纯相Li_2MnO_3薄膜的制备及作为锂离子电池正极材料的电化学行为

采用固相烧结法制备了纯相Li2MnO3正极材料及靶材,采用脉冲激光沉积(PLD)法在氧气气氛、不同温度下沉积了Li2MnO3薄膜.通过X射线衍射(XRD)和拉曼(Raman)光谱表征了薄膜的晶体结构,采用扫描电镜(SEM)观察薄膜形貌及厚度,利用电化学手段测试了Li2MnO3薄膜作为锂离子电池正极材料性能.结果表明,PLD方法制备的纯相Li2MnO3薄膜随着沉积温度升高薄膜结晶性变好.25℃沉积的薄膜难以可逆充放电,400℃沉积的薄膜具有较高的电化学活性和循环稳定性.相对于粉末材料,400与600℃制备的Li2MnO3薄膜电极平均放电电位随着循环次数的衰减速率明显低于相应的粉体材料.     

MnO_2/聚苯胺复合材料的电化学电容

以P123为模板剂,软模板法制备出纳米MnO2.酸性条件下引入苯胺并聚合,得到了MnO2/聚苯胺复合材料.X射线衍射(XRD)、红外光谱(IR),扫描电子显微镜(SEM)表征观察样品的结构、形貌.循环伏安、交流阻抗、恒电流充放电等测试MnO2/聚苯胺电极的电化学性能.结果表明:引入苯胺改变了样品纳米MnO2的形貌.MnO2/聚苯胺电极比容量高达190.8F·g-1,500次循环电极比容量仅衰减4.7%,库仑效率均保持在97%以上.     

还原氧化石墨烯表面聚苯胺纳米阵列的制备及电化学电容性能

本文以阳极氧化铝(AAO)膜为模板,通过恒电位法在自组装还原氧化石墨烯(rGO)膜表面制备有序聚苯胺(PANI)纳米线阵列。通过拉曼光谱和场发射扫描电子显微镜分别对其结构和微观形貌进行了表征,并对PANI纳米线阵列的电化学电容性能进行了测试。结果表明,rGO膜表面可电沉积PANI,电沉积得到的PANI纳米线阵列具有比PANI薄膜材料更高的电容和比电容。     

基于碳纸电极电化学快速合成聚苯胺纳米纤维

利用碳纸电极,采用循环伏安法、恒电流法和恒电位法等电化学聚合法快速合成了高氯酸掺杂聚苯胺纳米纤维.利用电子显微镜、红外光谱和四探针测定仪等对聚苯胺的微观形貌结构、掺杂度和电导率进行了研究.用循环伏安法对聚苯胺的电化学特征进行了分析.研究发现,3种方法合成的聚苯胺均为纳米纤维状结构,长度达3μm,直径为50~150 nm.其中,循环伏安法合成的聚苯胺纳米纤维的均一性和电导率均优于其它2种方法,其电导率高达5.97 S/cm.另外,聚苯胺合成速率顺序为恒电流法>循环伏安法>恒电位法,且恒电流法合成的聚苯胺纳米纤维电极材料的放电比容量最大(578 F/g),电容性能最好.     

脉冲电流法电解合成聚苯胺

在0.2mol/L苯胺和0.5mol/LH₂SO₄介质中采用脉冲电流法电解合成聚苯胺(PANI)膜.循环伏安研究表明,与恒电流法相比,脉冲电流法制得的PANI膜具有更好的电化学活性.扫描电镜(SEM)对膜层的微观形貌观察发现,这种特殊的聚苯胺膜层呈纳米纤维状结构,不同于恒电流法制取的颗粒状PANI膜.讨论了脉冲通断比和频率对于膜层性能的影响.     

