PPy Thin Film Research Articles

Flattened‐Top Domical Droplet Formed by a Poly(pyrrole) Membrane

AbstractPolypyrrole (PPy) is a promising conductive polymer (CP) with electrical versatility, easy synthesis and functionalization, stability, and biocompatibility. Diverse architectures have been adopted to improve PPy performance, but the direct and precise patterning of various architectures remains challenging. Here, the unique formation of a PPy membrane on the air/water interface of a droplet solution containing ammonium persulfate and phytic acid is investigated. When a PPy thin film forms on the air/water interface, the top of the droplet rapidly flattens. The formation procedure and final structure of the PPy thin film are visualized and quantitatively investigated. Unlike the typical globular structure of PPy, the self‐assembled PPy film surface fabricated in this study is very organized and regularly shaped. This well‐ordered membrane may have a very high buckling strength greater than the surface tension of the solution. The proposed precise fabrication method is simple and inexpensive for fabricating patterned functional membranes. These results provide new insight into the fabrication of CP and their applications in various practical electromaterial engineering fields.

Electrochemical Properties of Al Doped Polypyrrole Composite Polymer: Mott-Schottky Approximation and Density Functional Theory

Polypyrrole and Al doped polyprrole thin films were synthesized by electrochemical deposition method. FTIR spectroscopic studies confirm the formation of PPy and Al:PPy thin films. From the FESEM crosssectional images, film thickness were measured as 393.9 and 425.0 nm for the PPy and Al doped PPy thin film, respectively. Electrochemical properties of the deposited polymers are studied by Mott-Schottky analysis and electrochemical impedance spectroscopy. The calculated acceptor concentration is 5.03 × 1018 m−3 and 5.14 × 1018 m−3 for PPy and Al:PPy thin film, respectively. EIS analysis are performed to find out the effect of aluminum doping on PPy matrix. An equivalent circuit model is fitted to the EIS data to understand the behavior of coating/electrolyte interface and to determine the values of the circuit elements. Time-dependent self-consistent field and density functional theory based on CAM-B3LYP level with 6-311G(d,p) basis set are used to compute electronic properties such as HOMO and LUMO energies, ionization potential, electron affinity, electronegativity, hardness, softness. Electronic energy levels of the synthesized polymers are represented using the results of Mott-Schottky studies, and the frontier energy levels are also illustrated in this energy diagram to give more detailed explanation.

Study of optical and electrical property of NaI-doped PPy thin film with excellent photocatalytic property at visible light

Conductive polymers perform as a new class of very active photocatalysts under visible light. Among them, polypyrrole (PPy) is one of the most promising conjugated polymers with a wide range of applications. PPy and doped PPy were synthesized on glass plate in thin film form by a facile simple successive ionic layer adsorption and reaction method. Polypyrrole is doped with dodecyl benzene sulphonic acid, toluene sulphonic acid, hydrochloric acid, sodium iodide (NaI), citric acid (commercial) and citric acid (lemon). The synthesized thin film was well characterized using UV–visible spectrophotometer, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and photoluminescence (PL). The electrical conductivity was measured by Hall effect measurements. Among various organic and inorganic acid dopants, NaI-doped PPy thin film exhibited narrow band gap and has excellent ability to absorb light in red region of the spectrum. NaI-doped PPy thin film showed higher conductivity when compared to other dopants. A lower PL intensity of NaI-PPy thin film indicates higher electron–hole pair separation efficiency. The photocatalytic activities of PPy thin film and NaI-doped PPy thin film on rhodamine 6G dye under visible light were systematically investigated. NaI-doped PPy thin film had better degradation efficiency than PPy due to its higher electron–hole pair separation efficiency.

Structural, electrical and microwave properties of conducting polypyrrole thin films: effect of oxidant

This article demonstrates the synthesis of conducting polypyrrole (Ppy) thin films using different oxidants and their effect on structural, electrical and microwave properties of polypyrrole thin films. The prepared films are characterized for XRD, FTIR, SEM, Raman, DC electrical conductivity and microwave properties. The XRD analysis proves the polypyrrole films prepared using various oxidants are mostly of amorphous nature. The FTIR spectrums show that the presence of all characteristics absorption peaks of Polypyrrole. The morphological study shows massive change in SEM micrographs of polypyrrole thin films synthesized via different oxidants while the bands observed at 936 cm–1 and 971 cm–1 in the Raman spectra reveals the formation of polarons and bipolarons which confirms the conducting nature of polypyrrole thin films. The DC electrical conductivity study shows maximum electrical conductivity up to 135.8 × 10–3 S cm−1 achieved for the Ppy films synthesized using oxidant K2S2O8 also it show better microwave absorption properties in the 8–18 GHz frequency region. Similarly, Shielding effectiveness value observed for Ppy thin film prepared using oxidant K2S2O8 is relatively high which is up to 14.75 dB i.e. ∼90% microwave radiations are absorbed at 10.2 GHz.

