在聚邻甲苯胺（POT）膜修饰电极上用电化学法沉积Pt微粒,由SEM与XRD表征其表面形态与晶面取向,同时研究异丙醇在金属化POT膜电极上的氧化行为。结果表明,Pt在POT膜上的沉积呈现晶面择优取向的现象,况且POT质子掺杂后,由于电化学活性增强,影响了沉积铂微粒的尺寸和粒径分布,异丙醇的电氧化可发生在POT的电化学活性区,当电位大于0．70V（SCE）时,POT不再呈氧化还原活性,异丙醇的电氧化主要在铂微粒上进行,聚合物不仅作为铂微粒的载体而且自身参加反应,这种微异相催化体系需用新的模型描述。     

金属化聚邻甲苯胺膜修饰电极的性能研究

在聚邻甲苯胺 (POT)膜修饰电极上用电化学法沉积Pt微粒 ,由SEM与XRD表征其表面形态与晶面取向 ,同时研究异丙醇在金属化POT膜电极上的氧化行为 .结果表明 ,Pt在POT膜上的沉积呈现晶面择优取向的现象 ,况且POT质子掺杂后 ,由于电化学活性增强 ,影响了沉积铂微粒的尺寸和粒径分布 .异丙醇的电氧化可发生在POT的电化学活性区 ,当电位大于 0 .70V(SCE)时 ,POT不再呈氧化还原活性 ,异丙醇的电氧化主要在铂微粒上进行 .聚合物不仅作为铂微粒的载体而且自身参加反应 ,这种微异相催化体系需用新的模型描述     

铂微粒修饰聚2，5－二甲氧基苯胺电极对甲醇的电催化作用

将以铂微粒修饰玻碳电极（ＧＣ）为基体的聚２，５－二甲氧基苯胺膜（ＰＤＭＡ）形成修饰电极（Ｐｔ／ＰＤＭＡ／ＧＣ）．循环伏安实验表明，Ｐｔ／ＰＤＭＡ／ＧＣ电极对甲醇氧化比分散于玻碳电极上的铂催化活性更大。讨论了ＰＤＭＡ膜厚度、铂微粒含量及甲醇浓度对催化活性的影响。这种电极在酸性甲醇溶液中具有良好的稳定性。     

甲醇在铂微粒修饰的聚硫堇电极上的电催化氧化

利用电化学循环伏安和现场ＦＴＩＲ反射光谱等技术研究了甲醇在铂微粒修饰的聚硫堇电极上的电催化氧化。结果表明，循环伏安法制备的铂微粒均匀分散于聚合物膜上，其粒径大小约为３０－１３０ｎｍ；复合修饰电极对甲醇电化学氧化呈现了较高的催化活性，其催化活性的大小依赖于Ｐｔ载量。现场ＦＴＩＲ光谱实验揭示了线性吸附的ＣＯ物种是甲醇在复合电极上氧化的唯一中间体，这种吸附的ＣＯ物种在复合修饰电极上更容易被氧化为最终产物     

铂/聚邻甲基苯胺/碳材料掺杂碳糊电极对甲醇的催化氧化

以石墨和液体石蜡油为主要原料,分别制备了掺杂不同量多壁碳纳米管(MWCNT)、石墨烯(GRA)、电容活性炭(YEC)和电池活性炭(YBC)的多种碳糊底电极Y-CPE(Y代表各种掺杂碳材料,CPE代表纯碳糊电极).采用恒电位法在-0.10 V(vs.Ag/Ag Cl)电位下将铂电沉积到这些电极上.结果表明,当电池碳的含量为14%时,Pt/YBC-CPE(14%)复合电极对甲醇具有最好的电催化氧化活性.采用恒电位方法在0.85 V(vs.Ag/Ag Cl)电位下将聚邻甲基苯胺(POT)电聚合沉积到纯碳糊电极CPE和含有电池碳的YBC-CPE(14%)电极上,得到复合电极POT/CPE和POT/YBC-CPE(14%),再通过恒电位方法将铂电沉积到这2个复合电极上.扫描电镜(SEM)观察结果表明,在Pt/CPE,Pt/YBC-CPE(14%),Pt/POT(6.5 mC)/CPE和Pt/POT(6.5 mC)/YBC-CPE(14%)4个复合电极中,在Pt/POT/YBC-CPE(14%)复合电极上的铂粒子的尺寸最小,并且Pt/POT(6.5 mC)/YBC-CPE(14%)复合电极电催化氧化甲醇活性最高.在POT(6.5 mC)/CPE和POT(6.5 mC)/YBC-CPE(14%)上Pt纳米颗粒的电沉积过程是一个近似的3D成核过程.研究还发现,复合电极Pt/POT/CPE和Pt/POT/YBC-CPE电催化氧化甲醇的活性随POT膜厚度的增加先增大后减少,存在一个最佳的膜厚度.     