循环伏安法的电扫描方式对苯胺聚合产物形貌影响的观察

在含有0.2 mol.L-1苯胺的0.5 mol.L-1H2SO4溶液中,以扫描速度50 mV.s-1,扫描电位为-0.1~0.9 V,采用循环伏安法(CV),在金属Ti基体上,通过控制扫描方式分别得到了颗粒状、纤维状及管-片状的苯胺聚合产物,分析了形成不同形貌聚苯胺的原因,并通过扫描电子显微镜(SEM)、循环伏安法和电化学阻抗谱(EIS)对不同形貌聚苯胺的结构和性能进行了表征.结果表明,不同形貌聚苯胺的形成是由于聚苯胺的成核及生长模式不同,而无论何种形貌的聚苯胺膜都具有很大的比表面积和良好的导电性能,其中,管-片状聚苯胺的膜层阻抗最小,导电性能最好.     

原位聚合沉积聚苯胺薄膜及其电致变色性能

采用原位聚合的方法,以水溶性高分子聚乙烯吡咯烷酮(PVP)为空间稳定剂,直接在玻璃基体表面聚合沉积导电聚苯胺(PANI)薄膜。用扫描电镜(SEM)、紫外可见光谱(UV-Vis)、四探针电导率测试仪和热重分析仪(TG)对聚苯胺膜结构及性能进行了表征。采用循环伏安法测试了薄膜的电致变色性。结果表明:盐酸掺杂聚苯胺薄膜呈翠绿色,薄膜厚115 nm,表面电导率为4.6×10-3S/cm。电致变色实验中聚苯胺电极电位在-6~ 6 V循环变化时,薄膜颜色在黄绿和蓝绿间可逆变化。电致变色前后聚苯胺薄膜的紫外可见吸收光谱表明,随着电极电位的降低,极化子峰发生红移,说明聚苯胺分子链中醌式结构单元被还原,聚苯胺薄膜质子化程度提高。     

脉冲激光法制备修饰纳米Eu_2O_3/聚苯胺导电杂化薄膜

采用聚焦脉冲激光法(PLA-IT/SFL)制备修饰纳米Eu2O3/聚苯胺有机溶胶及其杂化薄膜材料。考察了制备条件对修饰纳米Eu2O3/聚苯胺有机溶胶荧光性能的影响。TEM显示Eu2O3粒子粒径约为15 nm且其在聚苯胺中有较高的稳定性。荧光光谱表明该杂化薄膜材料在紫外光照射下发出强烈的红光,且荧光强度达2.53×105a.u。杂化薄膜材料的电导率为1.13×10-2S.cm-1。热分析表明该杂化薄膜比导电性聚苯胺(PAN-HCSA)薄膜具有更好的热稳定性。该杂化薄膜材料可望用于电致发光领域。     

顺序加料法制备聚苯胺与聚吡咯复合物及其电化学电容性能

以顺序加料原位聚合法化学氧化制备了聚吡咯(PPy)和聚苯胺(PANi)的复合物.采用SEM、红外光谱表征其结构,采用电化学工作站测试其超级电容性能.结果表明:制得的聚苯胺与聚吡咯的复合物,形成了二次结构;复合物的循环伏安特性曲线均接近于理想的矩形,恒流充放电曲线基本为线性,呈现双电层电容;PANi-PPy和PPy-PANi复合物的最高比电容分别达到227.6、195.5 F/g.     

不同掺杂酸对纤维聚苯胺电化学性能的影响

采用界面聚合法通过不同质子酸掺杂分别制备了平均直径约为50,62,95nm的纤维聚苯胺。通过傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、透射电镜(TEM)对其化学组成和微观形貌进行了表征,采用循环伏安、恒流充放电和交流阻抗研究了不同质子酸掺杂纤维聚苯胺的超级电容器电容行为,并利用X射线衍射(XRD)、氮气吸脱附及X射线光电子能谱(XPS)等方法对纤维聚苯胺的微观结构进行了深入研究。结果表明:高氯酸(HClO4)掺杂制备的聚苯胺在0.5A/g电流密度下的比容量可以达到397F/g,高于盐酸(HCl,334F/g)和樟脑磺酸(HCSA,383F/g)掺杂聚苯胺的测试结果,纤维的电化学性能主要受其规整度、孔隙率及掺杂度的影响。     

