Polyaniline Base Research Articles

Construction of novel coaxial electrospun polyetherimide@polyaniline core-shell fibrous membranes as free-standing flexible electrodes for supercapacitors

Designing porous and flexible electrodes with excellent electrochemical properties is crucial to fabricate high-performance flexible supercapacitors. Conductive polymer-based electrospun fibers are expected to be an ideal material for constructing flexible electrodes due to the enormous specific surface area, unique pore structure and inherent flexibility. However, the exploration of such electrospun fibers with facile preparation methods and high areal capacitance remains challenging. Herein, a novel polyetherimide@polyaniline core-shell fibrous membranes (PEI@PANI CFMs) is fabricated via simply coaxial electrospinning and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) secondary doping. With the aid of polyetherimide, highly concentrated emeraldine base polyaniline (EB-PANI) can be perfectly wrapped on the surface of fibers without any spinning assistants, ensuring the well-developed pore structures, superior hydrophilicity, good electrical conductivity and outstanding mechanical flexibility. Benefiting from the synergistic effect of structure and constituents, such flexible PEI@PANI CFMs as electrode materials can provide more accessible electrochemical active sites and decrease the ion diffusion resistance. Therefore, the PEI@PANI CFMs present outstanding areal capacitance of 1159.9 mF cm−2 and remarkable energy density of 46.91 μW h cm−2 in the electrodes and symmetric supercapacitors, demonstrating great potential for applications in flexible energy storage field. This fabrication strategy provides a simple and practicable way to manufacture polyaniline-based fibrous membranes for high-performance flexible electrode materials.

POLYANILINE, HALLOYSITE NANOTUBES AND THEIR NANOCOMPOSITE AS ADSORBENTS FOR ORGANIC DYES

This work is devoted to the study of the adsorption efficiency of methylene blue and methyl orange dyes by polyaniline base (PANI), halloysite nanotubes (HNTs), and their nanocomposite (HNTs/PANI). PANI and the nanocomposite were prepared by the chemical oxidative polymerization of aniline in the absence and presence of HNTs followed by subsequent dedoping by ammonia solution. The morphology and thermal stability of the adsorbents were explored. In particular, the TEM method showed that the nanocomposite consisted of practically non-agglomerated nanoparticles with a “core-shell” morphology. Particles of pure polymer are quite agglomerated and form massive aggregates. The kinetics of decreasing the concentration of dyes in solutions upon their contact with adsorbent powders was studied by the method of electron spectroscopy. The HNTs/PANI nanocomposite was found to absorb both dyes with slightly higher efficiency than the PANI base probably due to more developed surface of the former. Processing of the obtained results of adsorption of both dyes on the studied adsorbents according to different kinetic models (pseudo-first and pseudo-second order and intraparticle diffusion) showed that in all cases this process is best described by the pseudo-second order model, which indicates the chemical nature of adsorption. The calculated adsorption capacity of the adsorbents under study appeared be quite close to the experimental one. These materials can be used as effective adsorbents for cleaning wastewaters from organic dyes.

Carbonization of MOF-5/Polyaniline Composites to N,O-Doped Carbon/ZnO/ZnS and N,O-Doped Carbon/ZnO Composites with High Specific Capacitance, Specific Surface Area and Electrical Conductivity.

Composites of carbons with metal oxides and metal sulfides have attracted a lot of interest as materials for energy conversion and storage applications. Herein, we report on novel N,O-doped carbon/ZnO/ZnS and N,O-doped carbon/ZnO composites (generally named C-(MOF-5/PANI)), synthesized by the carbonization of metal-organic framework MOF-5/polyaniline (PANI) composites. The produced C-(MOF-5/PANI)s are comprehensively characterized in terms of composition, molecular and crystalline structure, morphology, electrical conductivity, surface area, and electrochemical behavior. The composition and properties of C-(MOF-5/PANI) composites are dictated by the composition of MOF-5/PANI precursors and the form of PANI (conducting emeraldine salt (ES) or nonconducting emeraldine base). The ZnS phase is formed only with the PANI-ES form due to S-containing counter-ions. XRPD revealed that ZnO and ZnS existed as pure wurtzite crystalline phases. PANI and MOF-5 acted synergistically to produce C-(MOF-5/PANI)s with high SBET (up to 609 m2 g-1), electrical conductivity (up to 0.24 S cm-1), and specific capacitance, Cspec, (up to 238.2 F g-1 at 10 mV s-1). Values of Cspec commensurated with N content in C-(MOF-5/PANI) composites (1-10 wt.%) and overcame Cspec of carbonized individual components PANI and MOF-5. By acid etching treatment of C-(MOF-5/PANI), SBET and Cspec increased to 1148 m2 g-1 and 341 F g-1, respectively. The developed composites represent promising electrode materials for supercapacitors.

