PPy Film Research Articles

Electrodeposited PPy@TiO2 and PEDOT@TiO2 Counter Electrodes for [Co(bpy)3]2+/3+ Redox Mediator-Based Dye-Sensitized Solar Cells

The main goal of this work is to enhance the catalytic performance of PPy and PEDOT films toward the Co2+/Co3+ redox couple. PPy and PEDOT films were electrodeposited separately on a porous TiO2 template to assess their suitability as alternative catalysts in dye-sensitized solar cells (DSSC) based on the [Co(bpy)3]2+/3+ redox shuttle. The obtained PPy@TiO2 and PEDOT@TiO2 counter electrodes displayed much rougher surfaces. Electrochemical studies indicate the superior catalytic activity of both the electrodeposited electrodes toward Co3+ reduction, as indicated by lower charge transfer resistance than that of pristine films and even that of Pt electrodes. Therefore, the fabricated DSSC devices with these counter electrodes achieved higher power conversion efficiencies compared to cells with pristine PPy and PEDOT counter electrodes, or even with a Pt counter electrode. Interestingly, the assembled DSSC device with a PEDOT@TiO2 counter electrode displayed the highest performance among all with a power conversion efficiency of 6.62%, which is better than that obtained by the device with a Pt electrode (6.07%).

Effect of Graphene Oxide and Temperature on Electrochemical Polymerization of Pyrrole and Its Stability Performance in a Novel Eutectic Solvent (Choline Chloride-Phenol) for Supercapacitor Applications.

Polypyrrole (Ppy)-modified graphene oxide (GO) electrodes were synthesized for the first time in a choline chloride–phenol-based deep eutectic solvent at various temperatures via electrochemical methods without the addition of any inorganic or organic catalysts. The surface morphologies and structures of the modified films were assessed via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The electrochemical properties and stability of the modified electrodes were investigated via cyclic voltammetry and impedance spectroscopy at various temperatures and scan rates. The results showed that the specific capacitance of the nanocomposites decreased with increasing scan rate during cycling. Additionally, the specific capacitances of the pure Ppy and Ppy/GO films increased with increasing temperature of the electrolyte (monomer-free), attributed to the reduction in viscosity at elevated temperature. The specific capacitances at 5 mV s–1 were found to be 1071.78 and 594.79 F g–1 for Ppy/GO (20 wt %) at 50 and 25 °C, respectively. It was also observed that the resistance in the cell decreased with increasing electrolyte temperature. Ppy/GO at 50 mV s–1 was found to have the highest capacitance retention of 85% after 2000 cycles, showing better cycling stability than the pure Ppy film. Herein, the incorporation of GO in the Ppy matrix led to improved specific capacitance and cyclic stability, suggesting that Ppy/GO could represent a promising electrode material for supercapacitor applications.

Structural and Magnetic Properties of Electrodeposited Cobalt-Polypyrrole Composite Films

Co particles were electrodeposited at an electrode potential of -2.0 V on ITO/PPy (500 nm) substrates. During Co electrodeposition, charge density was changed from 400 to 5000 mC cm-2 in order to control the Co amount. Current density-time transients showed that the dominant reaction is PPy undoping for the initial times and Co deposition for the later times. Structural characterization was done by a Fourier transformed infrared (FTIR) spectrometer and a scanning electron microscope (SEM). FTIR spectra of the Co-PPy composite films have similar to that of the PPy film but peak intensities decrease as the charge density increases due to the surface covering by Co (by SEM). The chemical composition was detected by an energy dispersive spectrometer. For all films, C and N (belonging to PPy layer), O (due to oxidized character of PPy layer), F (doping anion) and Co peaks were obtained. Magnetic properties were measured by a vibrating sample magnetometer. Some films with Co charge density of 600, 700, 4000 and 5000 mC cm-2 have nearly isotropic magnetic behavior and the others are anisotropic. The isotropic behavior may arise from the very weak texture and preferred orientation of the films.