Enhancement Supercapacitive Behavior of Electrodeposited Doped Polypyrrole for Supercapacitor Applications

Polypyrrole (PPy) have been extensively studied because of their low cost, easy production, good conductivity and controlled doping/de-doping properties as well as extensive applications in various areas such as energy storage, sensors, and electronic devices 1, 2. A detailed study of the effects of different electropolymerization conditions on the supercapacitive properties of polypyrrole (ppy) films doped using different dopants deposited on stainless steel was reported. The resulting thin films have been characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The electrochemical properties of PPy thin films were investigated by cyclic voltammetry, electorochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge. The results showed that the different electrodeposition operating conditions of synthesis and the type of dopant and the electrolyte used significantly affect the supercapacitive properties of PPy thin films. Thus, these results provide a useful orientation for the use of optimized electrodeposition modes for the growth of PPy thin films to be applied as electrode material in supercapacitors and achieved a specific capacitance of 266 F/g for amperometric deposited PPy thin film doped with 0.03 M dodecylbenzene sulfonic acid (DBSA) and using 0.1 M H2SO4 as an electrolyte. References Cai, Z.; Xiong, H.; Zhu, Z.; Huang, H.; Li, L.; Huang, Y.; Yu, X., Electrochemical synthesis of graphene/polypyrrole nanotube composites for multifunctional applications. 2017, Synthetic Metals 227, 100-105.Dubal, D. P.; Lee, S. H.; Kim, J. G.; Kim, W. B.; Lokhande, C. D., Porous polypyrrole clusters prepared by electropolymerization for a high performance supercapacitor. 2012, Journal of Materials Chemistry 22, 3044-3052. Figure 1: Cyclic voltammetry of PPy doped by DBSA and a schematic diagram of supercapacitor components Figure 1

Synergistic conductivity increase in polypyrrole/molybdenum disulfide composite

Polypyrrole/molybdenum disulfide (PPy/MoS2) composites were synthesized by in-situ chemical polymerization of pyrrole in the presence of MoS2 flakes. The conductivity of the composite with a moderate content of PPy (15–30 wt%) reached 13 S cm−1, which is markedly higher than the conductivity of both the pristine PPy and MoS2, 1 and 10−6 S cm−1, respectively. The improved conductivity was explained by the formation of ordered thin PPy films with high conductivity at the MoS2 surface. At higher pyrrole content, globular PPy was formed in the bulk of the composite resulting in an increase of a disordered polymer fraction, and the conductivity decreased. The composite conductivity is thus controlled not only by content of PPy but also by the proportions between ordered and disordered PPy phases. The structural and morphological characterization of composite materials is based on Fourier-transform infrared and Raman spectroscopies, wide-angle X-ray diffraction, and scanning and transmission electron microscopies. The charge-carrier transport in the composites fits the Mott variable-range hopping mechanism.

3D‐Printed, Superelastic Polypyrrole–Graphene Electrodes with Ultrahigh Areal Capacitance for Electrochemical Energy Storage

AbstractDisruptive custom electronics require a transformation in energy storage systems from traditional thin‐film units to shape conformable 3D components. However, current thick electrodes suffer from uncontrollable geometries and architectures, which lead to ion diffusion limitations, and poor mechanical properties. Here, designed, superelastic polypyrrole (PPy)‐coated graphene aerogel (GA) electrodes are fabricated via 3D printing and polymer self‐assembly methods. This resilient GA template (up to 90% compression) can be printed into any desired shape including engineered 3D architectures with periodic macropores, which promote the uniform deposition and adhesion of PPy onto the support. The coated PPy thin film increases the specific gravimetric capacitance of the GA electrode from 14 to 395 F g−1 with 90% retention after 5000 charging–discharging cycles. The capacitance remains the same value after 100 times compression cycles. It also improves the compressive strength by one order of magnitude from 0.14 to 2.4 MPa. Areal capacitance and energy density of the PPy–GA electrode are 2 F cm−2 and 0.78 mWh cm−2, respectively, which to the best of the knowledge break the record for compressible electrodes, respectively. This approach enables the fabrication of complex architectured energy storage modules with enhanced compressibility, ultrahigh areal electrochemical performance, and excellent cyclability.

