Polypyrrole Thin Films Research Articles

Mapping the nanoscale elastic property modulations of polypyrrole thin films in liquid electrolyte with EC-AFM.

Linking structure to mechanical and elastic properties is a major concern for the development of novel electroactive materials. This work reports on the potential-induced changes in thickness and Young modulus of a substrate supported, perchlorate doped polypyrrole thin film (<100 nm) investigated with electrochemical atomic force microscopy (AFM) under in situ conditions. This was accomplished by nanomechanical mapping of potentiodynamically electropolymerized polypyrrole film in electrolyte solution with AFM during redox cycling. The polypyrrole film thickness and Young modulus follow the electrical potential nearly linearly, increasing due to solvent and ion influx as the film is oxidized, and decreasing during reduction. Our measurements also confirm the presence of a potential-independent, passive swelling which is accompanied by softening of the film, likely caused by osmotic effects. Additionally, the heterogeneous distribution of the Young modulus can be directly traced to the typical nodular surface topography of polypyrrole, with the top of the nodular area possessing lower modulus, thus highlighting the complex relationship between topography and elastic properties.

Fast pulsed electrodeposition of silver nanoparticles on polypyrrole thin films for antibacterial and biomedical applications

This research paper presents a fast method for the double pulse electrodeposition of silver nanoparticles on a thin polypyrrole film with a thickness of about 4 µm, aiming to improve its electrical conductivity and antibacterial activity for biomedical applications. The electrodeposition and the electrochemical behavior of the deposits was studied using chronoamperometry and electrochemical impedance spectroscopy. SEM and XRD were used to characterize the morphological and microstructural characteristics of the deposits. The antibacterial performances of the deposits were tested against E.coli and S.aureus bacteria. It was found that the AgNO3 concentration of 10−2 M and/or the duration of the two pulses (1 s and 10 s) led to the deposition of micrometric or submicrometric Ag particles inhomogeneous in size and distribution on the PPy surface. The lower AgNO3 concentration (10−3 M) and the shorter pulse durations (0.1 s and 1 s) resulted in nanometric Ag particles with the most homogeneous size and distribution on the PPy surface. Furthermore, the Ag nanoparticles on PPy surface showed the highest electrical conductivity and the strongest killing efficiency of the two types of bacteria (100% against E.coli and 99.99% against S.aureus).

Effect The Finalizations Multi Wall Carbon Nanotube on The Characteristics of Polypyrrole Thin Films

The nanocomposite (PPy/fMWCNT) is prepared via electrochemical polymerization onto indium tin oxide (ITO) coated glass for pyrrole (Py) monomer with oxalic acid (C2H2O4) and various concentration from functionalized multi wall carbon nanotube fMWCNT (0.01, 0.02) in the 130 mL from distilled water. The structure, morphology and optical properties of thin films were investigated via X-Ray diffraction (XRD), Filed Emission Scanning Electron microscopy (FE-SEM), ultraviolet-visible (UV-VIS) spectroscopy and Fourier Transform Infrared (FT-IR) Spectroscopy. The X-ray diffraction pattern indicates that the prepared thin films are of polycrystalline structure at 2θ= (25, 42)o. The band gap of thin films decreases from 2.4 to 2.09 eV as the fMWCNT increased from 0.01 to 0.02 M, whereas FTIR showing the distinctive bonds of these films

Conductive Polymer Coated Layered Double Hydroxide as a Novel Sulfur Reservoir for Flexible Lithium-Sulfur Batteries.