Influence of duty cycle on the structure and electrocatalytic properties of pulse electrodeposited lead dioxide electrodes

In this work, PbO₂ electrodes were prepared by pulse electrodeposition in the lead nitrate plating bath. Effects of duty cycle on the morphology and phase structure were investigated by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the decrease of duty cycles decreases the grain size of PbO₂ electrodes. The steady-state polarization curves and accelerated life tests demonstrate that the oxygen evolution overpotential and service life of PbO₂ electrodes increase with the decrease of duty cycle, the PbO₂ electrodes prepared at 20 % duty cycle possess highest oxygen evolution overpotential and service life, and the service life of PbO₂ electrodes prepared at 20 % duty cycle reaches 71 h which is almost two times longer than that of the PbO₂ electrodes prepared by direct electrodeposition. The bulk electrolysis shows that the methyl orange (MO) degradation on the PbO₂ electrodes prepared by pulse electrodeposition is the pseudo-first-order reaction and the chemical oxygen demand and MO removal on PbO₂ electrodes increase with the decrease of duty cycle, which can be attributed to the higher oxygen evolution overpotentials and electrochemical active surface area of PbO₂ electrodes.     

基底材料对脉冲电流法制备的聚苯胺膜性能的影响

本文采用脉冲电流法(PGM)在不同的基底材料表面沉积PANI, 通过平均电位\|时间曲线及扫描电子显微镜(SEM)等方法研究了基底材料对PGM法制备PANI的影响; 并采用循环伏安(CV)和电化学阻抗谱(EIS)研究了不同电极材料表面PANI的电化学性能.     

纳米纤维聚苯胺膜在不锈钢电极表面的生长过程

研究了脉冲电流法(PGM)聚合苯胺时, 纳米纤维聚苯胺(PANI)膜在不锈钢(SS)电极表面的生长过程. 用计时电位法和扫描电子显微镜(SEM)表征了聚苯胺生长过程的电化学特征和微观形貌; 并通过循环伏安(CV)法研究了苯胺的聚合速率. 结果表明, 聚苯胺的生长经历了两个阶段, 首先是在裸不锈钢电极表面上形成颗粒状聚苯胺, 此时聚合电位约为1.10 V, 经历了30 s后, 电极表面被一层颗粒状聚苯胺膜所覆盖; 在此基础上, 聚苯胺以纳米纤维状结构继续生长, 当颗粒状聚苯胺被纳米纤维状聚苯胺膜完全覆盖时, 聚合电位降至0.75 V左右并保持稳定.     

聚合时间对染料敏化太阳能电池中聚苯胺对电极结构和性能的影响

采用恒电压方法, 以掺杂氟的SnO₂ (FTO)导电玻璃为基底, 采用不同的聚合时间制备SO₄^2?掺杂的聚苯胺对电极(PANI CEs). 利用扫描电子显微镜(SEM)、紫外-可见(UV-Vis)吸收光谱、循环伏安法(CV)和电化学阻抗谱(EIS)等技术详细研究了聚合时间对PANI CEs的表面形貌、结构(如掺杂度、共轭性、氧化态等)和对I^?/I^3?的催化活性的影响. SEM结果表明PANI在FTO上的生长分两个阶段. 适当增加聚合时间可以增加PANI CEs的比表面积, 为催化I^?/I^3?反应提供更多的活性位点, 同时聚苯胺链的共轭性、半氧化态聚苯胺(EB)结构的含量和对阴离子SO₄^2?的掺杂度会随着增加, 进而PANI 的导电率也逐渐增大. 然而, 聚合时间过长会引起薄膜厚度的增加和氧化结构的过多, 使PANI CEs的导电率降低, 电子在PANI 薄膜中的传输阻抗增加, 进而影响其对I^?/I^3?的催化性能. 聚合时间为300 s 时制备出的PANI 薄膜作为染料敏化太阳能电池(DSSCs)对电极和以D149 为染料时, 获得的最高电池光电转换效率为5.30%, 可达到基于Pt 对电极电池效率的88%. 因此, 通过电化学方法制备的PANI CEs有望代替贵金属Pt CEs用于DSSCs中.     

