PANI Film Research Articles

Fabrication and Characterization of Aluminum-doped ZnO/PANI Hybrid Solar Cells

We report a facile method to fabricate an AZO/PANI heterostructure by a sandwiching technique. Aluminum-doped ZnO (AZO) films were deposited onto indium tin oxide (ITO) glass using the sputtering technique while PANI films were deposited onto ITO glass using electropolymerization. The optoelectric properties of the inorganic/organic device were characterized

Morphology Evolution of Polyaniline Microstructures via Reverse Micelles and Their Hydrophobicity

Polyaniline morphology evolution in toluene has been observed for the first time. Various structures, including one-dimensional open-ended microtubes, three-dimensional solid microspheres and two-dimensional novel solid microplates were controllably synthesized in the same reaction system. The structures obtained were sensitive to oxidant concentration and molar ratio of monomer to oxidant. Solid microplates were mainly formed on the glass beaker wall and bottom, while tubes and spheres were produced in solution by employing reverse micelles as soft templates. Studies on the effect of reaction temperature, mechanical stirring and the addition of more acid were also carried out. FTIR and UV-Vis results showed that the PANI products were in the emeraldine form. The PANI film prepared from spheres exhibited hydrophobic property due to its rough surface covered with nanoscale dots and the large distribution of sphere diameters.

Towards the upper bound of electrochemical performance of ACNT@polyaniline arrays as supercapacitors

A strategy in the rational design of the aligned carbon nanotube @ polyaniline (ACNT@PANI), arrayed on metal foils as supercapacitors, has been demonstrated towards the upper bound of the specific capacitance, namely a high surface area and nanometre thickness of PANI, good accessibility of ions and a low contact resistance. The structure of ACNT@PANI nanoelectrode arrays was investigated and correlated to the surface redox reaction, electronic and ionic transport and thus to the energy and power density of the supercapacitors. The thickness of the PANI film on each ACNT was found the most important parameter, which was optimized to achieve the specific capacitance (∼1100 F g−1) of PANI close to the maximum theoretic value. A prototype supercapacitor was assembled, and a practical application was demonstrated. This device shows a higher specific capacitance, a higher specific power and a lower internal resistance but reduced cost and volume than conventional two-plate supercapacitors, which may provide opportunities for a smarter design of energy storage devices.

In situ electrochemical polymerization of a nanorod-PANI–Graphene composite in a reverse micelle electrolyte and its application in a supercapacitor

Highly porous nanorod-PANI-Graphene composite films were prepared by in situ electrochemical polymerization onto an ITO substrate in a reverse micelle electrolyte. The morphology and microstructure of the composite films were analyzed by using a field emission scanning electron microscope. It was observed that the films were highly porous and the nanorod PANI films were inserted by graphene nanosheets. This indicated that a good conductive network between PANI nanorods and graphene sheets was formed. Further electrochemical tests involved cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1 mol L(-1) HClO(4) solution. The results showed that the composite film had a favorable capacitance with a high electron transfer rate and low resistance. The highest specific capacitance that could be achieved was as high as 878.57 F g(-1) with the charge loading of 500 mC at a current density of 1 A g(-1). The GCD at different charge loadings showed good cycle stability with a low fading rate of specific capacitance after 1000 cycles. The results demonstrated that the nanorod-PANI-Graphene composite was proved to be of great potential as an electrode material for supercapacitors.

Engineered doped and codoped polyaniline gas sensors synthesized in N,N,dimethylformamide media

Conducting Polyaniline films (Pani) on Corning glass substrates, produced using either an in-situ doping process or a co-doping process, were prepared by the oxidative polymerization of aniline in N,N,dimethylformamide. Bicyclic aliphatic camphorsulfonic acid (CSA), aromatic toluenesulfonic acid (TSA) and carboxylic trifluoroacetic acid (TFA) were employed as doping agents, and CSA mixed with TSA and CSA mixed with TFA were employed as the co-doping materials. The topography of the Pani films was analyzed by atomic-force microscopy (AFM), and their doping and oxidizing states were characterized by Fourier-transform infrared (FT-IR) spectroscopy and optical (UV-Vis) spectroscopy. Flower-like clusters, microfibers, and nanofibers were obtained by doping with CSA, TSA, and the mix of both (CSATSA), respectively. The flower-like morphology limits the conductivity of the film while the microfiber morphology leads to a highly conductive film. The conductivity of the films increases with the doping level, coil-like conformation of the chain and the protonation of the imine in quinoid units. The codoped process reduces the roughness of the CSA-doped films by 50%, but the conductivity depends on the acid type used for this process (TSA or TFA). The optical gas sensor response of the films is related to both the morphology and the degree of protonation. In this study, Pani with a microfiber morphology obtained from TSA-doping is the most sensitive to ammonia gas sensing, and Pani with flower-like morphology is the least sensitive.