Lithium-sulfur battery (LSB) is widely regarded as the most promising next-generation energy storage system owing to its high theoretical capacity and low cost. However, the practical application of LSBs is mainly hampered by the low electronic conductivity of the sulfur cathode and the notorious "shuttle effect", which lead to high voltage polarization, severe over-charge behavior, and rapid capacity decay. To address these issues, a novel sulfur reservoir is synthesized by coating polypyrrole (PPy) thin film on hollow layered double hydroxide (LDH) (PPy@LDH). After compositing with sulfur, such PPy@LDH-S cathode shows a multi-functional effect to reserve lithium polysulfides (LiPSs). In addition, the unique architecture provides sufficient inner space to encapsulate the volume expansion and enhances the reaction kinetics of sulfur-based redox chemistry. Theoretical calculations have illustrated that the PPy@LDH has shown stronger chemical adsorption capability for LiPSs than those of porous carbon and LDH, preventing the shuttling of LiPSs and enhancing the nucleation affinity of liquid-solid conversion. As a result, the PPy@LDH-S electrode delivers a stable cycling performance and a superior rate capability. Flexible battery has demonstrated this PPy@LDH-S electrode can work properly with treatments of bending, folding, and even twisting, paving the way for wearable devices and flexible electronics.

Facile synthesis of nanogranular PPy thin films for sensitive and selective detection of toxic NO gas

The pyrrole monomers have been synthesized by in situ oxidative polymerization and followed by the drop casting of polypyrrole thin films onto glass. The optimized PPy thin film for gas sensor showed the highest NO 2 sensitivity of 40.08 % at room temperature with a stable response even after 45 days with a retention of stability of around 86 %. The gas sensing results suggested that the nanogranular PPy sensor exhibited an excellent response toward NO 2 and also showed high sensitivity even at low concentrations up to 10 ppm. • Synthesis of pyrrole monomers by in situ oxidative polymerization for NO 2 gas sensor. • Achieve sensitivity of 40.08 % at room temperature with a stable response even after 45 days. • Selective sensing towards NO 2 within a wide range of concentrations from 10 to 100 ppm. • The sensor exhibits reliable long-term stability, reproducibility and reversibility. Nanogranular polypyrrole (PPy) have been synthesized by in-situ oxidative polymerization of pyrrole monomer followed by deposition of PPy thin films onto a glass substrate by drop casting method. The deposited thin films were characterized for their structural, morphological, compositional studies using x-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and x-ray photoelectron spectroscopic (XPS) studies. The XRD patterns revealed that the synthesized films are amorphous in nature. FE-SEM microscopic images exhibit agglomerated granular-like morphology of PPy thin films with high degree of roughness. The XRD patterns confirm the amorphous nature of PPy thin films. XPS analysis reveals the formation of PPy. The gas sensing properties of PPy thin film based gas sensor were studied in terms of sensitivity, response-recovery time, selectivity and stability by varying the concentration of nitrogen dioxide (NO 2 ) gas. The optimized PPy thin film gas sensor showed highest sensitivity of 40.08 % at room temperature with stable response even after 45 days with retention of stability around 86%. The gas sensing results suggested that nanogranular PPy sensor exhibited an excellent response toward NO 2 and also showed high sensitivity even at low concentrations upto 10 ppm level.

Anticorrosive Polymeric Coatings

Abstract In order to improve the anticorrosion protection properties, polypyrrole thin films were deposited on silicon steel plates. The anticorrosive protection effect of the polypriol coating was evaluated by electrochemical measurements in two different aqueous solutions of potassium chloride and hydrochloric acid. Polypyrrole-coated silicon steel plates were immersed for one and seven days, respectively. The obtained results show that the thin layer of polypyrrole ensures effective protection of silicon steel against corrosion, especially in aqueous potassium chloride solution.

Exploitation of SnO2/Polypyrrole Interface for Detection of Ammonia Vapors Using Conductometric and Optical Techniques: A Theoretical and Experimental Analysis.