In-situ measurement of drying and electrochemical-cycling-induced mechanical behavior and delamination of polypyrrole electrodes for energy storage applications

Delamination during the fabrication and operation of thick electrodes is one of the major instabilities that prevent their utility for high energy density electrochemical devices. In this study, we investigate the deformation and delamination of polypyrrole (pPy) film electrodes using in-situ measurements of curvature/stress. At the beginning of drying process, the water in the film exited continuously, while the film did not deform accordingly. Then, the film rapidly contracted near the end of the evaporation process and remained in its equilibrium contracted state. The film deformation was found to be caused by the evaporation of moisture near the polymer chain, whereas it was not affected by the evaporation of free water in the pores, causing the mismatch between the deformation and evaporation. Importantly, film delamination was identified in real time as the rapid stress drop corresponded to the peeling of the film from the substrate. The interfacial fracture energy was quantified to estimate the adhesion strength of the interface with various treatments. Moreover, electrochemical-cycling-induced delamination was successfully identified based on the type of delamination. We believe this study would be beneficial for both the development and operation of thick electrodes with high energy density and stability.

A tattoo-inspired electrosynthesized polypyrrole film: crossing the line toward a highly adherent film for biomedical implant applications

Polypyrrole (PPy) films have demonstrated promising application for implants due to their unique topographical and electronic properties. However, the limited PPy adhesiveness to metallic surfaces remains a challenge. Consequently, we propose a two-step technique for the surface modification of titanium (Ti) via a plasma electrolytic oxidation (PEO) step to serve as mechanical interlocking for the subsequent deposition of a highly adherent PPy film (PEO + PPy). Ti discs with machined and PEO-modified surfaces were used as controls. For the experimental groups, PPy film was deposited onto such surfaces by electrodeposition. Then, the role of machined and PEO surfaces in the synthesis, conductivity, microstructure, mechanical, electrochemical, microbiological, and biological properties of the PPy film was investigated. The results showed that a highly adherent “tattoo-inspired” PPy thin film was successfully achieved when the Ti surface was pretreated via PEO. PEO + PPy enhanced Ti mechanical and tribological properties by inducing a lower friction coefficient and wear loss due to the cushion effect of PPy film, besides promoting higher corrosion resistance. The “cauliflower-like” morphology of the PPy favored protein adsorption, calcium phosphate growth and demonstrated cell biocompatibility. The association between PEO and PPy film can be considered bioactive and is promising for the triggering of superior long-term stability of biomedical implants.

Rapid and simple preparation of an MXene/polypyrrole-based bacteria imprinted sensor for ultrasensitive Salmonella detection

• Electrochemical fabrication of MXene-doped PPy film. • The MXene/PPy-based bacteria imprinted sensor was simple and rapid developed. • Label-free and ultrasensitive detection of Salmonella with a LOD of 23 CFU/mL. • The MPBIP sensor exhibited high selectivity and good practicality. Efficient and rapid detection of Salmonella is essential to ensure food safety and human health. In this study, we developed a simple and rapid MXene/polypyrrole (PPy)-based bacterial imprinted polymer (MPBIP) sensor for ultrasensitive measurement of Salmonella . The mixture of pyrrole, MXene, and Salmonella was electrochemically polymerized onto a glassy carbon electrode. After immersion in the eluent to remove the Salmonella template, the established bacteria-imprinted sites on the surface of the polymer matrix enabled highly selective and specific recognition of Salmonella . Electrochemical impedance changes on the electrode surface can be used to detect target bacteria. MXene increased the electrical conductivity of PPy films and facilitated the elution of Salmonella templates (5 min). MPBIP's affinity for bacteria was enhanced by MXene's interaction with bacterial surface groups. The factors affecting the response of the sensor were investigated and optimized. Under the optimized conditions, the prepared bacteria-imprinted polymer sensor showed a good linear relationship with the logarithmic concentration of Salmonella in the range of 10 3 ∼ 10 7 CFU/mL with a detection limit of 23 CFU/mL. The sensor effectively distinguished Salmonella from other non-target bacteria and was well practical. The recoveries ranged from 96 % to 109.4 % for real samples, indicating the potential use of the sensor in food safety and environmental monitoring.

Conductivity improvement of magnetite and hematite nanoparticles via admicellar polymerization of polypyrrole

Polypyrrole (PPy) was used to obtain a coating on magnetite (Fe3O4) and hematite (Fe2O3) iron oxide nanoparticles (IONPs). PPy was synthesized on the surface of IONPs by admicellar polymerization for enhancement of electrical conductivity. Low surfactant and monomer levels enabled formation of films on the order of 1 nm thickness. The hydrophobic tendency of the modified IONPs was observed by aggregation in water and exclusion of water molecules. Coated IONPs were characterized by Fourier transform infrared spectroscopic techniques (FT-IR) and scanning electron microscopy (SEM) with particle size distribution analyzed by dynamic light scattering (DLS). Thermal stability of PPy-coated IONPs was investigated by thermogravimetric analysis (TGA). Lastly the magneticity and electrical conductivity of the modified IONPs were analyzed by VSM and multimeter measurements of packed IONPs in a circuit, respectively. Modified IONPs significantly enhanced electrical conductivity with greater effect related to the amount of PPy film coated on the IONP surface. Particle sizes of magnetite and hematite were found within the range between 50 and 2000 nm, depending upon PPy coating. The electrical property was successfully improved, but magnetic properties werenotstatisticallydifferentfrom the bare IONPs. The concentration of Py monomer at 30 mM shown as the critical concentration of both magnetite and hematite had the achievement of the high electrical conductivity.