Electrochemical properties of aluminum ion batteries with emeraldine base polyaniline as cathode material

Aluminum ion batteries (AIBs) are currently attracting widespread interest due to their high capacity, low price and high safety, while practical applications are severely hampered by the lack of suitable cathodes and the relatively complex and divergent energy storage mechanisms. Polyaniline has shown considerable promise for application in various rechargeable batteries, however, little research has been conducted on the application to AIBs. Here, the emeraldine base polyaniline (PANI) using a chemical oxidation method is synthesized and then assembled in an Al/PANI cell with a chloroaluminate ionic liquid as the electrolyte. Compared with the conventional protonated polyaniline cathode, the PANI cathode shows better electrochemical performance during the 0–2.4 V charging/discharging process, exhibiting a discharge specific capacity of 155 mAh g-1 at a current density of 1 A g -1and capacity retention of 80% after 2000 cycles. Meanwhile, ex-situ characterization reveals a novel conversion process of this system different from that of conventional proton-doped polyaniline materials, in which the electrolyte is spontaneously complexed with the PANI cathode. This is followed by reversible doping of the chloroaluminate anion in the –NH- group of the PANI-AlCl3 complex, yielding high reversible capacity and long cycle life. These findings have made new attempts and laid the foundation for the development of high-performance aluminum ion batteries with conducting polymers as the cathode material and further clarification of their charge storage and reaction mechanisms.

The structural and electrical properties of polyaniline carbon nanotubes (PANI-CNTs) composite

Carbon nanotubes (CNTs) doped polyaniline (PANI) nanocomposite was synthesized by chemical polymerization method in the presence of HCl medium. The structure of the PANI/CNTs composite was confirmed by X-ray diffraction (XRD) technique. The SEM results showed granular and tube like shape for PANI and CNTs respectively. The SEM characterization of PANI-CNTs composite revealed a uniform wrapping of CNTs by PANI forming a core-shell nanostructure. The temperature dependent dielectric measurements were performed in the frequency range of 0.1 kHz-1 MHz. Dielectric measurements revealed the strong interactions between PANI and CNT nanoparticles causing a beneficial effect on stability of the composites. The dielectric constant followed the Maxwell-Wagner interfacial polarization. The frequency dependent conductivity obeyed a power law of frequency. Temperature has an effect on dielectric constant values of composite sample. Heat treatment affected the dipole polarization by reducing the relaxation time and hence contributed to the enhancement of dielectric parameters. Dielectric properties of composites were found to be improved due to addition of carbon nanotubes, which can improve the formation of a more efficient network for charge transport mechanism in the base polyaniline matrix. The border between polyaniline and CNTs can play an important role in yielding a large dielectric constant in the nanocomposites.

Facile preparation of water-dispersible carboxylated polyaniline

Polyaniline (PANI), containing carboxylic groups, was prepared by covalent modification of PANI base, using various amounts of thiolactic acid (TLA). It was found that using the excess of TLA, compared to the stoichiometric amount required for modification of emeraldine form of PANI, did not lead to increase of substitution degree. Elemental analysis showed that in all studied conditions ≈6.5 wt% of carboxylic groups were introduced into PANI backbone. Change of PANI chemical structure as a result of modification by TLA was studied by electronic, vibrational and photoelectron spectroscopy. It was shown that TLA is covalently bound to PANI without significant amount of free TLA and the initial PANI base also becomes partially protonated. Conductivity of PANI-TLA materials (≈5 ×10–7 S cm–1) increased by 4 orders of magnitude, compared to PANI base (5 ×10–11 S cm–1). Due to the presence of carboxylic groups, TLA-modified PANI is dispersible in alkaline aqueous medium, which can enable eco-friendly ways of PANI deposition for the applications in sensors and anticorrosive coatings.