This study describes the construction of a lab-built Surface Plasmon Resonance (SPR) system for gas sensing applications employing a highly sensitive and trustworthy optical approach. The nanocomposite thin film of tin oxide (SnO2) and Polypyrrole (PPy) were prepared for sensing highly toxic gas, i.e., ammonia (NH3) gas. The gas sensor was validated by both optical and conductometric techniques of gas sensing. The optical SPR gas sensor is based on the change in refractive index at the SnO2/Polypyrrole (PPy) interface with gas adsorption (NH3). The thickness of SnO2 and Polypyrrole thin films was optimised using theoretical calculations for a sharp SPR reflectance curve. The manuscript also offers theoretical SPR curves for different PPy and SnO2 layer thicknesses. To support the theoretical conclusions, the effects of NH3 gas on the prism/Au/SnO2/Polypyrrole system were also investigated experimentally. In comparison to other research described in the literature, it was observed that the constructed sensor’s sensitivity was higher. The obtained results demonstrate the utility of the SPR setup in the investigation of the interactions of adhered gas molecules with dielectrics and gas sensing. For conductometric gas sensing studies, the film having optimised thicknesses for sharp SPR reflectance curves was separately prepared on Interdigitated Electrodes. At a low working temperature of roughly 150 °C, the sensing response of the constructed film was observed and found to be maximal (60).

Effect of Substrate Temperature on Porosity and Gas Sensing Properties of SnO2-B: Doped Polypyrrole Thin Films

Porous SnO2-B: doped polypyrrole thin films were synthesized by the dissolving 0.15M of stannous chloride (SnCl4.5H2O) (10%, 20%, 30%, 40%, and 50%) in 25ml of ethanol and adding 4% of Boric acid (H3BO3) and polypyrrole (1:1) using chemical spray pyrolysis technique. Studies on effect of substrate temperature on porosity of the deposited films were at four different temperatures ranging 200⁰C to 280⁰C. The H2S gas was used to study the gas sensing behavior of deposited films and all films were characterized by using IR, XRD, SEM, UV-Vis spectrometry, and current-voltage measurement.

EXPERIMENTAL STUDY: THE ELECTRICAL CONDUCTIVITY OF POLYPYRROLE DOPED ORGANIC ACIDS THIN FILM

Properties of materials in microscale are different from those in bulk form. This article aims to presents the experimental studies of the electrical properties of Polypyrrole thin film doped in organic acid. Ten samples of Polypyrrole doped in organic acids thin films with different layers were prepared using the spin coating method applied on glass substrates. The electrical resistance of the thin film is measured as a function of film thickness and temperature.

Super-capacitive behaviour of polypyrrole thin film prepared by electrodeposition technique and characterization

The study conducted in this paper is on fabrication of thin poly-pyrrole film designed with an electro-deposition method on AISI304 stainless steel substrate. For enhancing super-capacitive characteristics of electrodes, a thin poly-pyrrole layer was deposited with an electro-deposition technique, following a potentiostatic method from an aqueous solution of pyrrole containing 5-sulfosalicylic dehydrated acid (SSA). The effects of thickness were also studied on the electro-chemical properties of samples on 10 min, 15 min, 20 min, 25 min and 30 min. The optimal performance while using supercapacitor was tested on room temperature with 30.72 F g−1 specific capacitance at 5mVs−1 at 25 min. SEM was used to characterise the surface morphology for 10 min, 15 min, 20 min, 25 min and 30 min. Electrochemical properties were studied with Cyclic Voltammogram from which a maximum specific capacitance value was calculated to be 30.72 F g−1 on 25 min. In this research, super capacitive behaviour was also studied using the electrochemical impedance spectroscopy and galvanostatic discharging-charging technique.

Stability enhancement of polypyrrole thin film ammonia sensor by camphor sulfonic acid dopant

Stability enhancement of polypyrrole thin film ammonia sensor by camphor sulfonic acid dopant

Effects of Interchain Crosslinking By Alkyl Dihalides on the Ion Insertion Mechanism of Polypyrrole Thin Films