Polyaniline nanofibers supported on titanium as templates for immobilization of Pd nanoparticles: A new electro‐catalyst for hydrazine oxidation

AbstractPalladium nanoparticles (Pd‐NPs)/polyaniline (PAni)/titanium (Ti) catalysts were prepared using electroless deposition of Pd‐NPs on PAni matrixes coated on Ti substrate. PAni/Ti electrodes were synthesized by electro‐polymerization of aniline on Ti. The morphology of Pd‐NPs on PAni/Ti electrodes were characterized by scanning electron microscopy technique and results indicated that Pd‐NPs were uniformly dispersed on the surface of PAni film. The electro‐catalytic properties of Pd‐NPs/PAni/Ti catalysts toward oxidation of hydrazine were investigated by different electrochemical methods and results showed that Pd‐NPs/PAni/Ti catalysts have high electrochemical activity. In addition, the mechanism of hydrazine electrochemical oxidation catalyzed by Pd‐NPs/PAni/Ti was investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Thermal stability of HCl‐doped‐polyaniline and TiO2 nanoparticles‐based nanocomposites

AbstractElectrically conductive HCl doped polyaniline (Pani) : titanium dioxide (TiO2) nanocomposites thin films were prepared by in‐situ oxidative polymerization of aniline in the presence of different amounts of TiO2 nanoparticles. Later film casting was done using N‐Methyl‐2‐pyrrolidone (NMP) as a solvent. The formation of Pani : TiO2 nanocomposites were characterized by Fourier Transform Infra‐Red spectroscopy (FTIR), x‐ray diffraction (XRD) and thermogravimetric analysis (TGA). The stability of the nanocomposites in terms of direct‐current electrical conductivity retention was studied in air by isothermal and cyclic techniques. The films of Pani : TiO2 nanocomposites were observed thermally more stable under ambient environmental conditions than pure polyaniline film. The stability was seen to be highly dependent on the content of TiO2 nanoparticles in the nanocomposite films. Due to their high stability, such type of nanocomposites can find place as a replacement material for pure polyaniline in electrical and electronic devices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effect of Manganese Ions on Corrosion Inhibition of PANI for Mild Steel in 0.5 M H<sub>2</sub>SO<sub>4</sub>

Manganese ions doped Pani films were prepared by using a cyclic voltammetry technique on mild steel substrate. Corrosion resistances performances of them in 0.5 M H2SO4 solution were obtained by using electrochemical impedance spectroscopy (EIS), polarization curve, and SEM method. The results showed that manganese ions doped Pani particles became smaller and tighter, the resistance reduced, and the corrosion potential rose than Pani in H2SO4 solution.

Gradient Doping of Conducting Polymer Films by Means of Bipolar Electrochemistry

In this paper, we report a novel electrochemical doping method for conducting polymer films based on bipolar electrochemistry. The electrochemical doping of conducting polymers such as poly(3-methylthiophene) (PMT), poly(3,4-ethylenedioxythiophene) (PEDOT), and poly(aniline) (PANI) on a bipolar electrode having a potential gradient on its surface successfully created gradually doped materials. In the case of PEDOT film, the color change at the anodic side was also observed to be gradually transparent. PANI film treated by the bipolar doping gave a multicolored gradation across the film. The results of UV-vis and energy dispersive X-ray analyses for the doped films supported the distribution of dopants in the polymer films reflecting the potential gradient on the bipolar electrode. Furthermore, the reversibility of the bipolar doping of the PMT film was demonstrated by a spectroelectrochemical investigation.

Synthesis and Characterization of Polyaniline Film

The electrochromic PANI film was prepared by emulsion polymerization with dodecyl benzene sulphonic acid (DBSA) as dopant and ammonium persulfate (APS) as initiator. Ultrasonic dispersion was adopted in the polymerization. The electrochemical properties, the surface morphology and structure of the prepared PANI film was characterized by means of Fourier Transform infrared spectroscopy (FT-IR), cyclic voltammograms (CV) and field emission scanning electron microscope (FE-SEM), respectively. The relationship between the morphology and properties of PANI film was detailedly discussed. The PANI film exhibited an excellent electrochromism with reversible color changes form yellow to purple. The PANI film also had quite good reaction kinetics with fast switching speed, and the response time for oxidation and reduction were 65 ms and 66 ms, respectively.

Metal-Dispersed Polyaniline Electrodes for the Anodes of the Direct Ethanol Fuel Cell

To develop better and less expensive electrocatalysts for the oxidation of ethanol in direct ethanol fuel cells, several combinations of a conductive polymer polyaniline, dispersed Pt particles and pre-dispersed metal particles, such as Sn and Fe, were examined. The electrocatalytic activity of the Pt particles was remarkably enhanced when the particles were dispersed on PANI films. The activity strongly depended on the morphology and the electrical conductivity of the five PANI films with different dopant anions: SO42-, NO3- and Cl-. The highest activity was achieved for the SO42--doped PANI film. To reduce the dispersed amount of the expensive Pt particles, inexpensive base metal particles were pre-dispersed on the PANI film, and the Pt particles were then dispersed on the film. The highest activity was obtained with Sn particles. This meant that utilizing dispersed Sn particles could reduce the dispersed amount of the Pt particles needed.

