Effect Nd2O3 content on electrochemical performance of polyaniline/Nd2O3 composites

Polyaniline/neodymium(III) oxide (PANI/Nd₂O₃) composites were synthesized by in situ chemical oxidative polymerization method, and the new electrode materials were used for supercapacitor. The composites were characterized physically by scanning electron microscope (SEM), Fourier transform infrared spectra (FTIR) and X‐ray diffraction (XRD). SEM, IR and XRD results showed the existence of interactions between PANI and Nd₂O₃. The electrochemical capacitance performance of the composites was investigated by cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy with a three‐electrode system in 6 M KOH solution. Cyclic voltammetry and galvanostatic charge/discharge tests proved that the addition of Nd₂O₃ enhanced the capacitance of the composites. However, the conductivity of the composites decreases with increasing the amount of Nd₂O₃. Electrochemical impedance tests manifest that the charge‐transfer resistance of the composites is smaller than that of the pure PANI, which indicates the addition of Nd₂O₃ could lower resistance and facilitate the charge transfer of the active materials. All results support that Nd₂O₃ has a significant contribution to the performance of PANI and makes the composites have more active sites for faradiac reaction and larger specific capacitance than pure PANI. Copyright © 2014 John Wiley & Sons, Ltd.     

Controllable length adjustment of polyaniline particle with temperature sensitive block copolymer as template

Although the diameter of conductive polymer nanoparticles can be controlled effectively, the uniformity of particle length is still very challenging. In this study, with the temperature‐sensitive block copolymer PS₁₁₁‐b‐PNIPAM₁₁₄ as the template, the morphology and size of polyaniline (PANI) particles had been controllably adjusted through the change of temperature. Additionally, the electrochemical performance of each sample was investigated. After PS₁₁₁‐b‐PNIPAM₁₁₄ was synthesized through the reversible addition‐fragmentation chain transfer radical polymerization (RAFT), with its vesicular micelle as the “template”, the PANI particles with uniform length distribution were prepared successfully at 40°C. The average length of PANI particles after template removal was 254.07 nm with a short tail distribution, which was closer to the average than the standard normal distribution. Electrochemical results of PANI showed that it had good electrochemical activity with fast charge and discharge ability. And, with the current density of 1 A·g^?1, its discharge‐specific capacitance could reach up to 805.61 F·g^?1.     

Synthesis and high electrochemical performance of polyaniline/MnO2-coated multi-walled carbon nanotube-based hybrid electrodes

Multi-layered electrodes which consist of polyaniline (PANI)/manganese dioxide (MnO₂)-multi-walled carbon nanotubes (MWNTs) are prepared as the electrode materials for supercapacitors. MnO₂-MWNTs are made by the in situ direct coating method to deposit MnO₂ onto MWNTs; the core/shell structure of multi-layered fibrous electrodes can also be obtained by PANI coating onto the MnO₂-MWNTs. The effect of PANI coating on the electrochemical performance and cyclic stability of MnO₂-MWNTs is investigated. From the cyclic voltammograms, the PANI/MnO₂-MWNTs show remarkably enhanced specific capacitance and cycle stability compared to MnO₂-MWNTs, where the highest specific capacitance (350 F/g) is obtained at a current density of 0.2 A/g for the PANI/MnO₂-MWNTs as compared to 92 F/g for pristine MWNTs and 306 F/g for MnO₂-MWNTs. This indicates that the improved electrochemical performance of PANI/MnO₂-MWNTs is due to the enhanced electrical properties by nano-scale-coated MnO₂ onto MWNTs and the PANI coating that leads to the increased cycle stability by delaying the dissolution of MnO₂ during charge/discharge tests.     

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.     