Effects of duty cycle on the preparation and property of PbO<Subscript>2</Subscript>-CeO<Subscript>2</Subscript> nanocomposite electrodes

PbO₂-CeO₂ nanocomposite electrodes were prepared by pulse electrodeposition in the lead nitrate solution containing CeO₂ nanoparticles with different duty cycles. The effects of duty cycle on the morphology and phase structure were investigated by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the decrease of duty cycle can reduce the grain size of PbO₂-CeO₂ nanocomposite electrodes and make the electrodes more compact. The CeO₂ content in composite electrodes increases with the decrease of duty cycle. The steady-state polarization curves and accelerated life tests demonstrate that the oxygen evolution overpotential and service life of PbO₂-CeO₂ nanocomposite electrodes increase with the decrease of duty cycle. The service life of PbO₂-CeO₂ nanocomposite electrodes prepared with 25 % duty cycle reaches 218 h which is 1.8 times longer than that of PbO₂-CeO₂ nanocomposite electrodes prepared by direct electrodeposition. The bulk electrolysis shows that the degradation of malachite green (MG) on the PbO₂-CeO₂ nanocomposite electrodes is the pseudo-first-order reaction and the MG and chemical oxygen demand (COD) removal efficiency on PbO₂-CeO₂ nanocomposite electrodes increases with the decrease of duty cycle, which can be attributed to the higher oxygen evolution overpotentials, electrochemical active surface area, and CeO₂ content in the composite electrodes.     

Studies on morphology of polyaniline films formed at liquid–liquid and solid–liquid interfaces at 25 and 5 °C,respectively, and effect of doping

It is well accepted that the morphology of the nanomaterials has great effect on the properties and hence their applications. Therefore, morphology of materials has become a focus of research in the scientific world. The present study shows that interfacial polymerization and subsequent self-assembly provides a control over the morphology, nanorod/nanosheet, of polyaniline (PANI) films synthesized by liquid–liquid interface reaction technique and solid–liquid interface reaction technique. The synthesized PANI films and its particulate structure are characterized by using various spectroscopic techniques such as UV–visible, ATR-IR, Raman and XPS. The study confirmed the formation, the structure, the size and shape of particles and morphology of PANI by using analytical techniques namely, SAED, SEM and TEM. An important observation is that doping with HCl significantly improves the nanorod formation at the interface. The doped PANI electrode exhibits a higher area with rectangular shape in CV cycle and better cycle stability when compared with the performance of undoped PANI films. We believe that the results of these studies can give valuable leads to manoeuvre formation of PANI films with desired morphology for various applications.

Preparation and electrocatalytic property of lead dioxide prepared by pulse electrodeposition with different pulse current density

Lead dioxide electrodes were prepared by pulse electrodeposition in the lead nitrate solution with different pulse current density. The effects of pulse current density on the morphology and structure of lead dioxide electrodes were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the increase of pulse current density can make the morphology more fine, and the crystal size of lead dioxide decreases with the increase of pulse current density. The anodic polarization curves demonstrate that the oxygen evolution overpotentials of lead dioxide electrodes also enhance with the increase of pulse current density. The stability of lead dioxide electrodes enhances with the increase of pulse current density until 15 mA cm^–2, then the stability decreases. The electrocatalytic property of lead dioxide electrodes was examined for the electrochemical oxidation of rhodamine B (RhB). The results show that the RhB removal efficiency on the lead dioxide electrodes increases with the increase of pulse current density, which can be attributed to the increase of oxygen evolution overpotential.     