PbS/CoS–Pani composite semiconductor films

The synthesis and characterization of polyaniline (Pani) films embedded with PbS/CoS core–shell, having semiconductor characteristics are reported in this study. Mn 2+ doped, PVA capped PbS/CoS core-shell particles dispersed in Pani matrix served as photoluminescent boosters. The absorption intensity of the core-shell particles–Pani hybrid increased significantly with wide spectrum response and hypsochromic effect. The Mott–Schottky plot showed a negative slope for PbS/CoS-Pani film, indicating typical p-type semiconductivity. The Tauc plot for PbS/CoS-Pani film revealed the direct transition type with a band gap of 2.36 eV. Solid state photovoltaic cells have been fabricated with PbS/CoS-Pani as the hole conductor. The cells show photocurrent of 0.93 mA/cm 2, voltage of 432 mV and energy conversion efficiency of 0.93%. The scanning electron micrograph revealed periodic arrangement in the polymer matrix. This arrangement of the core-shell particles in the continuous polymer matrix with high carrier density promises this material for the photoelectrochemical applications.

A formal representation of the anodic voltammetric response of polyaniline

It is presented a formal representation of the oxidation of Polyaniline (Pani) films that allows fitting the experimental voltammetric current-potential response of Pani modified electrodes. The model includes interactions between the redox centers and takes into account both the faradaic and the capacitive current contributions to the total voltammetric response. Although the separation of both contributions is not possible by just voltammetric techniques, the present formalism allows completely characterizing the voltammetric anodic behavior of conducting polymers. Its suitability is proved to represent the current-potential response of Pani films of different thickness in 3.7 M H 2SO 4 solutions.

Thin polyaniline and polyaniline/carbon nanocomposite films for gas sensing

We have studied the gas sensing properties of five polyaniline-based materials—thick and thin PANI films, nanocomposite PANI/MWNT and PANI/SWNT films, and PANI nanogranules embedded in a polyvinylpyrrolidone matrix. The films (except for the latter) were deposited within the induction period of the polymerization process on gold interdigitated micro electrodes. Their sensitivity to NH 3, H 2, ethanol, methanol, and acetone was measured. The thin PANI film (~ 100 nm thick) prepared by a lift-off process had the sensitivity to ammonia below 0.5 ppm, which was higher than that of nanocomposite films. Two materials—thick PANI film and nanocomposite PANI/MWNT film—exhibited a shallow minimum in the temperature dependence of resistance (at 313 K and 319 K), which is a feature exploitable in practical applications, since the gas sensors should be insensitive to small temperature fluctuations at these temperatures.

Nanographite/polyaniline composite films as the counter electrodes for dye-sensitized solar cells

Nanographite/polyaniline (NG/PANI) composite films were developed and characterized, and the performances of the dye-sensitized solar cells (DSSCs) employing these composite films as the counter electrode (CE) were evaluated in this study. The nanographite/aniline (NG/ANI) particle was firstly synthesized by a reflux method and served as the monomer for the electro-polymerization of the NG/PANI composite films. The surface modification of NG by ANI was confirmed by EDX mapping, TEM image, zeta-potential, and UV-Vis absorption measurements. The electro-polymerized NG/PANI composite films were characterized by Raman spectroscopy, XPS, and conducting-AFM, which verified the successful incorporation of NGs in the PANI films. The electro-catalytic activity of the NG/PANI composite film was evaluated using the positive-feedback mode of scanning electrochemical microscopy (SECM), by which a comparable heterogeneous rate constant (ks0) for the ferrocene/ferrocenium (Fc/Fc+) redox pair was obtained and compared with that of a sputtered Pt. The DSSC employing the NG/PANI (20 mC cm−2) CE exhibited a higher short-circuit current density (JSC) but lower fill factor (FF), and gave a comparable power-conversion efficiency (η) of 7.07%, as compared to that of a DSSC containing a sputtered Pt CE (η = 7.19%).

Electrochemical Synthesis of Polyaniline/Poly-O-Aminophenol Copolymers in Chloride Medium

The copolymerization ofo-aminophenol (OAP) and aniline (ANI) on Pt and ITO electrodes was studied using cyclic voltammetry in 0.1 M HCl/0.4 M NaCl solution. The films were characterized by SEM, cyclic voltammetry, and UV-Vis spectroscopy. The properties of the copolymer were compared with PANI and POAP films. The results strongly suggest that the growth of PANI-POAP films does not consist of the simple buildup of layers of homopolymers on the electrode surface as a result of OAP or ANI oxidation products in the monomer mixture, but that a new conducting polymer is formed by copolymerization.

