原位紫外-可见光谱和电化学方法研究苯胺聚合过程中的降解

用电化学及光谱电化学研究了硫酸溶液中苯胺在玻碳电极上的聚合降解过程 ,在 - 0 2～ 1 0V电位范围 ,循环伏安图显示了四对氧化还原峰 .通过比较聚苯胺 (PAn)膜在硫酸空白溶液和含对氨基苯酚 (PAP)的硫酸溶液中的循环伏安曲线及电化学聚合时溶液的紫外 可见吸收光谱 ,证明了PAn膜的降解产物PAP的存在 ,同时原位现场紫外 可见吸收光谱法初步研究了苯胺聚合降解的动力学过程 .     

碳基针孔组合微电极的性能测试与理论验证

在涂敷绝缘漆的碳电极上，用针尖刺穿绝缘膜，形成组合微盘电极.在铁氰化钾与亚铁氰化钾溶液体系测得电极的循环伏安曲线与理论计算曲线十分吻合.阶梯扫描伏安法测得的极限扩散电流，与亚铁氰化钾浓度和扫描速率平方根都成良好的线性关系.在氯化钾支持电解质溶液中，测得Cd(Ⅱ)的循环伏安曲线是不可逆的， Cd(Ⅱ)的还原波峰电位在－0.98 V（相对于饱和甘汞电极）附近； 800 mV•s－1阶梯扫描速率下，在2.55×10－5 ～1.28×10－4 mol•dm－3浓度范围内， Cd(Ⅱ)的浓度与还原波峰电流成良好的线性关系.     

聚苯胺对2,5-二巯基-1,3,4-噻二唑氧化还原反应的电化学催化作用的循环伏安研究

研究了聚苯胺(PAn)膜电极在2,5-二巯基-1,3,4-噻二唑(DMcT)溶液中电化学处理或浸泡后的循环伏安(CV)曲线的变化规律.实验结果表明,PAn膜电极在DMcT溶液中进行电化学处理或浸泡过程可使DMcT进入PAn膜内部与PAn形成复合物.PAn对DMcT的电化学催化作用可能和二者之间形成的电子给体-受体复合物有关.该复合物的电化学氧化还原特性不同于PAn和DMcT,其氧化还原反应速率和可逆性均优于DMcT.     

Pt/PAn/Ti电极的制备及对甲醛的电催化氧化

通过循环伏安的电化学方法在金属钛基体上先后进行苯胺的聚合和金属铂的电化学沉积,得到以金属钛为基体的聚苯胺载铂电极(Pt/PAn/Ti),并通过扫描电镜和循环伏安法对该电极进行了表征。通过研究甲醛在该电极上的电催化氧化行为,考察了载铂量对甲醛氧化效果的影响及PAn在电催化氧化甲醛的过程中所起的作用。结果表明,载铂量与甲醛的氧化有一定的关系,PAn的存在使得铂微粒分散程度更好,有效面积更大,与相同铂沉积量的Pt/Ti电极相比,甲醛在其上的正向扫描氧化峰电流密度增加了2.3倍,电位负移了40mV;反向扫描氧化峰电流密度增加了5倍,电位负移了30mV。同时,PAn的存在也增强了电极的抗中毒能力。     

PANI膜电聚合过程及电控分离苯酚的EQCM研究

通过电沉积方法在镀铂石英晶片上制备了导电聚苯胺(PANI)膜,采用电化学石英晶体微天平(EQCM)技术探讨了苯胺聚合机制及在苯酚溶液中的氧化还原特性.在0.5 mol/L硫酸溶液中结合循环伏安法考察了PANI膜在完全还原态(L)-半氧化态(E)-完全氧化态(P)之间的电活性和稳定性;在不同浓度的苯酚溶液中结合恒电压阶跃...     

纳米TiO2/聚苯胺复合膜电极的制备及其电化学性能

采用1mol·L-1硫酸作为介质,扫描速度为100mV*s-1,扫描电位为-0.2V～0.8V,用循环伏安法在纳米二氧化钛(Nano-TiO2)膜电极上实现了苯胺(Aniline)的电化学聚合,并对制得的Nano-TiO2/聚苯胺复合膜的电化学性质进行了研究.结果表明在峰电位(Ep)为0.28V处有一个明显的氧化峰,在Ep为 0.54V,0.08V,-0.06V处分别有一个还原峰,经长时间扫描,氧化峰电流可达到50mA·cm-2,具有工业应用价值.同时实验也表明,复合膜的生成、Ip的大小受溶液浓度、扫描速度以及扫描电位的影响.     