Near-infrared radiation and heat dual-induced self-healing polyurethane with anti-abrasion ability

Disulfide bonds are widely used in self-healing materials owing to their dynamic nature under mild conditions. However, their practical application is severely limited by their low tensile strength. In this work, a linear polyurethane (CHPU) containing disulfide bonds and crystalline polycaprolactone diol is designed and synthesized. The infiltration of polypyrrole (PPy) nanoparticles endows the CHPU/0.5PPy nanocomposites with a high tensile strength (26.23 MPa), high toughness (119.71 MJ/m3), and a remote self-healing ability that can be triggered by heat or low-intensity (near-infrared) NIR radiation. A cut CHPU/0.5PPy film can recover 77.35% and 64.77% of its original tensile strength under 808 nm NIR radiation (118.46 mW/cm2) and 50 °C, respectively. In addition, CHPU/0.5PPy can bear 300 reciprocating linear abrasion cycles (0.5 N load force) with a stable friction coefficient, delivering a performance superior to those of many commercial anti-abrasion polyurethane coatings.

PANi/PPy and PANi Films on ZnNi Alloy Coated Carbon Steel; Electrochemical Syntheses and Corrosion Performances

Zinc–nickel alloy coating (ZnNi) was successfully deposited on carbon steel (CS) applying current density of 47 mAcm-2 with galvanostatic technique. The ZnNi alloy coating image showed that CS metal surface was plated with a blue-grey homogeneous layer. Polyaniline film (PANI) film was synthesized with cyclic voltammetry technique from 0.10 M aniline containing 0.20 M sodium oxalate solution on ZnNi coated carbon steel (CS/ZnNi) electrode surface. And then the synthesis of top PPy film was achieved in pyrrole monomer containing acetonitrile + tetrabutyl ammonium perchlorate medium successfully. After the top PPy synthesis, it was observed that both the PANi homopolymer film and the ZnNi coating continued to exist on the CS surface. The corrosion behaviors of uncoated and coated electrodes were investigated in 3.5% NaCl solution. For this aim, the anodic polarization plots and electrochemical impedance spectroscopy technique were used. The results showed that the top PPy homopolymer film provided an effective barrier property on CS/ZnNi/PANi electrode and a remarkable anodic protection to substrate for longer exposure time.

Synthesis and Characterization of Polypyrrole Film Doped with Both Molybdate and Salicylate and Its Application in the Corrosion Protection for Low Carbon Steel.

Polypyrrole (PPy) films doped with molybdate and salicylate have been successfully electropolymerized on low carbon steel in aqueous solutions containing both molybdate and salicylate in a one-step process that did not require any pre-treatment of the steel substrate. Salicylate-doped PPy films were synthesized in the same way for comparison. The steel surface was rapidly inhibited and the PPy-based films were formed on it easily. The PPy-based films were characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray, and thermal gravimetric analysis methods. The corrosion protection performance of the coatings was investigated with electrochemical impedance spectroscopy, open circuit potential (OCP), salt spray test, and Tafel polarization. It was found that in the presence of both molybdate and salicylate as dopants, the films on steel could present a better corrosion resistance than PPy film doped with only salicylate. The self-healing property of PPy-based films was observed on the OCP measurement with the fluctuation of rest potential. The salt spray test results showed that the PPy film doped with both salicylate and molybdate was more salt-resistant than the PPy film doped with only salicylate. The results suggest that the PPy coatings doped with both molybdate and salicylate are potential for application as metallic anti-corrosion coatings.