Synthesis and characterization of polypyrrole thin film by MW-CBD method for NH3 gas sensor

The microwave-assisted chemical bath deposition method is used for synthesis of polypyrrole (Ppy) thin film. The structural, morphological, optical absorption and wettability properties of deposited Ppy thin films are studied using various characterization techniques. The X-ray diffraction pattern shows amorphous nature of Ppy thin film. To confirm the formation of Ppy compound, Fourier transform infrared spectroscopic study is used. The scanning electron microscopy study shows porous structure of Ppy thin film. The optical study revealed that Ppy thin film exhibits band gap of 3.5 eV. The Ppy film exhibited hydrophilic nature with contact angle of 41°. The Ppy films show 85% response to ammonia (NH3) gas at room temperature.

The electrochemical behavior of poly 1-pyrenemethyl methacrylate binder and its effect on the interfacial chemistry of a silicon electrode

The physico-chemical properties of poly (1-pyrenemethyl methacrylate) (PPy) are presented with respect to its use as a binder in a Si composite anode for Li-ion batteries. PPy thin-films on Si(100) wafer and Cu model electrodes are shown to exhibit superior adhesion as compared to conventional polyvinylidene difluoride (PVdF) binder. Electrochemical testing of the model bi-layer PPy/Si(100) electrodes in a standard organic carbonate electrolyte reveal higher electrolyte reduction current and an overall irreversible cathodic charge consumption during initial cycling versus the uncoated Si electrode. The PPy thin-film is also shown to impede lithiation of the underlying Si. XAS, AFM, TGA and ATR-FTIR analysis indicated that PPy binder is both chemically and electrochemically stable in the cycling potential range however significant swelling is observed due to a selective uptake of diethyl carbonate (DEC) from the electrolyte. The increased concentration of DEC and depletion of ethylene carbonate (EC) at the Si/PPy interface leads to continuous decomposition of the electrolyte and results in non-passivating behavior of the Si(100)/PPy electrode as compared to pristine silicon. Consequently, PPy binder improves the mechanical integrity of composite Si anodes but it influences mass transport at the Si(100)/PPy interface and alters electrochemical response of silicon during cycling in an adverse manner.

Layered PPy/Cr2O3 as a supercapacitor electrode with improved electrochemical performance

In the present work, we have synthesised polypyrrole (PPy), Cr2O3 and layered PPy/Cr2O3 thin films on stainless steel (SS) substrates for electrochemical supercapacitor applications. The PPy and Cr2O3 thin films were deposited by galvanostatic electrodeposition on stainless steel substrate separately. Layered PPy/Cr2O3 thin films are prepared via electrochemical polymerization of PPy on which Cr2O3 layer was deposited by electrodeposition technique. The structural and surface morphological studies of these thin films were carried out with the help of X-ray diffraction (XRD) technique and scanning electron microscopy (SEM) images. XRD study remarks that formation of crystalline Cr2O3 and amorphous PPy while in the layered PPy/Cr2O3 structure showed no additional peaks. The formation of polypyrrole in layered PPy/Cr2O3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. The SEM images showed favourable morphology for supercapacitive study. Furthermore, the electrochemical supercapacitive properties were studied by cyclic voltammetry (CV), galvanostatic charging–discharging and electrochemical impedance spectroscopy (EIS) techniques. The layered PPy/Cr2O3 thin film showed higher coulombic efficiency of 97% and specific power 49.75 kW kg−1 at current density of 0.5 mA cm−2. In addition to this, the layered PPy/Cr2O3 thin film showed higher cycling stability than that of pure PPy and Cr2O3 thin film electrodes. This may be due to outstanding electrochemical properties that are mainly attributed to the synergistic effect between PPy and Cr2O3 and its novel architecture.

Efficiently two-stage synthesis and characterization of CuSe/Polypyrrole composite thin films

A novel CuSe/PPy composite thin film was fabricated easily via electrodeposition method on ITO substrate in two stages. In order to determine deposition potentials, the electrochemical response of Cu and Se elements, and monomer were analyzed by cyclic voltammetry, and then chronoamperometry technique was used to synthesis of the conductive metal/polymer chalcogenide films. The morphology, electrical and optical properties of the films are presented in detail. SEM studies indicate that the Cu and Se nanoparticles are uniformly coated on ITO surface together with PPy. EDX analyses show that Cu and Se components are successfully electrodeposited into PPy polymer matrix. FTIR studies also confirm that PPy is synthesized and the CuSe nanoparticles are successfully loaded into PPy. The optical energy band gap (Eg) of the PPy thin films decreases from 1.78 to 1.44 eV with the addition of CuSe nanoparticles. Hall-effect measurements reveal that both films exhibit semiconducting behavior, and the addition of CuSe into the PPy matrix plays an important role in the enhancement of electrical properties. The results show that the produced CuSe/PPy nanocomposite film can be considered a promising material for solar cell applications and the two stage synthesis method used for this composite film may be applied to other metal/polymer chalcogenides due to the low-cost, large-scale and easy fabrication.