Three‐dimensional MoSx/polyaniline@graphene heteroaerogels as electrode materials for high‐performance symmetric supercapacitors

AbstractNanohybrids of transition metal dichalcogenide (TMDs) with conducting materials such as carbonaceous graphene and conducting polymers like polyaniline (PANI) have attracted significant interest as electrode material in energy storage applications, particularly supercapacitors. Herein, we put forward a simplistic and scalable approach to integrating molybdenum sulfide (MoSx) with conducting graphene and polyaniline supports into a three‐dimensional (3D) assembly. Acidic graphene oxide was simultaneously used as a precursor of graphene and catalyst to in situ synthesize the amorphous molybdenum (MoSx) nanoparticles and as an acidic dopant for polyaniline base to form 3D porous MoSx‐PANI@RGO architecture under hydrothermal methods. Due to its highly porous conductive network and plentiful ion diffusion redox sites, the as‐obtained 3D hybrid material was effectively used to fabricate electrodes for supercapacitor application. The 3D MoSx‐PANI@RGO nanohybrid electrodes showed excellent specific capacitance of 1365 F g−1 @ 1 A g−1, significantly greater than the PANI/RGO (770 F g−1) and MoSx/RGO (568 F g−1) electrodes, respectively. Remarkably, the corresponding symmetric supercapacitor device can deliver an excellent energy density of 29.5 Wh kg−1 and a high‐power density of 8700 W kg−1 with excellent cycling permanence verified by 88% capacitance preservation after 5000 cycles. Overall, the implemented strategy of using direct acidic GO offers technological scalability in fabricating a wide range of low‐cost 3D functional electrodes for various energy‐storage applications.

Effect of Protonation Doping of Polyaniline Electrodes using Hydrochloric Acid on Its Pseudocapacitor Capacitance

Pseudocapacitor is a supercapacitor that can store charge faradically through a reversible redox reaction. Polyaniline (PANi) is one of the promising active materials for pseudocapacitor electrodes since it can produce theoretical specific capacitance up to 750 F/g. We prepared leucomeraldine base polyaniline (LB-PANi) electrodes by deposition of dissolved LB-PANi powder in N,N-Dimethylformamide (DMF) using spraycoating technique. The LB-PANi electrodes was then doped with 1 M HCl through protonation process to obtain emeraldine salt polyaniline (ES-PANi) electrodes. We used both electrode materials and 1 M KCl to prepare a symmetrical sandwich supercapacitor model of <LB-PANi|KCl|LB-PANi> and <ES-PANi|KCl|ES-PANi>, as well as measured their performance. The results show a significant increase of the specific capacitance of PANi supercapacitor from 15.02 F/kg to 1876.87 F/kg when the electrodes of the LB-PANi were changed with the ES-PANi electrodes.

Adsorption kinetics for the removal of toxic Congo red dye by polyaniline and citrus leaves as effective adsorbents

Abstract This study focusses on the synthesis of polyaniline (PANI) and polyaniline base adsorbent utilizing Citrus limon leaves (CL) powder. The polyaniline base adsorbent with C. limon was synthesized using the same process as polyaniline synthesis, but with the addition of leaves powder. PANI and PANI based adsorbent with C. limon leaves powder (PANI/CL) were characterized by Fourier Transform Infra-Red (FTIR), UV-Visible spectroscopy and Scanning Electron Microscopy (SEM). This synthesized material was employed for the removal of congo red (CR) dye from industrial wastewater. Furthermore, the Langmuir, Temkin and Freundlich isotherms were also applied to evaluate experimental results. PANI is an efficient adsorbent for CR removal with 71.9 mg/g, while PANI/CL is an efficient adsorbent with 80 mg/g removal of dye according to a comparison of maximal adsorption capabilities. The data concludes that the prepared adsorbents could possibly be employed for the removal of toxic dyes from industrial effluents at large scale and ultimately could help in improving the environment.