聚苯胺和聚吡咯膜电极对Fe（Ⅱ）和Sb（Ⅲ）电催化作用

Ｆｅ（Ⅱ）和Ｓｂ（Ⅲ）的氧化还原峰电流在聚苯胺（ＰＡｎ）和聚吡啶（ＰＰｙ）膜电极上比在铂丝电极上高出一倍至数倍。在膜电极上氧化峰电位与还原峰电位之差值（△Ｅｐ）也比在铂丝电极上显著减小．说明两种膜电极对Ｆｅ（Ⅱ）和Ｓｂ（Ⅲ）离子的电极反应有较好的电催化活性。在电位扫描速度较低时，两种离子在聚合物膜电极上的氧化和还原反应的催化活性相近。     

Pt微粒修饰纳米纤维聚苯胺电极对甲醇氧化电催化

以脉冲电流法制备的纳米纤维状聚苯胺(PANI)为Pt催化剂载体，用它制备了甲醇阳极氧化的催化电极Pt/（nano-fibular PANI）.研究结果表明, Pt/（nano-fibular PANI）电极对甲醇氧化具有很好的电催化活性,并有协同催化作用.在相同的Pt载量条件下， Pt/（nano-fibular PANI）电极比Pt微粒修饰的颗粒状聚苯胺电极Pt/(granular PANI)具有更好的电催化活性.此外， Pt的电沉积修饰方法同样影响Pt/（nano-fibular PANI）电极对甲醇氧化的催化活性.脉冲电流法沉积Pt形成的复合电极较循环伏安法电沉积得到的Pt复合电极具有更优异的催化活性.     

抗坏血酸在PPy-HEImTfa/Pt电极上的电催化氧化及其机理

以铂为基底电极,在1-乙基咪唑三氟乙酸盐(HEImTfa)离子液体中电化学合成导电聚吡咯(PPy),制得PPy-HEImTfa/Pt电极;采用循环伏安法研究了PPy-HEImTfa/Pt电极对抗坏血酸的电催化氧化性能.结果表明:PPy-HEImTfa/Pt电极对0.1mo·lL-1抗坏血酸具有较高的电催化氧化活性,与相同条件下硫酸溶液中在铂表面修饰的聚吡咯(PPy-H2SO4/Pt)电极和裸铂电极相比,其氧化峰电位分别降低了0.10和0.19V,氧化峰电流分别增加了3.0和3.6mA.同时采用原位傅里叶变换红外(insitu FTIR)光谱技术对抗坏血酸在PPy-HEImTfa/Pt电极上的电氧化机理进行了研究,结果表明:抗坏血酸在PPy-HEImTfa/Pt电极上首先被氧化为脱氢抗坏血酸,在水溶液中脱氢抗坏血酸迅速发生水合作用形成水合脱氢抗坏血酸,它进一步水解并发生内酯开环反应生成2,3-二酮古洛糖酸;在较高电位下,部分抗坏血酸最终被氧化成CO2.     

PmClAn基膜修饰电极的电化学及催化性质研究

聚苯胺作为电极修饰材料 ,已在传感器上显示出广泛的应用前景[1～ 4 ] .异丙醇 ( i- P)氧化[5,6 ] 是个较简单的反应 ,被广泛作为电催化研究的模型反应 .目前 ,i- P电化学氧化的研究集中于 Pt的多晶或单晶电极[7～ 9] ,Gonzales等 [10 ] 报道了 Pt- Sn共沉积的 PAn膜修饰电极上的异丙醇电氧化 ,但对复合材料的微观结构仍欠研究 .本文讨论 Pm Cl An基质性质对 Pt电沉积的影响 ,并探讨了 i- P在沉积 Pt微粒的 Pm Cl An功能膜电极上的氧化情况 .1　实验部分1 .1　电极的制备　聚间氯苯胺 ( Pm Cl An,本征态 ud,HCl掺杂态 d)采用乳液聚…     

功能化聚(2,5-二甲氧基苯胺)膜的电化学和电催化性质研究

聚(2，5-二甲氧基苯胺)含有对称的环取代基，其电化学活性可与PAni相比拟．该聚合物具有三种氧化态，即完全还原态(L)、半氧化态(E)和完全氧化态(P)，在伏安曲线上分别于0．19和0．51V处出现L／E和E／P转变峰．掺杂态聚合物和本征态聚合物的氧化还原分别经历L=EH=P和LH=EH=P路径，其中E／P转变峰电位随pH升高而发生负移．铂化的聚合物电极对异丙醇的氧化具有明显的催化作用，且随着扫描时间延长，氧化电流逐渐提高；聚合物与铂微粒相互作用，改变铂微粒的几何结构和电子性质，使催化体系具有良好的催化活性和抗中毒能力．在pH=4．7的缓冲溶液中，该修饰电极对异丙醇氧化仍具有催化活性．聚合物在空气中存放太久(3年)会发生降解，从而影响其电化学性质．     