Electrochemically Controlled Ion‐exchange Property of Carbon Nanotubes/Polypyrrole Nanocomposite in Various Electrolyte Solutions

AbstractThe electrochemically controlled ion‐exchange properties of multi‐wall carbon nanotube (MWNT)/electronically conductive polypyrrole (PPy) polymer composite in the various electrolyte solutions have been investigated. The ion‐exchange behavior, rate and capacity of the electrochemically deposited polypyrrole with and without carbon nanotube (CNT) were compared and characterized using cyclic voltammetry (CV), chronoamperometry (CA), electrochemical quartz crystal microbalance (EQCM), X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It has been found that the presence of carbon nanotube backbone resulted in improvement in ion‐exchange rate, stability of polypyrrole, and higher anion loading capacity per PPy due to higher surface area, electronic conductivity, porous structure of thin film, and thinner film thickness providing shorter diffusion path. Chronoamperometric studies show that electrically switched anion exchange could be completed more than 10 times faster than pure PPy thin film. The anion selectivity of CNT/PPy film is demonstrated using X‐ray photoelectron spectroscopy (XPS).

Electrochemical Synthesis of Conducting Polypyrrole Film on Tin Substrate: Structural, Chemical and Field Emission Investigations

Electrochemical synthesis of Polypyrrole (PPy) thin films on Sn substrates has been carried out under cyclic voltammetry (CV) mode. The structural, morphological and chemical properties of the as-synthesized PPy films were investigated using various characterization techniques like SEM, UV-Visible and FTIR. Furthermore, field emission (FE) behaviour of the PPy thin film emitter were carried out at base pressure of ~ 1×10-8 mbar and found to be interesting. The threshold field, required to draw emission current density of 1 μA/cm2, is observed to be 0.90 V/μm and very high emission current density of 12.87 mA/cm2 has been drawn at applied field of ~ 2.8 V/μm. The emission current stability investigated at preset values of 1, 10 and 100 μA/cm2 is observed to be fairly good over duration of more than three hours. The simplicity of the synthesis route coupled with the capability to deliver very high emission current density at relatively lower applied field make the PPy thin field emitter as a potential candidate for practical applications in field emission based devices

In Situ Polymerization and Characterization of Highly Conducting Polypyrrole Fish Scales for High-Frequency Applications

Polypyrrole (Ppy) thin films on alumina were synthesized by an in situ chemical oxidative polymerization method at 300 K with equal monomer-to-oxidant ratio. Fourier transform infrared spectroscopy (FTIR) and FT-Raman spectroscopy confirmed the formation of Ppy. A thickness-dependent change from cauliflower to fish-scale morphology was observed. Microwave properties such as transmission, reflection, shielding effectiveness, permittivity, and microwave conductivity are reported in the frequency range from 8 GHz to 12 GHz. The direct-current (DC) conductivity varied from 9.45 × 10−3 S/cm to 17.29 × 10−3 S/cm, whereas the microwave conductivity varied from 63.07 S/cm to 349.08 S/cm. The shielding effectiveness varied between 6.18 dB and 10.39 dB.

Development of polypyrrole coated copper nanowires for gas sensor application

Both polypyrrole (PPy) and polypyrrole coated copper thin films were synthesized successfully via two-step methods. PPy nanorods films were first grown chemically, and then PPy thin films were fabricated on glass substrates using dip-coating technique. The resulting films were examined via various characterization methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Thermal Gravimetric Analysis (TGA). Gas sensor devices were fabricated and the gas sensitivity for (PPy) coated copper was measured as a function of temperature for both O2 and CO2 gases. The maximum sensitivity for O2 gas was around 160% and the maximum sensitivity for CO2 was 300%.