甲酸在钼青铜修饰铂电极上的催化氧化

应用循环伏安法和双电位阶跃法研究了不同浓度硫酸中钼酸盐在多晶铂电极上的电化学行为 .在硫酸溶液中 ,当电位负向扫描时 ,钼酸盐即于铂电极上还原形成钼青铜 ,吸附在电极表面 ;电位正向扫描时钼青铜将再被氧化 ,氧化机理受硫酸浓度的影响 .铂电极因钼酸盐的还原和钼青铜的氧化而得到修饰 .在硫酸钠溶液中以此修饰的铂电极对甲酸氧化有明显的催化作用 ,其氧化峰电流接近未修饰铂电极上的 2倍 .钼青铜对铂的不完全修饰或过分修饰均会减弱甲酸氧化的催化作用     

双席夫碱铜配合物修饰玻碳电极用于碳酸饮料中苯甲酸的测定

利用溶液法制备双席夫碱铜配合物(M),采用电沉积法将制备的M沉积在玻碳电极(GCE)上制备了双席夫碱铜配合物修饰电极(M/GCE),用于测定碳酸饮料中的苯甲酸的含量。元素分析和红外光谱结果显示,试验成功制备了M;电沉积过程循环伏安曲线变化结果显示M已成功沉积在了GCE表面;扫描电镜(SEM)结果显示M/GCE表面已形成了一层聚合物膜。三电极体系选用M/GCE(工作电极)、饱和甘汞电极(参比电极)、铂丝电极(辅助电极);支持电解质采用0.1mol·L~(-1) KCl溶液;电化学方法选用循环伏安法(CV),扫描速率为50mV·s~(-1)。结果表明,苯甲酸在M/GCE上的氧化峰电位和还原峰电位分别位于-0.007,-0.359V附近,电极反应可逆性良好,受扩散控制。苯甲酸浓度与其对应的氧化峰电流在0.001 0～2.000 0mmol·L~(-1)内呈线性关系,检出限(3S/N)为0.27μmol·L~(-1)。将电极在4℃下放置7d后,苯甲酸氧化峰电流下降了4.8%。以雪碧样品为基质进行了加标回收试验,回收率为97.6%～102%,测定值的相对标准偏差(n=5)为1.2%。     

FeCl_3/APS复合氧化剂对乳液法合成聚苯胺动力学行为的影响

采用石英晶体微天平(QCM)技术,探讨了以三氯化铁(FeCl3)和过硫酸铵(APS)为复合氧化剂,十二烷基苯磺酸(DBSA)为乳化剂和掺杂剂时,苯胺(An)的乳液聚合动力学行为;并通过对产物的循环伏安分析,初步优化了聚合反应条件.结果表明,An的乳液聚合反应对复合氧化剂、An以及DBSA分别为1,0.5和0.5级.各种条件下的循环伏安(CV)图都显示出PAn的三对氧化还原特征峰.当FeCl3与APS物质的量比为2∶1;氧化剂总量与苯胺的物质的量比为3∶1;DBSA浓度为0.05mol/L时,CV测试的峰电流和电导率最大.     

不同电解质溶液对聚吡咯修饰膜性质的影响

以对甲基苯磺酸钠(p-TSNa)为掺杂剂在不锈钢电极表面恒电位合成聚吡咯(PPy)修饰膜, 采用循环伏安法在-1.6 - 0.8 V大范围扫描研究了修饰膜在H2SO4、Na2SO4、NaOH电解质溶液中的氧化还原行为. 结果表明, 在H2SO4溶液中, 以H+的脱出(氧化)/嵌入(还原)为特征, 并发现聚吡咯在酸性溶液中所特有的质子还原峰. 在Na2SO4和NaOH溶液中, 以Na+的脱出(氧化)/嵌入(还原)峰为特征. FT-IR吸收光谱显示, 经NaOH处理后, 聚吡咯膜的长共轭结构被完全破坏, 而经H2SO4和Na2SO4处后, 膜的共轭结构未发生变化.     

