Electrochemical Properties Of Polyaniline Research Articles

Approach to Significantly Enhancing the Electrochromic Performance of PANi by In Situ Electrodeposition of the PANi@MXene Composite Film.

Electrochromic materials (ECMs) are capable of reversibly adjusting their transmittance or reflectance properties in response to changes in the external biasing voltages. In this study, we enhanced the electrochromic and electrochemical properties of polyaniline (PANi) effectively through the incorporation of MXene Ti2CTx using an in situ composite strategy. This improvement in the electrochromic and electrochemical properties observed can be attributed to the intermolecular forces between the aniline group of PANi and the terminal groups of MXene Ti2CTx sheets. The presence of hydrogen bonds between the PANi monomers and the MXene sheets was confirmed through theoretical calculations and photoluminescence results, which effectively improved the composite interfaces. Additionally, the PANi@MXene composite films were successfully prepared through a simple one-step in situ polymerization process, as verified by SEM and XPS characterization. The electrochemical studies revealed enhanced electronic conductivity, a high ion diffusion coefficient, and a narrow energy redox gap, all contributing to the excellent electrochemical properties observed. Overall, our results demonstrate that the MXene Ti2CTx composition effectively enhances the electrochromic performance of PANi. The PANi@MXene composite films exhibited a high optical modulation range, rapid switching response time, good thermal radiation regulation, and excellent operational stability. This composite strategy significantly improves the performance and practical applicability of ECMs.

The Performance of Polyaniline Electropolymerization at Various Acidic Electrolytes on Gold Electrodes for Electrochemical Biosensor Application

Polyaniline (PANI), a conductive polymer, has been played a significant role as an electrode material for electrochemical biosensor development. In this study, the electrochemical properties of PANI synthesized in two different acid dopants, i.e. 1.0 M HCl and 0.50 M H2SO4using chronopotentiometry, were investigated. The surface morphologies of the PANI modified gold electrodes were observed using SEM and EDS. The PANI electrodeposition times were also considered. The electrochemical characteristics in terms of the peak-to-peak potential separations (ΔEp), the current of the oxidation (Ipa), and reversible redox properties were investigated using cyclic voltammetry. The results showed that the modified electrode with PANI electropolymerization in H2SO4 as a dopant performed significantly better electrochemically than PANI in HCl at all electrodeposition times. In particular, the PANI prepared in H2SO4 with the electrodeposition time of 120 s demonstrated the best performance in terms of electron transfer and reversible redox reaction.

A new Approach on Electrochemical Properties of Poly Aniline and Polymer Binders Impregnated Zn/ZnO Powders as Anodic Electrodes for Energy Storage Devices

A novel battery consisted of Zn/ZnO anode with polymer binders has been developed by the direct mixing method. The influence of PANI on the performances of Zn/ZnO anode surfaces has been studied using cyclic voltammetry, Tafel polarization, and Impedance studies. The additions of PANI have not formed any coatings on Zn/ZnO anodes. However, a thin layer of PANI has formed. XRD studies revealed that influence of PANI on the Zn/ZnO anodes had not shown any significant changes in the hexagonal phase. SEM images confirmed that Zn's dendrite structure is prevented by polymers such as PVP, PVA, and microemulsion of castor oil. The impedance studies have demonstrated that there is a reduction in Rct values accounted for enhanced conductance of Zn/ZnO anodes.

Effect of electrostatic forces control on the structure and properties of polyaniline/graphene oxide nanocomposite

The effects of electrostatic forces (EF), control on the morphology, structure, and electrochemical properties of polyaniline, PANI/graphene oxide (GO), nanocomposites prepared by interfacial electropolymerization (IEP), are studied in this work. FESEM images showed that the IEP method can form the PANI/GO nanocomposites when the EF-control has been found mainly on the PANI nanofibers formation and growth on the GO film surface; and the EF-enhancement can form PANI nanofibers with small nano-diameter, longer length, uniform morphology, high order and well orientation as compared with the EF-reduction-formed sample. The EF-enhancement-formed PANI/GO nanocomposite showed improved electrochemical properties than that of the EF-reduction-formed sample due to the EF-enhancement that enhances the C–N structure for PANI/GO nanocomposite.