Electrochemical preparation of poly(vinylferrocenium)perchlorate-polyaniline composite-modified platinium electrode in methylene chloride

A new surface based on poly(vinylferrocenium)perchlorate-polyaniline (PVF+ClO4–-PANI) composite-modified platinum electrode was prepared electrochemically to combine the electrocatalytic properties of an intrinsically conducting polymer and a redox polymer. The composite film was synthesized as a bilayer from individual polymerization solutions. Furthermore, PVF+ClO4– and PANI polymers were simultaneously deposited as a mixture from a methylene chloride solution containing PVF polymer and aniline monomer on Pt electrode. When PVF+ClO4– and PANI were codeposited by cycling the potential between 0.20 and 1.80 V vs Ag|AgCl, these polymers were encapsulated within each other. The encapsulation of PVF+ClO4– inside the growing PANI polymer provided the retainment of PVF+ClO4– on the electrode surface even if it was in dedoped form (PVF). This composite film was characterized by cyclic voltammetry, FTIR, SEM and conductivity measurements. The response of the composite film to catechol and hydroquinone was investigated by chronocoulometry in aqueous medium. It was found that the increase in charge consumption for catechol and hydroquinone was observed up to 7.5 and 5.0 times, respectively, when compared to that of PANI film. This might be due to the presence of PVF+ClO4– in the composite film, which played an important role in accelerating the electron transfer.

Impedance Monitoring of the Anodic Dissolution of PANi during the V2O5 Deposition Step for the PANi/V2O5 Composite Film Preparation

Vanadium pentoxide / polyaniline (V2O5/PANi) composite films were prepared by a two-step electrochemical method for the cathode material application in lithium batteries. As a first step the PANi film was potentiodynamically grown in an acid solution containing aniline monomer, and secondly vanadium oxide was oxidatively deposited on the polyaniline film in a temperature controlled VOSO4 solution. The increased anodic current efficiency in the hot VOSO4 solution results in high contents of V2O5 in the composite films. The in-situ electrochemical impedance spectra for the second step of V2O5-deposition at the PANi-film electrodes were measured. The impedance increases as the oxidative deposition of V2O5 proceeds. Polyaniline film is also oxidized during the second V2O5-deposition step in the high temperature acidic solutions, which result in the polyaniline being overoxidized to a less conductive form.

Study of polyaniline conducting/electroactive polymer as sensor for some agricultural phosphorus pesticides

Due to their wide applications as insecticides, pesticides, chemical warfare agents, etc., detection of organophosphorus compounds is of great importance. This paper deals with application of polyaniline conducting polymer (PANi) as a sensor material for detection of some agricultural organophosphorus compounds that are commonly used as insecticides and pesticides. The compounds employed in this investigation are dichlorvos, trichlorophon, and chlorpyrifos. The effects of some important parameters such as concentration, thickness of the polymer film, etc., on electrical conductivity and conductivity stability for these compounds have also been investigated. In situ electrical conductivity measurements were performed using a standard direct-current (DC) four-point probe technique. It was found that adsorption and desorption of these compounds on PANi film cause measurable change in the resistance of conducting polymers.

Electrodeposition of PANi films on platinum needle type microelectrodes. Application to the oxidation of ascorbate in human plasma

Needle type (165 μm 2) and small Pt disc (3–11 μm 2) microelectrodes were used for the electrodeposition of composite poly(aniline), PANi, films by cyclic voltammetry and chronoamperometry for the oxidation of ascorbate. PANi electroactivity at neutral pH was retained through polymer alkylation or by using large poly-anions, such as poly(vinylsulfonate), PVS, and poly(styrenesulfonate), PSS. Hence the growth of the composite films was studied in the presence of different counter ions such as SO 4 2−, Cl −, NaPVS and NaPSS. The morphology of the resulting films was examined by scanning electron microscopy. Results showed that flat PANi films with thicknesses much lower than the microelectrode radius were obtained by potentiodynamic electrodeposition. On the other hand films with mushroom shapes, with significant spill over, were obtained under constant potential. The resulting polymer modified microelectrodes films were shown to be suitable for the oxidation of ascorbate at 0.1 V vs. SCE and pH 7 with a detection limit of 1 μM for PANi/PSS composites. The current was independent of film thickness, mass transport controlled at low ascorbate concentrations and not affected by the presence of common interferences such as uric acid, glutathione or vitamin E. Due to their excellent properties the PANi–PSS film coated microelectrodes were used for the amperometric detection of ascorbate in human plasma. The results are encouraging for the use of small polymer modified Pt needle type microelectrodes for the detection of ascorbate in biological systems.