Electrochemical polymerization of polyaniline doped with Zn2+ as the electrode material for electrochemical supercapacitors

Polyaniline doped with Zn²⁺ (PANI/Zn²⁺) films was synthesized by cyclic voltammetric method on stainless steel mesh substrates in 0.2 mol L^?1 aniline and 0.5 mol L^?1 sulfuric acid electrolyte with various concentrations of zinc sulfate (ZnSO₄·7H₂O). The structure and morphology of PANI and PANI/Zn²⁺ films were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques, respectively. The electrochemical properties of PANI and PANI/Zn²⁺ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy in 0.5 mol L^?1 H₂SO₄ electrolyte in a three-electrode system. The results show that the surface morphology of PANI/Zn²⁺ is more rough than that of pure PANI. The specific capacitance of the PANI/Zn²⁺ film displays a larger specific capacitance of 738 F g^?1, lower resistance, and better stability as compared with the pure PANI film. Thus, good capacitive performance demonstrates its potential superiority for supercapacitors.     

Single-walled Carbon Nanotubes as Electrode Materials for Supercapacitors

Large-scale synthesized single-walled carbon nanotubes （SWNT） prepared by electric arc discharge method and a mixture of NiO and Y2O3 as catalyst have been used as electrode materials for supercapacitors. N2 adsorption/desorption measurement shows that the SWNT is a microporous and mesoporous material with specific surface area 435 m^2·g^-1. The specific capacitance of the nitric acid treated SWNT in aqueous electrolyte reaches as high as 105 F/g, which is a combination of electric double layer capacitance and pseudocapacitance. The SWNT-based capacitors also have good charge/discharge reversibility and cycling perdurability.     

Engineering Active Sites of Polyaniline for AlCl2+ Storage in an Aluminum‐Ion Battery

The reversible capacity of AlCl₄^? intercalation/de‐intercalation in conventional cathodes of aluminum‐ion batteries (AIBs) is difficult to improve due to the large size of AlCl₄^? anions. Therefore, it is highly desirable to realize the intercalation/de‐intercalation of smaller Al‐based ions. Here, we fabricated polyaniline/single‐walled carbon nanotubes (PANI/SWCNTs) composite films and protonated the PANI nanorods. The protonation endows PANI with more active sites and enhanced conductivity. Hyper self‐protonated PANI (PANI(H⁺)) exhibits reversible AlCl₂⁺ intercalation/de‐intercalation during the discharge/charge process. As a result, the discharge capacity of the Al/PANI(H⁺) battery is twice as high as that of the initial composite films. PANI(H⁺)@SWCNT electrodes also have a stable cycling life with only 0.003 % capacity decay per cycle over 8000 cycles. Owing to the excellent mechanical properties, PANI(H⁺)@SWCNT composite films can act as the electrodes of flexible AIBs.     

Polyaniline Nanotubes Prepared by One-Step Synergistic Polymerization of Aniline and Acrylic Acid

The electrochemical property of electrode materials greatly depends on their morphologies. This report introduces a novel and facile synthesis method for polyaniline (PANI) nanotubes from one-step synergistic polymerization of aniline and acrylic acid in an aqueous solution induced by the addition of ammonium persulfate (APS). The molar ratio of aniline to AA (\begin{document}$X_{\rm{ani/AA}}$\end{document}) is found to have great influence on the morphology of the produced PANI. Hollow PANI nanotubes with an average inner diameter of 80 nm and outer diameter of 180 nm can be mainly produced when \begin{document}$X_{\rm{ani/AA}}$\end{document} is not higher than 1. The electrochemical properties of the prepared PANI nanotubes have been investigated using a three-electrode system. The specific capacitance of PANI nanotubes can reach 436 F/g at a current density of 0.5 A/g in 1 mol/L H\begin{document}$_2$\end{document}SO\begin{document}$_4$\end{document} solution. Furthermore, the specific capacitance of the PANI nanotube maintains 89.2% after 500 charging/discharging cycles at a current density of 0.5 A/g, indicating a good cycling stability.     