Sensitive detection of heavy metal ions: An electrochemical approach

Polyaniline (PANI) is one of conducting polymers (CPs) which has been used widely in various fields of applications. The low cost monomer, red/ox reversibility, existence of various oxidation states, electrical & optical activity, environmental stability, etc. are the characteristic reasons for it. Herein, we report the electrochemically synthesized PANI and its composite with single-walled carbon nanotube (SWNTs) — PANI/SWNTs. The effects of inculcation of SWNTs were studied using the electrochemical properties of PANI and PANI/SWNTs composites, using the electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) for the electro active natures of both. For the study of optical absorption UV–visible (UV–Vis) spectroscopy was used and for morphology the field effect scanning electron mictroscopy (FESEM) was used. The composite PANI/SWNTs exhibited a good electroactive nature and therefore was opted as a sensing platform for the detection of nickel ions. For the selectivity inculcation of the nickel ions, the chelating ligand viz. dimethylglyoxime (DMG) was used for the modification of the composite.

Doping effects of cerium ion on structure and electrochemical properties of polyaniline

AbstractPolyaniline (PANI)/Ce3+ and PANI/Ce4+ composites were successfully prepared by in situ polymerization in an aqueous solution of poly(2‐acrylamido‐2‐methylpropane sulfonic acid) and characterized by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X‐ray photoelectron spectroscopy, SEM, TEM and electrochemical methods. The results showed that the PANI/Ce ion composites had a high degree of sphericity, high electrical conductivity and good electrochemical performance. The conductivity of PANI/Ce(NO3)3 reaches a maximum of 46.76 S cm−1 at 20 wt% of Ce(NO3)3. It is increased by 377% by comparison with that of pure PANI. In particular, the polarization results showed that the corrosion current density (0.47 µA cm−2) and the inhibition efficiency (97%) of PANI/Ce(NO3)3 were better than the results for PANI and PANI/Ce(SO4)2 composite. This suggested that the PANI/Ce(NO3)3 composite has promising applications in conductive materials, anticorrosion coatings and other related fields. © 2017 Society of Chemical Industry

Enhanced electrocapacitive performance for the supercapacitor with tube-like polyaniline and graphene oxide composites

Polyaniline (PANI) is one of the most attractive materials for pseudocapacitors. To enhance the electrolyte diffusion and improve the electrochemical performance of the electrode, the well-designed morphology of PANI is required. Incorporating carbon materials is also benefic on enhancing the cycling stability as well as the mechanical and electrochemical properties of PANI. In this study, a simple solution method is applied to synthesize the particle-deposited tube-like PANI. Due to the well-defined structure, a specific capacitance (CF) of 437.8 F/g is achieved at the current density of 4 A/g. Furthermore, the self-synthesized graphene oxide (GO) is simply mixed with the particle-deposited tube-like PANI to make a more efficient electrocapacitive material. An enhanced CF value of 475.0 F/g is achieved for the optimized PANI/GO electrode, owing to the synergic effects of the pseudo-capacitance from PANI and the functional groups of GO, as well as the electrochemical double-layered capacitance from GO. After conducting 2000 cycles repeated charge/discharge process, the CF retention of 90% and the average Coulombic efficiency of higher than 90% are also attained for the optimized PANI/GO electrode.

Electrochemical Properties of Polyaniline in Aqueous Environments of Iodide and Bromide in the System of Electrochemical Energy Source

The influence on specific discharge characteristics of redox - active iodide and bromide electrolytes of polyaniline as the cathode material in electrochemical energy sources with zinc anode was studied. Electrochemical and capacitive properties of PAN cathode was investigated using galvanostatic, potentiostatic, cyclic voltampermetric and impedance methods. It was established that PAN cathode inherent discharge specific capacity of Ср = 126 A × h × kg-1 with current load і = 103 A × kg-1 in zinc - sulfate electrolyte and Ср = 301 A × h × kg-1 in the same conditions in the presence of KI. Thus there is a reverse transition of various forms of PAN leucoemeraldine / emeraldine, that among the redox electrolyte causes increase in electrical capacitance and conductivity of PAN electrodes in the charged state.