Synthesis and Characterization of Bacterial Cellulose-Polyaniline Composite with Variation of Dopant Concentration

Polyaniline is a type of conductive polymer. Bacterial cellulose has high mechanical properties, so it can be made into polyaniline base composite materials. A stable form of polyaniline oxidation at room temperature is emeraldine base. The emeraldine base has a conductivity value of 10-6 S/cm. Dopants can change the shape of emeraldine base to emeraldine salt by protonation process. Emeraldine salt is a conductive form of polyaniline. The conductivity value of emeraldine salt is 0,03-0,07 S/cm. The addition of dopan in synthesis of polymer was carried out to determine its effect on the conductivity value. The disadvantage of polyaniline is that its mechanical properties are weak and easily brittle. Modifications are needed to improve the mechanical properties of polyaniline, one of which is the manufacture of composite. Bacterial celluloce has high mechanical properties so it can be made into polyaniline base composite materials. Synthesis of bacterial cellulose-polyaniline composites by in situ chemical polymerization methods. Syntehsis is started with BC membrane was dipped into aniline solution for about 2h with stirring at room temperature. The BC was immersed into ammonium peroxydisulfate solution for about 30m with stirring. The bacterial cellulose-polyaniline compositions obtained are black color which is characteristic of the emeraldine salt. The highest conductivity value of composite was obtained from the addition of 3,5M HCl dopant which was 4,70x10-4 S/cm. FTIR analysis of composite obtained peak of the characteristic polyanilin was conductive at 1565,92 cm-1 as C=C quinoid ring and 1442,95 cm-1 as C=C benzoid ring.

Preparation and characterization of some composite phosphate glass-Polyaniline derivatives studying their antimicrobial activity

The present work involved the preparation of mixed composite derivatives from phosphate glass and polyaniline together with additional doped samples containing increasing CuO or ZnO (3→10 mol%). All prepared pure glass and polyaniline together with their composites were characterized by structural FTIR analysis, X-ray diffraction examinations and surface scanning electron microscope (SEM). Further antimicrobial properties of the base glass, base polyaniline and composites with one of the two dopants (CuO,ZnO) were studied and evaluated. FT infrared spectrum of the base undoped glass revealed vibrational bands due to PO4 tetrahedral groups which are extended from 400 cm-1 to 1500 cm-1 within the mid region. The base polyaniline exhibits extended vibrational bands characteristic for vibrations of C – C, C- H, C = C and N – H groupings. The composite (glass + polyaniline) showed mixed or interfering vibrations of all constitutional groupings. The dopant oxides showed only limited variations to the IR spectra. X-ray diffraction patterns of base and doped glass samples revealed only undefined humps with no indication for crystalline species but only amorphous structures. On the other hand, polyaniline revealed two diffraction peaks which were correlated with crystalline components of the polymerized granular texture of the (PANI). SEM investigations revealed mostly amorphous texture for the parent glass and its derivatives but the polyaniline exhibited granular texture which extended to all composites in different forms. Glass and polyaniline composites showed varying responses to micro-organisms. In general, the composites showed favourable data.

Nitrogen-containing carbon enriched with tungsten atoms prepared by carbonization of polyaniline

Polyaniline (PANI) salts with tungstosilicic (TSA) and phosphotungstic acids (PTA) were prepared by reprotonation of PANI base. Partial protonation of the precursor base was confirmed by Raman spectroscopy and by conductivity measurements. Conductivity of polyaniline tungstosilicate (PANI-TSA) and polyaniline phosphotungstate (PANI-PTA) after reprotonation measured on compressed pellets was found to be 1 × 10–5 S cm−1 and 4 × 10–6 S cm−1, that is significantly higher compared to conductivity of PANI base (⁓ 10–11 S cm–1). According to thermogravimetric and elemental analyses, the amount of heteropolyacids in the resulting salts was ≈ 20 wt%, which corresponded to ≈ 15 wt% of tungsten. Tungsten- and nitrogen-containing carbon derivatives were obtained by carbonization of the prepared PANI salts without losing their conductivity (⁓10–7 S cm–1). Successful carbonization was confirmed by vibrational spectroscopy. Electron microscopy showed that globular morphology typical for PANI base was not affected by reprotonation and carbonization procedures. Elemental analysis confirmed 25.6 and 17.9 wt% of tungsten, 9.7 and 9.6 wt% of nitrogen in the carbonized PANI-PTA and PANI-TSA, respectively. The prepared carbon derivatives can be potentially useful for electrocatalysis.