磺化碳纳米管改性聚苯胺复合材料的合成与超级电容特性

运用重氮化技术制备了水溶性磺化碳纳米管,在此基础上,以不同直径的磺化碳纳米管(1～2 nm,<8 nm,10～20 nm,30～50 nm)为载体,采用原位氧化聚合方法合成了一系列磺化碳纳米管改性聚苯胺复合材料.红外和紫外-可见光谱分析表明,聚苯胺与磺化碳纳米管之间存在π-π相互作用,并形成了电荷转移复合物;且随着碳纳...     

MWCNTs/metal (Ni, Co, Fe) oxide nanocomposite as potential material for supercapacitors application in acidic and neutral media

Supercapacitive properties of synthesised metal oxides nanoparticles (MO where M = Ni, Co, Fe) integrated with multi-wall carbon nanotubes (MWCNT) on basal plane pyrolytic graphite electrode (BPPGE) were investigated. Successful modification of the electrode with the MWCNT-MO nanocomposite was confirmed with spectroscopic and microscopic techniques. Supercapacitive properties of the modified electrodes in sulphuric acid (H₂SO₄) and sodium sulphate (Na₂SO₄) electrolytes were investigated using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic constant current charge–discharge (CD) techniques. The specific capacitance values followed similar trend with that of the cyclic voltammetry and the electrochemical impedance experiments and are slightly lower than values obtained using the galvanostatic charge–discharge cycling. MWCNT-NiO-based electrode gave best specific capacitance of 433.8 mF?cm^?2 (ca 2,119 F?g^?1) in H₂SO₄. The electrode exhibited high electrochemical reproducibility with no significant changes over 1,000 cyclic voltammetry cycles.     

Pseudo Capacitive Studies of Polyaniline-Carbon Nanotube Composites as Electrode Material for Supercapacitor

This study describes the formation of composites of polyaniline (PANI)-Carbon Nanotube (CNT) using in situ chemical oxidative polymerization of the monomer aniline. The PANI-CNT composites were characterized by FTIR and UV-Visible spectroscopy and XRD method. The surface morphology of the composites was characterized by scanning electron microscopy (SEM). Pseudo-capacitive behavior of deposited PANI over the surface of CNT was investigated by means of cyclic voltammetry. The composite was mixed with activated carbon for making the electrode. The specific capacitance of the prepared electrode was tested by means of a half cell test. The PANI-CNT composite with 0.02 M aniline in initial polymerization solution had the thinnest layer and highest specific capacitance of 597.82 F/g in 1 M H₂SO_4.     

Thermal stability and electrochemical performance of Polyaniline/Pr6O11 composites

In order to describe the influence of Pr₆O₁₁ on thermal and electrochemical performance of polyaniline (PANI), PANI/Pr₆O₁₁ composites were synthesized by in situ polymerization in the presence of sulfosalicylic acid (as dopant). The composites obtained was characterized by scanning electron microscope, Fourier transform infrared spectra, and X‐ray diffraction. The thermal stability of the composites was investigated by thermogravimetry and derivative thermogravimetry. Finally, the comparative analysis on the electrochemical properties of PANI/Pr₆O₁₁ composites electrodes, such as cyclic voltammetry, electrochemical impedance spectroscopy, and constant current charge–discharge test, was conducted under similar conditions. Scanning electron microscope, infrared, and X‐ray diffraction results show that interaction exists between PANI and Pr₆O₁₁, and the composites are more crystalline than pure PANI. Thermogravimetry and derivative thermogravimetry analyses indicate that PANI/Pr₆O₁₁ composites and pure PANI have similar thermal stability. Moreover, the studies regarded to capacitive properties show that the electrochemical performance of the composites is improved greatly when Pr₆O₁₁ is added in small amount. However, with increasing the amount of Pr₆O₁₁, the electrochemical performance of the composites become worse, which indicates a large amount of Pr₆O₁₁ has a negative effect on the capacitance. These results suggest that PANI is still in the conductive form after inserting the Pr₆O₁₁, and the capacitance performance of PANI can be improved only by a low percentage of Pr₆O₁₁. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation of 3D MnO2/Polyaniline/Graphene Hybrid Material via Interfacial Polymerization as High‐Performance Supercapacitor Electrode