聚(2,5-二氧基苯胺)膜修饰电极的电化学及催化性质

二甲氧基苯胺;电沉积;氧化;化学修饰电极;聚(2;5-二氧基苯胺)膜修饰电极的电化学及催化性质     

Pt纳米粒子修饰的多孔硅电极的制备及其电催化性能

通过循环伏安法电沉积使直径约为7 nm的Pt纳米粒子均匀地分散于多孔硅表面, 拟用作微型质子交换膜燃料电池的催化电极. 与刷涂法相比较, 电沉积Pt纳米粒子的多孔硅电极(Pt/Si)呈现出高的Pt利用率和增强的电催化活性. 当Pt载量为0.38 mg•cm−2时, 其电化学活性比表面积高达148 cm2•mg−1, 是刷涂相近质量的纳米Pt/C催化剂的多孔硅电极Pt-C/Si的2倍多；该修饰电极对甲醇氧化也呈现了增强的催化性能和好的稳定性, 在0.5 V(vs SCE)极化1 h后电流密度为4.52 mA•cm−2, 而刷涂了相近Pt量的Pt-C/Si电极的电流密度只有0.36 mA•cm−2.     

Electrocatalytic Oxidation of Methanol at Lower Potentials on Glassy Carbon Electrode Modified by Platinum and Platinum Alloys Incorporated in Poly(o‐Aminophenol) Film

The electrocatalytic oxidation of methanol at a glassy carbon electrode modified by a thin film of poly(o‐aminophenol) (PoAP) containing Pt, Pt‐Ru and Pt‐Sn microparticles has been investigated using cyclic voltammetry as analytical technique and 0.10 M perchloric acid as supporting electrolyte. It has been shown that the presence of PoAP film increases considerably the efficiency of deposited Pt microparticles toward the oxidation of methanol. The catalytic activity of Pt particles is further enhanced when Ru or specially Sn is co‐deposited in the polymer film. The effects of various parameters such as the thickness of polymer film, concentration of methanol, medium temperature as well as the long term stability of modified electrodes have also been investigated.     

Methanol Electrooxidation on Smooth Platinum Modified with Ru：the Influence of Ru Coverage and Potentials on Oxidative Current and Products

Methanol oxidation on smooth Pt electrode modified with differ-ent coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current efficiency of formed CO2 was calcu-lated from faraday current and ion current of m/z = 44. The results show that Ru modified Pt electrode with the coverage of ca. 0.3 has the highest catalytic activity for methanol electroox-idation, i. e. faraday current and the current efficiency of CO2 at the low potentials reach to the maximum. In addition, Ru loses its co-catalytic properties at the high potentials.     

X‐ray photoelectron spectroscopy analysis of the stability of platinized catalytic electrodes in dye‐sensitized solar cells

The stability of platinized catalytic electrodes prepared by thermal decomposition of hexachloroplatinic acid was investigated. The platinum on the electrode did not dissolve in the presence of the electrolyte containing an iodide/triiodide redox couple, even under anodic bias. The electrocatalytic activity of platinized catalytic electrodes sealed in a cell with oxygen‐free electrolyte did not decrease within 23 weeks. However, the charge transfer resistance value of platinized catalytic electrodes increased tenfold when the electrodes were heated at 150° for 15 min in air during the sealing process and doubled when the electrodes were reused. The XPS analysis results showed that part of the platinum catalyst on the surface of the electrode was transformed to Pt[II] and Pt[IV] during the thermal sealing process, which led to the decrease of catalytic activity of the platinized catalytic electrodes for the reduction of triiodide. A large amount of inactive iodine absorbed on the surface of the reused electrode, which was confirmed by XPS, also decreased the electrocatalytic activity of the electrodes. The electrocatalytic activity of reused electrodes can be recovered by heating again at 390 °C or removing the platinum oxide and inactive iodine by the electrochemical method. Copyright © 2004 John Wiley & Sons, Ltd.     

Experimental study of platinized poly-2,5-dimethoxyaniline electrodes

In the domains of chemical catalysis and analytical chemistry, the modification of metal electrodes by the deposition of multilayers was developed about twenty years ago. The purpose of our work was to compare the behavior of an electrode prepared with a substituted polyaniline with that of electrodes regularly used in analytical chemistry: platinum, platinized platinum and glassy carbon. We initially present results obtained with poly-2,5-dimethoxyaniline (PDMAn) on two classic systems: the couple Fe(CN)₆^3–/Fe(CN)₆^4– and the couple O₂/OH^–. The first example is often studied during training in electrochemistry because of the good results generally obtained. Levich’s equation is effectively well verified. On the other hand, reduction of oxygen and oxidation of OH^– ions are always limited by the rate of the electron transfer reactions. It seems to us that the study of the behavior of these two systems with platinum electrodes covered with PDMAn, platinized or not, could be interesting. The oxidation of isopropanol in a weakly acid medium was also investigated. In the field of analytical chemistry, a more detailed study is mandatory before deciding on the possibility of using electrodes modified with films of substituted polyaniline. An electrode, which would not be platinized, does not seem useful; the use of electrodes prepared with platinized polymers deposited on substrates less expensive than platinum, (glassy carbon for example), may be more interesting. It seems that H₂O₂ formation over a wide domain of potential would be the best result for oxidations and new experiments will be investigated.