Adsorption of methylene blue onto chitosan–montmorillonite/polyaniline nanocomposite

Eco-friendly adsorbent of chitosan–montmorillonite/polyaniline (CH–Mt/PANI) nanocomposite was synthesized by the intercalation of CH into Mt through ion-exchange process followed by the impregnation of aniline. Then in-situ polymerization of aniline using ammonium peroxydisulfate as an oxidant yielded a conducting polymer, polyaniline, as an additional component. The composite with polyaniline salt was also converted to corresponding CH–Mt/PANI base nanocomposite. The composites were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, thermal gravimetric analysis and electron microscopy and subsequently used for the removal of methylene blue from aqueous solutions. The composite with polyaniline base proved to be better dye adsorbent than that with polyaniline salt and was therefore investigated in detail. The adsorption of the dye onto CH–Mt/PANI base nanocomposite follows the pseudo second-order kinetics and it is well described by Temkin isotherm model. Moreover, the intraparticle diffusion was found to play a significant role in the adsorption mechanism. The maximum adsorption capacity was estimated to be 111 mg g−1, exceeded the adsorption capacities of the individual precursors.

Synthesis, Electrical Conductivity, and Dielectric Behaviour of Polyaniline Doped with H2SO4; HCl and (HCl + NaNO2) Mixture

Acid doped Polyaniline (PANI) due to their increased electrical conductivity, are considered to be the most promising conducting filler materials. Hence, the present study, reports the synthesis of the PANI followed by acid doping, electrical conductivity and dielectric properties measurements of H2SO4; HCl and (Conc. HCl + NaNO2mixture) doped PANI. In order to know the effect of acetone washing on the electrical properties of acid doped PANI samples, the electrical properties of the non-acetone washed acid doped PANI samples are compared with that of their acetone washed counterparts. The PANI salt was prepared by conventional route using aniline hydrochloride and ammonium persulphate as an oxidant. PANI salt was subjected to 0.5M NaOH to form PANI base, which was further doped separately with H2SO4; HCl and (Conc. HCl + NaNO2mixture) respectively followed by acetone washing. A comparative electrical conductivity study between the acetone washed and unwashed PANI salt and H2SO4, HCl and Conc. HCl + NaNO2 mixture doped PANI were characterized by dielectric and impedance study.

A molecular dynamics study of the binding effectiveness between undoped conjugated polymer binders and tetra-sulfides in lithium–sulfur batteries

Full atomistic molecular dynamics simulations are performed on tetra-sulfides and undoped conjugated polymers pernigraniline base polyaniline (PNB), leucoemeraldine base polyaniline (LEB), poly (3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPY) to investigate the binding effectiveness between polysulfides and polymer binders. The weight ratio between sulfur and binder in lithium–sulfur cells is considered in 1:1 v/v mixture of dioxolane/dimethoxyethane. The simulations reveal that the end group 2 of PNB can effectively bind a lithium tetra-sulfide (i.e. Li2S4) cluster or 2 out of 43 Li2S4 molecules with the effect of solvent. However, repeat units of PNB, LEB, PEDOT and PPY seem ineffective in binding solvated Li2S4 through non-bonded interaction, especially when the concentration of tetra-sulfide/binder in a local domain of the cathode is low. Therefore, polymers with this specific functional group (i.e. the end group 2 of PNB) are suggested to be further studied as potential effective binders to inhibit the shuttle effect of solvated lithium polysulfides. Also, since the solvent has considerable impact on the binding effectiveness between tetra-sulfides and binder, it is suggested to take advantage of the explicit solvation models, such as those built in this work, to predict how other influencing factors affect binding between polysulfides and polymers.