MnO₂/polyaniline/graphene composite as a supercapacitor electrode material was synthesized through an interfacial polymerization approach in the interface of oil/water phase. The as‐synthesized MPG is characterized by infrared spectroscopy, XRD, XPS, SEM and TEM, and its electrochemical performance is measured by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The 3D nanostructure of MPG and loose nanorod structure of polyaniline (PANI) coated with round MnO₂ pellets could be clearly observed. The maximum energy density of MPG is 45.4 Wh/kg (at a power density of 67.8 kW/kg) and the highest power density is 229.2 kW/kg (at an energy density of 25.7 Wh/kg). The capacitance retentions after 500 cycles at the scan rate of 5 mV/s for MGP composite and PANI/graphene are 70.4% and 59.1%, respectively, and the capacitance values after 500 cycles are 158.4 F/g and 114.8 F/g, respectively. The improved performance of MPG is due to the 3D nanostructure, loose nanorod structure of PANI and stable support of graphene, which prevent the mechanical deformation effectively during the fast charge/discharge process and facilitate the diffusion of the electrolyte ions into the inner region of active materials. The composite material is very promising for the next generation of high‐performance supercapacitors electrode.     

Synthesis of Iridium Oxide Nanotubes by Electrodeposition into Polycarbonate Template: Fabrication of Chromium(III) and Arsenic(III) Electrochemical Sensor

For the first time iridium oxide (IrO₂) nanotubes are synthesized by electrodeposition in a polycarbonate (PC) template. Potential cycling (90 cycles) between 0.0 and 0.9 V is used for the preparation of IrO_x nanotubes onto the PC template with a pore diameter of 100 nm. Field‐emission scanning electron microscopy (FESEM) images show, that IrO₂ nanotubes with uniform diameters of 110±10 nm and an estimated length of 1–3 µm are formed. The electrochemical properties and the electrocatalytic activity of a glassy carbon‐IrO_x nanotube modified electrode toward Cr³⁺ and As³⁺ oxidation are investigated. Finally, the modified electrode is used for micromolar detection of the proposed analytes using differential pulse voltammetry.     

Electrospun porous MnMoO<Subscript>4</Subscript> nanotubes as high-performance electrodes for asymmetric supercapacitors

MnMoO₄ nanotubes of diameter about 120 nm were successfully synthesized by a single-spinneret electrospinning technique followed by calcination in air, and their structural, morphological, and electrochemical properties were studied with the aim to fabricate high-performance supercapacitor devices. The obtained MnMoO₄ nanotubes display a 1D architecture with a porous structure and hollow interiors. Benefiting from intriguing structural features, the unique MnMoO₄ nanotube electrodes exhibit a high specific capacitance, excellent rate capability, and cycling stability. As an example, the tube-like MnMoO₄ delivers a specific capacitance of 620 F g^?1 at a current density of 1 A g^?1, and 460 F g^?1 even at a very high current density of 60 A g^?1. Remarkably, almost no decay in specific capacitance is found after continuous charge/discharge cycling for 10,000 cycles at 1 A g^?1. An asymmetric supercapacitor fabricated from this MnMoO₄ nanotubes and activated carbon displayed a maximum high energy density of 31.7 Wh kg^?1 and a power density of 797 W kg^?1, demonstrating a good prospect for practical applications in energy storage electronics.     