Conductive polymers (CPs) such as polypyrrole (PPY) and PEDOT can exhibit high charge storage capacities, high electronic conductivities, and tunable chemical and optical properties. CPs thus have a wide range of applications in electronic devices, including in organic electronics, sensors, and battery materials. The electrochemical properties of PPY in particular can be controlled to provide high electronic conductivity (up to 200 S/cm) and high redox activity (up to 500 F/g), making it an attractive material for device application. The electrochemical characteristics of PPY are commonly controlled by adjusting polymerization conditions, adding dopants, and forming composites with other polymers. A lesser studied phenomenon is the effect of nitrogen substituents on the electrochemical properties of PPY. In this work, we present an investigation into the charge-transfer mechanisms and electrochemical properties of nanoscale PPY films before and after interchain crosslinking with several different alkyl dihalides. Our investigation involves deposition and alkylation of PPY thin films followed with optical and electrochemical characterization via electrochemical quartz crystal microbalance and spectroscopic ellipsometry. Individual polymer chains in the PPY film are connected across adjacent nitrogens via an alkyl bridge, and the properties of the subsequent films are examined and compared to those of intrinsic PPY and other redox active materials. The results of our ongoing research give insight into new sub-classes of CPs with different redox properties and ion transfer mechanisms from intrinsic PPY. These novel PPY derivatives are low-cost, easy to synthesize, and show promise for application to sensors, ion exchange materials, and charge-storage devices.

Extension of the potential intervals of high redox activity and electronic conductivity of polypyrrole films on electrode surface via their electrochemical multi-cycle treatment in monomer-free solution

Thin polypyrrole films (thickness: about 30 nm) have been deposited at electrode surface via potentiostatic oxidation of dilute (1 mM) pyrrole solution in acetonitrile (AN). It has been shown that their subsequent treatment by means of multi-cycle voltammetry within a broad potential range (up to -2.0 V vs. Ag/Ag+ in AN) leads to their "activation", i.e. to a very strong extension of their redox response region in the negative direction as well as to almost uniform distribution of the redox activity within this potential range. Region of their high conductivity under in situ conditions has also extended significantly. Spectral and electrocatalytic properties of such PPy films before and after their "activation" have been analyzed. Two parameters for characterization of the variation of film's properties in the course of its "activation" (redox efficiency of polymerization and width of electroactivity region) have been proposed. Comparison of films deposited at different potentials (from 0.6 V to 0.8 V) has revealed that the effect of their "activation" increases for lower polymerization potential. Films deposited at 0.6 V possess after their "activation" a very broad electroactivity range (almost 2.5 V) and a record high redox charge per monomer unit (its oxidation degree) inside the film in contact with AN solution, 0.45. Such unusual properties of "activated" PPy films make them prospective materials for various applications.

Effect of Electrosynthesis Potential on Nucleation, Growth, Adhesion, and Electronic Properties of Polypyrrole Thin Films on Fluorine-Doped Tin Oxide (FTO).

Polypyrrole (PPy) is one of the most attractive conducting polymers for thin film applications due to its good electrical conductivity, stability, optical properties, and biocompatibility. Among the technologies in which PPy has gained prominence are optoelectronics and solar energy conversion, where transparent electrodes such as fluorine-doped tin oxide (FTO) or indium tin oxide (ITO) are frequently used. However, FTO substrates have the notable advantage that their components are widely available in nature, unlike those of ITO. Recognizing the importance that the FTO/polypyrrole system has gained in various applications, here, we studied for the first time the nucleation and growth mechanism of electro-synthesized PPy on FTO. Additionally, the effect of the synthesis potential (0.9, 1.0, 1.1, and 1.2 V vs. Ag/AgCl) on the homogeneity, adhesion, conductivity, and HOMO energy levels of PPy films was determined. From current–time transients and scanning electron microscopy, it was found that films synthesized at 0.9 and 1.0 V exhibit 3D growth with progressive nucleation (as well as lower homogeneity and higher adhesion to FTO). In contrast, films synthesized at 1.1 and 1.2 V follow 2D growth with instantaneous nucleation. It was also evident that increasing the polymerization potential leads to polymers with lower conductivity and more negative HOMO levels (versus vacuum). These findings are relevant to encourage the use of electro-synthesized PPy in thin film applications that require a high control of material properties.