Ion beam modification of polyaniline: Optical and electrical properties of Cu+ ion implanted thin films

Ion implantation of thin nanometre scale films is believed to facilitate better control of the material modification process in thin films when compared to mainstream chemical and electrochemical methods. In this work emeraldine base polyaniline (PANI) films on Indium Tin Oxide coated Polyethylene Terephthalate (ITO/PET) substrates were implanted with 50 keV Cu+ ions at liquid nitrogen temperature to fluences between 0.5 × 1016 and 5.0 × 1016 ions/cm2 to form Cu-PANI nanocomposite sublayer regions in the films. UV–vis, PL and I-V measurements were used to investigate changes in optical and electrical properties of the films post ion implantation. UV–vis data shows red shifting of the optical band gap as a function of fluence from 3.12 eV down to 1.41 eV. At higher fluences Local Surface Plasmon Resonance (LSPR) effects are observed due to formation of Cu nanoparticles ((NPs) in the PANI matrix. Photoluminescence spectra show an increase in the emission peak intensity with fluence, suggesting a corresponding increase in the number of available charge carriers due to radiation induced carbon clustering. This is corroborated by I-V data, which shows a decrease in the DC resistance of the films as a function of fluence.

Electropolymerization of aniline monomer and effects of synthesis conditions on the characteristics of synthesized polyaniline thin films

Electrochemical polymerization of aniline was carried on platinum (Pt) wire electrode in sulfuric acid (H2SO4) solution by cyclic voltammetry using a conventional three-electrode cell at room temperature (20°C). The effects on the electrodeposition of the monomer concentration, anodic potential and potential scan rate are discussed. The conductive layer of emeraldine base polyaniline (Pani) was prepared in this work by repeating potential cycling between -0.24 and 0.9 V/SCE at 50 mV/s in 1 M H2SO4 solution containing 0.1 M aniline monomer.

Efficient electrochemical reduction of CO2 to formate using Sn-Polyaniline film on Ni foam

Metals have proved to be cracking catalysts for electrochemical reduction of CO2 to formate (ERCO2F), but they suffer from a high overpotential caused by weak adsorption of CO2. As far as we know, N-containing polymers, with N atoms lowering the activation energy through efficient trapping of CO2, can make contributes to ERCO2F. Here, a composite electrode of metal and N-containing conjugated polymer at the interface was used for CO2 reduction. It exhibited superior Faradaic efficiency (94% ± 1%) and space time yield (306 ± 14 μmol h−1 cm−2) at the electrolytic potential of −1.70 V for electrochemical reduction of CO2 to formate. Polyaniline film was obtained by potentiostatic reduction of pre-completed polyaniline nanowires from polymerizing aniline on Ni foam. Then the spontaneous oxidation of base polyaniline was used to promote the reduction of tin deposition on its surface.

Calculations of oxygen and humidity influence on properties of pernigraniline base polyaniline oligomers

In spite of extensive investigation and applications, influence of oxygen (O), and humidity on polyaniline (PANI) behaviour is not well understood. For this reason we have performed semi-empirical quantum mechanics, and ab-initio calculations of the pernigraniline base (PNB) PANI oligomers, of various lengths, before and after approach of H2O, O2, and hydroxyl (OH−) group, and attachment of OH− and O to various molecular positions. Structure, charge and electrostatic potential distribution, relevant energies and enthalpies, infrared and electronic spectra of the PNB tetramer equilibrium conformation, and their changes induced by specific OH−, and O attachments are determined. These results provide identification of the most probable positions for O2 and H2O approach to PNB_PANI, enthalpies of OH− and O attachments to them, changes of molecular properties induced by the attachments, and infrared and electronic modes that are most suitable for the attachments detection. The results are compared to the existing experimental data, and the results of similar calculations, and implications for the PNB_PANI applications are notified.

Thermally Induced Protonation of Conducting Polyaniline Film by Dibutyl Phosphite Conversion to Phosphate.

The blue thin polyaniline base film changes its color to green after immersion of the film into dibutyl phosphonate. The green color of the film converts to a greenish-blue after heating to 200 °C in air, which is characteristic for the protonated conducting form of polyaniline. This is in contrast to the "standard" polyaniline hydrochloride, which is transformed into a cross-linked polyaniline base under such conditions. To explain this unexpected observation, the interaction of polyaniline base with dibutyl phosphonate at ambient conditions and after heating to 200 °C was studied using UV-visible, FTIR and Raman spectroscopies. On the basis of these studies, we propose that the dibutyl phosphite tautomeric form of dibutyl phosphonate, which interacts with polyaniline base at 20 °C, converts to the oxidized form, dibutyl phosphate, at 200 °C and subsequently protonates the film. Quantum-chemical modeling of the interaction of polyaniline base with dibutyl phosphite and dibutyl phosphate supports this explanation.