Investigation of polyaniline films doped with Co2+ as the electrode material for electrochemical supercapacitors

H+ and Co2+ ions co-doped polyaniline were synthesized by cyclic voltammetry onto the stainless steel mesh with various concentrations of cobalt chloride (CoCl2 · 6H2O) in electrolyte. The structure and morphology of polyaniline (PANI) and PANI/Co2+ films were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical properties of PANI and PANI/Co2+ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy (EIS) in 0.5 mol L−1 H2SO4 electrolyte in a three-electrode system. The PANI/0.3 M Co2+ film shows a larger specific capacitance of 736 F g−1 at a current density of 3 mA/cm2 and lower resistance compared with the pure PANI film. The results indicated that the PANI/Co2+ films are promising material for supercapacitors.

Electrochemical Properties of PANI as Single Electrode of Electrochemical Capacitors in Acid Electrolytes

The polyaniline (PANI) powder with globular sponge-like morphology was prepared by chemical solution polymerization, and its morphology and chemical structure were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The single electrode of electrochemical capacitor was made using the prepared PANI powder as active material and carbon paper as current collector. Electrochemical properties of PANI as a single electrode in 1 M HCl and 1 M H2SO4 electrolyte solution were tested by galvanostatic charge/discharge (GCD) and cyclic voltammetry (CV) techniques. It has been found that PANI has higher specific capacitance of 302.43 Fg−1, higher specific energy of 54.44 Wh·kg−1 at 0.5 Ag−1, and higher working potential in 1 M HCl than those in 1 M H2SO4.

Electrochemical and spectroscopic study on thiolation of polyaniline

Polyaniline (PANI) is a conducting polymer, easily synthesized and lucrative for many electrochemical applications like ion-selective sensors and biosensors. Thiolated molecules, including biological ones, can be bound by nucleophilic attachment to the polyaniline backbone. These covalently bound thiols add functionality to PANI, but also cause changes in the electrochemical properties of PANI. Polyaniline studied in this work was electropolymerized on glassy carbon electrodes. 2-Mercaptoethanol (MCE) and 6-(ferrocenyl)hexanethiol (FCHT) were used as the thiols to form functionalized films. The films were characterized by cyclic voltammetry (CV), ex situ FTIR and Raman spectroscopies, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The goal of this work was to confirm the thiolation by spectroscopic methods and to study the impact of thiolation on the electrochemical properties of PANI. Our study showed that thiolated PANI has different electrochemical properties than PANI. Although the thiolation partially reduced the PANI backbone it still remained conductive after the thiolation. Detailed understanding of the thiolation process can be very useful for future applications of PANI.

Electropolymerization and characterization of polyaniline, poly(2-anilinoethanol) and poly(aniline-co-2-anilinoethanol)

Applications of conducting polymers to biosensors have recently aroused much interest. This is because these molecular electronic materials offer control of different parameters such as polymer layer thickness, electrical properties and bio-reagent loading, diversity, ease of fabrication and potentially low cost, etc. Polyaniline, poly(2-anilinoethanol) and poly(aniline-co-2-anilinoethanol) preparations are performed with electrochemical (CV) method at room temperature, in a standard three-electrode cell. Homopolymer and the copolymers of aniline and 2-anilinoethanol films were deposited from 1 M acidic aqueous media containing 0.2 M aniline, 2-anilinoethanol by voltammetric sweep between −0.1 and 1 V Ag/AgCl, at 20 mV/s−1. The sweep was stopped after 30 cycles at −0.1 V Ag/AgCl and the working electrode was covered by homopolymer and copolymer of aniline and 2-anilinoethanol. Characterizations of the products were carried out by cyclic voltammograms, UV–visible, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance (EIS) was employed to examine the water absorption of the synthesized polymers to be used in biosensor application. Electrochemical properties of polyaniline, poly(2-anilinoethanol) and poly(aniline-co-2-anilinoethanol) were studied and it is shown that with increased (2-anilinoethanol) content in the copolymer, its electroactivity, conductivity and resistance are reduced, though the processability and adhesion properties improve. The hydrophilicity of polymer film obtained has increased with increasing (2-anilinoethanol) content which leads to salt moving to the surface of steel.