TiO2-WO3负载硅钨酸盐聚苯胺膜电极的电化学行为及电催化性能研究

用循环伏安法制备了金属氧化物(TiO2-WO3)负载硅钨酸盐聚苯胺膜修饰玻碳电极(PAn/SiW12/TiO2-WO3/GC),优化了聚合条件,并对该化学修饰电极的电化学行为,包括溶液pH值的影响和电极的稳定性等进行了研究。研究结果表明,此修饰电极聚合物膜不但保持了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。在0.5 mol/LH2SO4溶液中,该膜电极中的SiW12的第2个还原峰对BrO3-有很好电催化活性,催化过程符合EC平行催化机理。     

过氧化氢在磺酸二茂铁掺杂的聚苯胺上的电催化氧化

在含有磺酸二茂铁溶液中合成的聚苯胺（PAnFc）和不含磺酸二茂铁溶液中合成的聚苯胺（PAn）,在pH 5.0的缓冲溶液中均能催化过氧化氢的氧化,但PAnFc的催化活性高于PAn.催化效应的证据是过氧化氢在裸铂电极上的氧化电位为0.59 V(vs SCE),而在PAnFc电极仅是0.48 V,以及过氧化氢在PAnFc电极上的阳极峰电流是裸铂电极上的5.3倍.根据这种催化特性,用PAn和PAnFc固定葡萄糖氧化酶形成酶电极.实验结果表明,PAnFc酶电极的响应电流比PAn酶电极高得多,而且响应快.这是由于PAnFc在pH 5.0缓冲液中的电化学活性高于PAn,以及掺杂在聚苯胺中的磺酸二茂铁起着重要的电荷传递作用.     

In situ UV-visible spectroelectrochemical evidences for conducting copolymer formation between diphenylamine and m-methoxyaniline

Electrochemical copolymerization of diphenylamine (DPA) with m-methoxy aniline (MA) was carried out in 4 M H(2)SO(4) by cyclic voltammetry (CV). Cyclic voltammograms (CVs) of the copolymer films were recorded in monomer-free background electrolyte. In situ sepectroelectrochemical studies were carried out on an optically transparent electrode (Indium tin oxide (ITO) coated glass) in 4 M H(2)SO(4) for different feed ratios of the comonomers. Constant potential and potential sweep methods were employed for performing polymerization. UV-visible absorption spectra were collected continuously and concurrently during the copolymerization in both the cases. The results from constant potential electropolymerisation indicated the formation of an intermediate with an absorption peak at 576 nm. Derivative cyclic voltabsorptogram (DCVA) was deduced from the results of cyclic spectrovoltammetry. The DCVA derived at 576 nm confirms the intermediates formed during the electrochemical copolymerization. The compositional changes of the two monomers in the copolymers with changes in feed composition of two monomers as predicted from in situ spectro electrochemical studies are evident from elemental analysis. A plausible copolymerization mechanism is suggested.     

碳纸负载电极在乳液法合成聚苯胺电化学性能分析中的应用

首次采用碳纸负载聚苯胺(PAn)为工作电极,探讨了反应时间对乳液法合成PAn电化学性能(循环伏安、交流阻抗及塔菲尔曲线)的影响,并通过对产物电导率、产率及特性粘度的对比分析,印证了产物电化学性能的表征结果.实验结果表明,循环伏安曲线均能有效表征出PAn的三对氧化还原特征峰,交流阻抗曲线均出现一个几乎完整的半圆;且产物的循环伏安、交流阻抗、塔菲尔、产率及电导率随反应时间的变化趋势一致,在反应5h时,PAn的各项性能指标较好.结果显示,利用碳纸作为负载电极,可以对乳液法合成PAn的电化学性能实施有效的实时表征.     

复合酸掺杂导电聚苯胺的性能研究

以苯胺为单体、过硫酸胺为氧化剂,由化学氧化聚合法在磺基水杨酸和硫酸的复合酸的水溶液中合成导电聚苯胺,并通过压片法、激光粒度分析、扫描电镜、差热分析及红外光谱对掺杂态聚苯胺的电导率、表面形貌及结构进行了研究.结果表明,复合酸掺杂聚苯胺的热稳定性比仅用硫酸掺杂聚苯胺的有了很大的提高;所得导电聚苯胺的粒度分布比较均匀(平均粒径约15.4μm);复合酸掺杂使聚苯胺分子链上的电荷呈离域化,掺杂程度提高.     