Synthesis,characterization, thermal,electrical and magnetic properties of polyaniline composites with rare earth gadolinium coordination complex

Novel polyaniline/gadolinium (PANI/Gd) composites were successfully synthesized by “in‐situ” polymerization at the presence of rare earth Gd coordination complex and D‐tartaric acid (an a dopant). It is rarely to find the studies on related field to add rare earth Gd coordination complex as fillers. Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) and scanning electron microscope (SEM) were used to examine the structure and surface appearance characterization of materials. The thermal stability performance of composites was investigated by thermogravimetry and derivative thermogravimetry (TG‐DTG). Electrochemical performance was measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge test. The magnetic property was investigated by physical property measurement system (PPMS). The structure and surface appearance characterization and the magnetic properties jointly demonstrate the polymerization of rare earth Gd coordination complex and PANI–D‐tartrate (DTA) not only simple physical mixing but also chemical mixing. TG‐DTG analysis suggests that thermal stability of PANI/Gd composites is higher than that of PANI–DTA. Electrochemical performance tests and SEM indicate that the composite (PANI/Gd = 3.3:1,mass ratio) has the most regular morphology and best specific capacitance. The magnetization of the composite (PANI/Gd = 3.3:1,mass ratio)is evidently smaller compared with PANI–DTA and rare earth Gd coordination complex. Copyright © 2016 John Wiley & Sons, Ltd.     

活性碳纳米管的制备及其在有机电解液中的电容性能研究

以KOH为活化剂对碳纳米管进行化学活化制备双电层电容器用高比表面积活性碳纳米管. 采用TEM和N₂吸附法表征活性碳纳米管的结构, 采用恒流充放电、循环伏安、交流阻抗等评价其在1 mol•L^－1 Et₄NBF₄/PC中的电容性能. 随活化剂用量增大、活化温度升高和活化时间的延长, 活性碳纳米管的比表面积和比电容都呈增大的趋势. 活化剂用量为3∶1, 800 ℃活化4 h制备的活性碳纳米管的比表面积663 m²•g^－1, 比活化前提高了3倍, 其比电容达57.2 F• g^－1, 比活化前提高了2倍. 将活性碳纳米管的比电容与其比表面积相关联, 发现两者之间具有非常好的线性关系, 并分析了原因.     

Synthesis,characterization, and electrical properties of nanostructural polyaniline doped with novel sulfonic acids (4‐{n‐[4‐(4‐nitrophenylazo)phenyloxy]alkyl}aminobenzene sulfonic acid)

4‐{n‐[4‐(4‐Nitrophenylazo)phenyloxy]alkyl}aminobenzene sulfonic acid (Cn‐ABSA, where n = 2, 4, 6, 8, or 10) as a novel dopant for conducting polymers of polyaniline (PANI) was designed and synthesized. The molecular structure of Cn‐ABSA was characterized with ¹H NMR, Fourier transform infrared, and secondary‐ion mass spectrometry. Nanostructures (nanotubes or nanorods) of PANI–(Cn‐ABSA) were successfully synthesized with a self‐assembly process in the presence of Cn‐ABSA as the dopant. The morphology (shape and size) and conductivity of the resulting nanostructures strongly depended on the number of alkyl groups (n) and, in particular, the addition of water before polymerization. The formed micelles of aniline/Cn‐ABSA/water were proposed to be templatelike in forming PANI–(Cn‐ABSA) nanostructures on the basis of the emulsion properties measured by dynamic light scattering. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3485–3497, 2001     

One‐pot synthesis of polyaniline doped with transition metal ions using H2O2 as oxidant

Polyanilines (PANIs) doped with Zn²⁺ and Cu²⁺ were synthesized by H₂O₂ oxidative polymerization of aniline in the presence of corresponding metal chloride in solution. The products were characterized by elemental analysis, UV‐Vis‐NIR, FTIR and Raman spectroscopies. Scanning electron micrograph was employed to examine the morphology of PANIs fabricated in the presence of different transition metals. Experimental results showed that transition metal ions had been successfully incorporated into the polymer, and there was a strong interaction between the transition metal ions and the PANI chains. The electrical conductivity of PANI doped with Zn²⁺ and Cu²⁺ is 0.37 and 0.21 S/cm, respectively, which is higher than that of HCl doping PANI corresponding to 0.052 S/cm. The cyclic voltammetric study has indicated that incorporation of metal ions in PANI backbone results in increasing of specific capacitance compared to that of HCl doping PANI. Copyright © 2014 John Wiley & Sons, Ltd.     

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.