Effect of anionic dopants on thickness, morphology and electrical properties of polypyrrole ultra-thin films prepared by in situ chemical polymerization

Abstract The effect of different dopant anions on deposition and characteristics of polypyrrole (PPy) thin film has been studied in this work. Ultra-thin films of conducting PPy were deposited on insulating surfaces of glass and oxidized silicon wafer by in situ chemical polymerization in the presence of different anionic dopants including sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, α-naphthalene sulfonic acid, anthraquinone-2-sulfonic acid sodium salt monohydrate/5-sulfosalicylic acid dehydrate, and camphor sulfonic acid. Hydrophilic/hydrophobic properties and morphology of the self-assembled monolayer of N-(3-trimethoxysilylpropyl)pyrrole, the surface modifying agent in this work, and PPy thin films were characterized before and after deposition by contact angle measurements, field emission scanning electron microscopy, and atomic force microscopy. Chemical structure, thickness, and conductivity of the thin films were also studied by attenuated total reflectance Fourier transform infrared spectrometer, ellipsometry, and four-point probe measurements. The results showed deposition of thin films of conducting PPy with comparable thickness in the range of 6–31 nm and different morphologies, uniformity, and smoothness with average roughness in the range of 0.3–6 nm and relatively high range of conductivity on the modified surfaces.

Polypyrrole nanostructures and their field emission investigations

Polypyrrole (PPy) nanostructures have been synthesized on indium doped tin oxide (ITO) substrates by a facile electrochemical route employing cyclic voltammetry (CV) mode. The morphology of the PPy thin films was observed to be influenced by the monomer concentration. Furthermore, FTIR revealed formation of electrically conducting state of PPy. Field emission investigations of the PPy nanostructures were carried out at base pressure of 1×10-8 mbar . The values of turn-on field, corresponding to emission current density of 1 μA/cm2 were observed to be 0.6, 1.0 and 1.2 V/μm for the PPy films characterized with rod-like, cauliflower and granular morphology, respectively. In case of PPy nanorods maximum current density of 1.2 mA/cm2 has been drawn at electric field of 1 V/μm. The low turn on field, extraction of very high emission current density at relatively lower applied field and good emission stability propose the PPy nanorods as a promising material for field emission based devices.

Sensitive detection of ammonia by reduced graphene oxide/polypyrrole nanocomposites

The polypyrrole (PPy) and its composite with reduced graphene oxide (rGO) are prepared by drop cast in-situ oxidative polymerization method. The fabricated thin film sensors are used for ammonia (NH3) gas sensing and are characterized by TEM, FEG-SEM, FT-IR, X-Ray diffraction and UV–vis methods. The PPy/rGO thin film sensors show very good sensing response to ammonia gas and are able to sense ammonia at 3ppm. Sensitivity of these composites increases with increasing concentration of ammonia gas, and starts saturating at higher concentration. Sensitivity of PPy/rGO based sensor is nearly 3 times more than the PPy thin film sensor. It has been found that the sensors recovered fully after heating up to ∼50°C.

Polypyrrole thin films decorated with copper nanostructures as counter electrode for dye-sensitized solar cells

A two-step electrochemical polymerization method for the fabrication of polypyrrole (PPY) thin films decorated with copper nanostructures on a stainless steel has been employed. The PPY film thickness affects the size, shape, and the number density of the copper nanostructures and provides an easy approach to control the morphology of these nanostructures. SEM images show nanorod like structures of copper on 200 nm PPY film. By employing this composite film as counter electrode (CE), a dye-sensitized solar cell (DSSC) achieves a conversion efficiency of 7.42%, which is greater than Pt CE based DSSC (5.63%). The superior photovoltaic efficiency for the Cu-PPY film is attributed to unique porous PPY thin film and copper nanorods structure that leads to higher cathodic current density (5.38 mA/cm2), large electrocatalytic activity, and small charge transfer resistance(1.92 Ω cm−2). Therefore, Cu-PPY composite can be considered a competitive and promising CE material with the traditional and expensive Pt CE, for large-scale DSSCs production.

Polypyrrole-coated LiCoO2 nanocomposite with enhanced electrochemical properties at high voltage for lithium-ion batteries

A conducting polypyrrole thin film is successfully coated onto the surface of LiCoO2 by a simple chemical polymerization method. The structure and morphology of pristine LiCoO2 and PPy-coated LiCoO2 are investigated by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Energy dispersive X-ray spectroscopy (EDXS), Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA) further demonstrate the existence of PPy. The electrochemical properties of the composites are investigated by galvanostatic charge–discharge test and AC impedance measurements, which show that the conductive PPy film on the surface significantly decrease the charge-transfer resistance of LiCoO2. The PPy-coated LiCoO2 exhibits a good electrochemical performance, showing initial discharge capacity of 182 mAh g−1 and retains 94.3% after 170 cycles. However, the retention of pristine LiCoO2 is only 83.5%. The rate capability results show that the reversible capacity retention (10C/0.2C) of LiCoO2 increases from 52.4% to 80.1% after being coated with PPy. The continuously coated thin PPy film is just like a capsule shell, which can protect the core (LiCoO2) from corrosion causing by the HF attacking and greatly reduce the dissolution of Co into electrolyte.