Reversible Switching of Battery Internal Resistance Using Iongate Separators

AbstractBattery separators are a critical component that greatly determine cell calendar life and safety. Generally, these separators are passive with no ability to reversibly change their properties in order to optimize battery performance. Here, an iongate separator is demonstrated, which allows ion transport while in the oxidized “on” state but limits ion transport when switched to the reduced “off” state. This is achieved by depositing a dense 300 nm thin film of polypyrrole:polydopamine (PPy:PDA) on a conventional polyolefin separator. By using this iongate separator as a third electrode, a rapid and reversible order of magnitude increase of iongate resistance is achievable. The iongate battery shows similar cycling performance to a normal battery while in the “on” state, but cycling can be reversibly shut‐off when the iongate separator is reduced to the “off” state. During elevated temperature storage with the iongate separator in the “off” state, battery capacity loss is decreased by 37% and transition metal crossover is greatly suppressed when compared to a normal battery without the iongate. Additionally, rapid shut‐off during discharge is demonstrated by directly shorting the iongate separator to the anode.

Plasma Functionalized Scaffolds of Polyhydroxybutyrate Electrospun Fibers for Pancreatic Beta Cell Cultures

Fibrous scaffolds based on biodegradable and biocompatible polyhydroxybutyrate (PHB) were produced by electrospinning. The scaffolds were coated by a thin solid film of polypyrrole, PPyI, deposited by plasma polymerization technique. FTIR and Raman spectroscopy results confirm the presence of PPyI on the PHB fibers, in FTIR can be show the signal of the NH2 groups characteristic of the polypyrrole, so Raman show a broad band due to fluorescence from the PPyI coating. The morphology of the scaffolds was characterized by scanning electron microscopy, and the average fiber diameter of PHB is (2.68 ± 1.69) μm, also the average fibers diameter of PHB-PPyI is (3.57 ± 1.36) μm, the comparation of the average fibers diameter of coated and uncoated indicates that the average PPyI coated thickness is 0.45 μm. Crystallinity of the PHB fibers was characterized by X-ray diffraction and differential scanning calorimetry, the degree of crystallinity is estimated at 70%. Pancreatic beta cells (from the RIN-M cell line) were cultured on PHB and PHB-PPyI scaffolds. Cell viability results showed that the surface modified material is a good cell culture substrate for beta cells.

Construction of a High-Performance Three-Dimensional Structured NiCo2O4@PPy Nanosheet Array Free-Standing Electrode for a Hybrid Supercapacitor

Asymmetric supercapacitors (ASCs) with free-standing electrodes have attracted extensive attention due to enhanced power density, high energy density, long-term stability, and low inner resistance. Herein, a three-dimensional (3D) hierarchical nanosheet array electrode (CC@NiCo2O4@PPy), consisting of a polypyrrole (PPy) thin film shell and spinel NiCo2O4 as the core, was prepared on carbon cloth (CC) via a simple two-step electrodeposition. Since the protection of the highly conductive pseudocapacitive PPy shell, the integrated electrode delivers an enhanced specific capacitance (1687.2 F g–1 or 257.8 mAh g–1 at 1 A g–1) and a high cycling stability (91.9% capacitance retention after 10,000 cycles at 10 A g–1). We further demonstrate the ASC based on CC@NiCo2O4@PPy/6 M KOH/active carbon, which can be cycled over 10,000 times with 80% retention at 4 A g–1. Moreover, the prepared ASCs present a favorable rate capability with high energy densities of 46.5 and 31 Wh kg–1 at power densities of 725 and 7246 W kg–1, respectively. Our work provides a viable approach to construct a hierarchical 3D structure under ambient conditions and opens possibilities for adopting it in hybrid supercapacitors.

Photoelectrochemical Stability under Anodic and Cathodic Conditions of Meso-Tetra-(4-Sulfonatophenyl)-Porphyrinato Cobalt (II) Immobilized in Polypyrrole Thin Films.