Effect of APS/NaClO Composite Oxidant on Morphology and Electrochemical Properties of Polyaniline Prepared by Emulsion Polymerization

Conductive polyaniline (PANI) was prepared by emulsion polymerization with ammonium persulfate (APS) and sodium hypochlorite (NaClO) as composite oxidant. Whether add the NaClO or not, the morphology and electrochemical properties (cyclic voltammogram and electrical conductivity) of PANI were discussed. Moreover, the effect of the concentrations of APS, sodium dodecylbenzenesulfonate (SDBS) and NaClO on electrochemical properties of PANI was discussed. The experimental results showed that NaClO had an important effect on the morphology of PANI. Compared with the PANI synthesized by APS alone, the PANI synthesized by APS and NaClO composite oxidant has higher redox peak current and higher conductivity (which is about 2.6 times the former). The optimal properties of PANI was achieved when the molar ratio of aniline (An) to APS was 8∶7, the molar ratio of An to SDBS was 10∶4 and NaClO was 5% (w). UV-Vis and FT-IR indicated that the structure of PANI synthesized by composite oxidant was similar to the PANI synthesized by APS alone.

Electrochemical properties of leucoemeraldine, emeraldine, and pernigraniline forms of polyaniline/multi-wall carbon nanotube nanocomposites for supercapacitor applications

We report on the synthesis and electrochemical properties of leucoemeraldine base, emeraldine salt and pernigraniline base forms of polyaniline (PANI) in the form of nanocomposites with MWNTs. The oxidation state of PANI in the composite is controlled by doping and dedoping of the emeraldine salt form of PANI/MWNT composite, which is prepared through chemical polymerization, using oxidizing and reducing agents without changing the morphology of PANI in the composite and is confirmed by ultraviolet–visible spectroscopy (UV–vis) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical and pseudocapacitive properties of the composites are investigated using cyclic voltammetry and analyzed with respect to the oxidation state of polyaniline. The PANI/MWNT nanocomposites show specific capacitance values of 217 F g −1, 328 F g −1 and 139 F g −1 for leucoemeraldine base, emeraldine salt and pernigraniline base, respectively. Electrochemical impedance spectroscopy is performed to explain the different electrochemical properties of PANI in different oxidation states.

Effect of chemical functionalization on the electrochemical properties of conducting polymers. Modification of polyaniline by diazonium ion coupling and subsequent reductive degradation

The electrochemical properties of polyaniline (PANI) can be altered by coupling the polymer with aryldiazonium ions. The ions are synthesized by diazotization of aromatic primary amines (1-aminoanthraquinone, sulphadiazine and 4-cyanoaniline) bearing functional groups which are then linked to the polyaniline backbone. All materials produced are electroactive, suggesting that the reaction involves coupling of the diazonium ion with the aromatic rings and not nucleophilic substitution by the aminic nitrogen of PANI on the aryl cations. The electrochemical properties of the modified polymers are different to those of PANI, likely due to electronic and steric effects of the attached groups. Reductive degradation of the azo linkages, using dithionite ion, removes the attached moieties leaving primary amino groups attached to the polyaniline backbone. In that way, the effect of the attached groups on the electrochemical properties of PANI is eliminated. FTIR spectroscopy measurement of the different polymers supports the proposed mechanism. Using the method a polymer containing redox (anthraquinone) groups, which could be used for charge storage, is obtained. Additionally a material containing sulphadiazine moieties, which can be released in vivo by bacterial activity, is also produced. The molecule is a well-known sulfa drug with bacteriostatic activity. The reaction sequence seems to be of general application to modify polyanilines, by attaching functional groups, and then to produce a PANI backbone bearing primary amino groups. Evidence is presented on the kinetic control of attached group removal.

Electrochemical properties of polyaniline in p-toluene sulfonic acid solution

Polyaniline was deposited potentiodynamically on a stainless steel substrate in the presence of an inorganic acids (sulfuric acid). The electrochemical characterization of the electrode was carried out by means of cyclic voltammetry and electrochemical impedance spectroscopy in the organic acids ( p-toluene sulfonic acid) solution. The results show that polyaniline has a high specific capacitance of ∼431.8 F g −1 at 1 mV s −1, high coulombic efficiency of ∼95.6% at 20 mV s −1, and exhibits a high reversibility. This indicates the promising feasibility of the polyaniline used as an electrochemical capacitor material in the electrolyte of p-toluene sulfonic acid solution especially at high charge–discharge process.