Synthesis and characterization of polyaniline/silicon dioxide composites and preparation of conductive films

The focus of this study was to synthesize the inherently conductive polymer polyaniline using an optimized process to prepare polyaniline/silicon dioxide (PANI/SiO₂) composites by in situ polymerization and ex situ solution mixing. PANI and PANI/SiO₂ composite films were prepared by drop‐by‐drop and spin coating methods. The electrical conductivities of HCl doped PANI film and PANI/SiO₂ composite films were measured according to the standard four‐point‐probe technique. The composite films exhibited an increase in electrical conductivity over neat PANI. PANI and PANI/SiO₂ composites were also investigated by spectroscopic methods including UV‐Vis, FT‐IR, and Photoluminescence. UV‐Vis and FT‐IR studies showed that SiO₂ particles affect the quinoid units along the polymer backbone and indicate strong interactions between the SiO₂ particles and the quinoidal sites of PANI (doping effect). The photoluminescence properties of PANI and PANI/SiO₂ composites were studied and the PANI/SiO₂ composites showed increased intensity as compared to neat PANI. The increase of conductivity of PANI/SiO₂ composite may be partially due to the doping or impurity effect of SiO₂ where the silicon dioxides compete with chloride ions. The morphology of particles and films were examined by a scanning electron microscope (SEM). SEM measurements indicated that the SiO₂ were well dispersed and isolated in composite films. Copyright © 2009 John Wiley & Sons, Ltd.     

The effect of the polyaniline morphology on the performance of polyaniline supercapacitors

The polyaniline (PANI) prepared by the pulse galvanostatic method (PGM) or the galvanostatic method on a stainless steel substrate from an aqueous solution of 0.5 mol/l H₂SO₄ with 0.2 mol/l aniline has been studied as an electroactive material in supercapacitors. The electrochemical performance of the PANI supercapacitor is characterized by cyclic voltammetry, a galvanostatic charge–discharge test and electrochemical impedance spectroscopy in NaClO₄ and HClO₄ mixed electrolyte. The results show that PANI films with different morphology and hence different capacitance are synthesized by controlling the synthesis methods and conditions. Owing to the double-layer capacitance and pseudocapacitance increase with increasing real surface area of PANI, the capacitive performances of PANI were enhanced with increasing real surface area of PANI. The highest capacitance is obtained for the PANI film with nanofibrous morphology. From charge–discharge studies of a nanofibrous PANI capacitor, a specific capacitance of 609 F/g and a specific energy density of 26.8 Wh/kg have been obtained at a discharge current density of 1.5 mA/cm². The PANI capacitor also shows little degradation of capacitance after 1,000 cycles. The effects of discharge current density and deposited charge of PANI on capacitance are investigated. The results indicate that the nanofibrous PANI prepared by the PGM is promising for supercapacitors.     

聚噻吩在离子液体中的电化学合成研究

Polythiophene（PTh）films were prepared by the direct electropolymerization of thiophene in the ionic liquid,1-butyl-3-methylimidazolium hexafluorophosphate（BMIM）PF6 . The structure and morphology of PTh films were characterized by means of the FT-IR spectrum and the scanning electron microscopy（ SEM）. The electrical and electrochemical properties of PTh films were examined with the UV-Vis spectrum,cyclic voltammetry（CV） and four-probe method. The results showed that when the potential for electropolymerization was controlled between +1.7 and +1.9 V（vs. Ag/AgCl）,very homogeneous PTh films could be prepared in the ionic liquid （BMIM）PF6 used as solvent and electrolyte. The de-doping（reduction）and re-doping（re-oxidation）of the PTh film prepared in ionic liquid are reversible and stable,and the conductivity of PTh films is 0.01-0.1 S/cm.