Template‐free synthesis of polyaniline nanobelts as a catalytic counter electrode in dye‐sensitized solar cells

Polyaniline (PAn) nanobelts were synthesized by simply mixing aniline and hydrochloric acid aqueous solution with ammonium peroxydisulfate and hydrochloric acid aqueous solution at room temperature without any templates. The PAn nanobelt paste with polytetrafluoroethylene as binder is proper for low‐cost and efficient casting processes such as doctor blade method, screen printing, spin‐casting, and even roll‐to‐roll painting. The porous network structure of the PAn nanobelt counter electrode was obtained after drying the paste on the conductive glass. The as‐prepared PAn nanobelt counter electrode showed nearly equivalent electrochemical catalytic activity as that of thermal decomposed Pt counter electrode, owing to the well‐connected conductive network and high active surface area. The power conversion efficiency of dye‐sensitized solar cell with PAn nanobelt counter electrode attained 90% of the value of the cell with Pt counter electrode. Copyright © 2014 John Wiley & Sons, Ltd.     

FTIR spectroscopic characterization of Nafion®–polyaniline composite films employed for the corrosion control of stainless steel

Nafion?–polyaniline (PAn) composite films deposited by a two-step process on a stainless steel (SS) substrate were characterized in this study using Fourier transform infrared (FTIR) spectroscopy under various conditions employed to evaluate their anticorrosion properties. The SS|Nafion? electrode was first prepared by placing a certain amount of Nafion? on the SS substrate, and then polymerization of aniline was carried out potentiodynamically on the SS|Nafion? electrode. The SS|Nafion?–PAn electrodes subjected to both potentiodynamic polarization and open-circuit conditions in sulfuric acid solutions without and with chlorides appeared to have distinct differences in their FTIR spectra. It is proposed that under the electrochemical conditions used in this study, the PAn is mostly formed inside the Nafion? membrane with a high proportion of oligomers influencing the ionic transport through the membrane. The inhibition of pitting corrosion arises primarily from the enhanced permselectivity of the composite film due to the Nafion? membrane that prevents chloride transport. An essential beneficial effect comes also from the PAn redox properties on the growth of the passive oxide film. Even under severe corrosion conditions, Nafion???/em>PAn films retain their redox activity and chemical stability, whereas the membrane crystallinity seems to be enhanced.     

钒(V)化合物在硫酸中的电化学行为研究

应用循环伏安法和旋转环盘电极法研究了H2 SO4 溶液中五价钒化合物 (NH4 VO3和V2 O5)的电化学行为 .由光滑Pt电极测得其CV图 ,两者的基本峰位和峰形都很相似 ,通常出现三个还原峰和三个氧化峰 ,但NH4 VO3多一个氧化峰 ,RRDE测定也出现了四个氧化峰 ,本文分析了这些对应峰的反应 ,并给予初步解释     

FTIR spectroscopic characterization of Nafion®–polyaniline composite films employed for the corrosion control of stainless steel

Nafion®–polyaniline (PAn) composite films deposited by a two-step process on a stainless steel (SS) substrate were characterized in this study using Fourier transform infrared (FTIR) spectroscopy under various conditions employed to evaluate their anticorrosion properties. The SS|Nafion® electrode was first prepared by placing a certain amount of Nafion® on the SS substrate, and then polymerization of aniline was carried out potentiodynamically on the SS|Nafion® electrode. The SS|Nafion®–PAn electrodes subjected to both potentiodynamic polarization and open-circuit conditions in sulfuric acid solutions without and with chlorides appeared to have distinct differences in their FTIR spectra. It is proposed that under the electrochemical conditions used in this study, the PAn is mostly formed inside the Nafion® membrane with a high proportion of oligomers influencing the ionic transport through the membrane. The inhibition of pitting corrosion arises primarily from the enhanced permselectivity of the composite film due to the Nafion® membrane that prevents chloride transport. An essential beneficial effect comes also from the PAn redox properties on the growth of the passive oxide film. Even under severe corrosion conditions, Nafion®–PAn films retain their redox activity and chemical stability, whereas the membrane crystallinity seems to be enhanced.