Polyaniline and polyaniline–carbon nanotube composite fibres as battery materials in ionic liquid electrolyte

New battery materials are presented that consist of either a solid polyaniline (PANi) fibre or the same fibre containing carbon nanotubes (CNTs). An ionic liquid ethylmethyl imidazolium bis(trifluoromethanesulfonyl) amide (EMI.TFSA) is used as electrolyte. The electrochemical properties of PANi and PANi/CNT fibres are investigated by means of cyclic voltammetry, a.c. impedance and galvanostatic charge–discharge techniques. A PANi fibre with a CNT content of 0.25 wt.% exhibits a discharge capacity of 12.1 mAh g −1.

Preparation of N-grafted polyanilines utilizing ring-opening copolymerization of epoxide : Tuning of solubility and optical and electrochemical properties of polyaniline

Polyanilines with various degrees of N-grafting have been synthesized by using ring-opening copolymerization of glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane). The obtained polymer has good solubility in common organic solvents. Optical and thermal properties of the N-grafted polyanilines varying with the degree of the N-grafting and length of the graft side chain have been revealed. The polymer received electrochemical oxidation at about 0.40 V versus Ag +/Ag in a CH 3CN solution of 0.10 M LiBF 4.

Electrochemical Polymerization of Aniline in Proton-Free Nonaqueous Media: Dependence of Microstructure and Electrochemical Properties of Polyaniline on Solvent and Dopant

Electrochemical polymerization of aniline in few nonaqueous media containing varying supporting electrolytes is reported. Three different nonaqueous solvents, i.e., dry acetonitrile, dichloromethane, and nitrobenzene containing three different electrolytes; sodium tetraphenylborate (TPB), tetraethylammonium tetrafluoroborate (TETFB), and tetramethylammonium perchlorate (TMAP) are chosen for electrpopolymerization of aniline under potentiostatic mode (2 V vs. Ag/AgCl) and potentiodynamic mode to 2.0 V vs. Ag/AgCl at the scan rate of 100 mV/s). Polyaniline films with seven different microstructures (polymer I to polymer VII) are synthesized. Polymer I and polymer II are made under potentiostatic condition in acetonitrile and dichloromethane containing 0.1 M sodium tetraphenylborate (TPB) and tetraethylammonium tetrafluoroborate, respectively, whereas polymer III is made under similar conditions in acetonitrile containing 0.1 M tetraethylammonium tetrafluoroborate. Polyaniline films of four other microstructures are made under potentiodynamic mode of electropolymerization. Polymer IV, polymer V, and polymer VI are synthesized in acetonitrile, dichloromethane, and nitrobenzene, respectively, containing the same supporting electrolyte, i.e., 0.1 M tetraethylammonium tetrafluoroborate (TETFB), whereas polymer VII is made under similar conditions in acetonitrile containing tetramethylammonium perchlorate (TMAP). The microstructures of polyaniline films are characterized by scanning electron microscopy and cyclic voltammetry. The results show varying microstructures of the films with change in the nature of electroactivity from polymer I to polymer VII. The comparative results on pH sensitivity are reported. © 2002 The Electrochemical Society. All rights reserved.

Polyaniline composites: improving the electrochemical properties by template synthesis

We have been exploring the idea of using the heterogeneous porosity of inorganic (sol-gel silica) and organic (poly(vinylidene fluoride)) films as a template for the preparation of polyaniline composites. The large size pore distribution (~2.5–800 nm) in both template matrices results in a part of the polyaniline growing more ordered than in films synthesized without spatial restriction. Small-angle X-ray scattering and scanning electron microscopy experiments were done to determine the extreme values of the pore diameters. Using other experimental techniques, including cyclic voltammetry, UV-Vis-NIR spectroscopy, electrochemical impedance and chronopotentiometry, we concluded that the electrochemical properties of polyaniline, such as oxidation and reduction charges, diffusion coefficient and charge-discharge capacity, are improved in these composites.