Cobalt porphyrins have emerged as promising catalysts for electrochemical and photoelectrochemical applications because of their good performance, low cost and the abundance of cobalt in the earth. Herein, a negatively charged porphyrin meso-tetra-(4-sulfonatophenyl)-porphin (TPPS) was immobilized in polypyrrole (PPy) during the electro-polymerization, and then it was metallized with cobalt to obtain meso-tetra-(4-sulfonatophenyl)-porphyrinato cobalt (II) (CoTPPS) as a dopant in PPy. The coatings were evaluated as photoelectrodes towards thiosulfate oxidation and oxygen reduction. For comparison purposes, the photoelectrochemical behavior of ClO4−-doped polypyrrole films was also evaluated. Characterizations by chronoamperometry, UV-Vis spectroscopy and Raman spectroscopy showed that polypyrrole is stable under anodic and cathodic conditions, but CoTPPS and TPPS immobilized in PPy are degraded during the anodic process. Thus, decreases in photocurrent of up to 87% and 97% for CoTPPS-doped PPy and TPPS-doped PPy were observed after a 30-min chronoamperometry test. On the other hand, good stability of CoTPPS and TPPS immobilized in PPy was observed during photoelectrochemical oxygen reduction, which was reflected in almost constant photocurrents obtained by chronoamperometry. These findings are relevant to understanding the role of CoTPPS as a catalyst or pre-catalyst in photoelectrochemical applications such as water splitting. In addition, these results could pave the way for further research to include CoTPPS-doped PPy in the design of novel photocathodes.

Plasma treatment toward electrically conductive and superhydrophobic cotton fibers by in situ preparation of polypyrrole and silver nanoparticles

Smart fibers with multifunctional properties, such as antimicrobial activity, electrically conductive, ultraviolet protection, and superhydrophobic properties have been highly desirable. In this study, a nanocomposite composed of polypyrrole (Ppyr) and silver nanoparticles (AgNPs) were synthesized and immobilized into plasma-activated cotton utilizing pad dry cure finishing process of pyrrole and silver nitrate (AgNO3) into cotton fibers to establish a persistent multifunctional surface. An oxidation-reduction polymerization of pyrrole into polypyrrole associated with reduction of Ag+ ions into Ag0 nanoparticles leads to their permanent insolubility in the internal fibrous matrix to result in high fastness without changing the mechanical characteristics of the treated fabrics. The electrically conductive cotton smart fabric was fabricated by plasma-assisted immobilization of the polypyrrole conductive polymer in the presence and absence of AgNPs. Nano-structural thin film of polypyrrole and silver nanoparticles was developed in situ after plasma treatment of cotton fibers. The superhydrophobic character was imparted to the cotton fibers by treatment with hexadecyltrimethoxysilane (HDTMS). The morphologies and chemical composition were investigated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Both air-permeability and stiffness of the treated cotton fabrics were explored to evaluate their comfort properties. The antibacterial performance against E. coli and S. aureus were explored. In addition, the treated fabrics exhibited a high protection against ultraviolet light.

Solvent-assisted dispersive liquid-solid phase extraction of organophosphorus pesticides using a polypyrrole thin film-coated porous composite magnetic sorbent prior to their determination with GC-MS/MS.

A porous composite magnetic sorbent was developed and used as a solid phase for the solvent-assisted preconcentration of organophosphorus pesticides. The hierarchical porous composite sorbent was composed of polypyrrole thin film coated on the surface of porous alginate beads with embedded magnetite nanoparticles. The pores in the alginate hydrogel beads were produced by carbon dioxide bubbles from the reaction of incorporated calcium carbonate with hydrochloric acid. The porous network was filled with dichloromethane to assist extraction. The fabricated porous composite sorbent was characterized and sorbent fabrication and extraction conditions were optimized to obtain the best extraction performance. The developed sorbent was coupled with GC-MS/MS to determine organophosphorus pesticides in fruit juices and vegetable. Underoptimized condition, the developed method provided good linear range of 0.03-200μgL-1 for dichlorvos, malathion, and fenthion, and 0.075-200μgL-1 for mevinphos, dimethoate, and parathion methyl, respectively. Limits of detection were in the range 0.010 to 0.025μgL-1. This method exhibited good relative recoveries in the range 84 to 99% and RSDs lower than 8%. The good stability of the sorbent enabled up to eight cycles of reuse.Graphical abstract.