Influence of Polypyrrole Morphology on Gas Sensing

Polypyrrole with different morphologies has great impact over its properties such as concentration, time, high surface to volume ratio, dopants etc based on morphology has been discussed in this review. These Polypyrrole are potentially used for the sensing of various gases such as NO2, NH3, CO, H2 and CH4 gases. The influence of surface morphology, and doping of various PPy structures on gas sensing performance are extensively explained in this article such as roughness of films of PPy due to nature of counter ions influence the response of PPy films when used as sensitive layer, nanosheet structures has lowest LOD and improved response/recovery times. Furthermore, article focused upon various morphologies of PPy obtained with different methods and its influence in sensitivity is explained in this article. The sensitivity and response of PPy to various gases are also reviewed.

Electrolyte effect on the electroactuation behavior of multilayer polypyrrole films intercalated with TFSi−, ClO4−, NO3− anions in lithium and potassium based electrolyte solutions

We report on a comparative study on the electroactuation behavior of polypyrrole films doped with K+ and Li+ based electrolytes containing TFSi−, ClO4−, or NO3− anions. Multilayer polypyrrole-gold-polyvinylidene fluoride (PPy-Au-PVDF-Au-PPy) films were fabricated via electrooxidative pyrrole polymerization in a solution containing various lithium (LiTFSi, LiClO4, LiNO3) and potassium (KTFSi, KClO4, KNO3) electrolytes. The electroactuator behavior was tested in different media (air, Adriatic seawater, native electrolyte solutions, and Dulbecco's phosphate buffer saline solution). PPy films intercalated with KTFSi exhibited particulary good performance in air, remaining electroactive for over 40 days and withstanding over 230 actuation cycles while maintaining at least 50% of their original displacement capacity.

Study on the gas sensor at room temperature based on polypyrrole materials

This paper presents the results of synthesising polypyrrole (PPy) modified Dodecylbenzene sulfonic acid (DBSA) with nanostructures oriented to applications for NH3 gas sensors operating at room temperature. The outcomes of surface morphology and chemical composition structure analysis of PPy film were studied by field-emission scanning electron microscopy (FE-SEM), fourier-transform infrared spectroscopy (FT-IR), and ultraviolet-visible spectroscopy (UV-Vis). The products were obtained by electrochemical method with the nanostructured PPy film, the conductivity of the PPy film depends on the concentration of DBSA denaturant. The experimental results showed that these PPy films have a great potential application as a new sensitive layer for gas sensors.

Synergistic effects of chloride anions and carboxylated cellulose nanocrystals on the assembly of thick three-dimensional high-performance polypyrrole-based electrodes

Porous three-dimensional (3D) structures generally improve the performance of electrodes by increasing their active surface area and the diffusion speed of electrolyte ions during charging/discharging. Three-dimensional polypyrrole (PPy) based films were created by electrodepositing PPy in the presence of varying amounts of chloride anions (Cl−) and polyanionic ribbonlike nanoparticles (carboxylated cellulose nanocrystals (CNC-COO−)) as scaffold material. The assembly mechanism of the 3D PPy electrodes combines the effect of different nucleation and growth mechanisms during electropolymerization and deposition of the formed PPy with CNC-COO− and with Cl−. The highest area capacitance of these electrode materials was 1.39 F cm−2 (150.2 F g−1) at a current density of 1 mA cm−2 (0.1 A g−1). More importantly, at a high current density of 20 mA cm−2 (2.2 A g−1), the thick (ca. 130 μm), 3D, and high mass loading (9.2 mg cm−2) Cl−:CNC-COO−/PPy films exhibited an excellent areal capacitance of 0.85 F cm−2 (70.8 F g−1), increasing about 16% over CNC-COO−/PPy films prepared without Cl− present during electrodeposition. In addition, an aqueous Cl−:CNC-COO−/PPy (with Cl−:CNC-COO− = 2.0) symmetric supercapacitor had an outstanding energy density of 41.15 μWh cm−2 (4.46 Wh kg−1) and excellent cycling stability, while even improving on its original areal capacitance (to 111.2% of its original capacitance) after cycling 3000 cycles at 8 mA cm−2, indicating their potential in energy storage devices.

A synergistic Ti3C2Tx/PPy bilayer electrochemical actuator

Electrochemical actuators are devices that directly convert electrical energy into mechanical energy and have a wide range of applications. MXenes have high energy density, excellent rate performance, high electronic conductivity, strong mechanical strength, and can store ions through fast intercalation mechanism, making it a promising material for actuator applications. However, the restacking of MXenes layers limits ion percolation and thus limits the actuation performance. Polypyrrole (PPy) has a large volume deformation during its redox reaction process, but its low electrical conductivity and weak mechanical strength limit its practical application. Here, we logically designed an electrochemical actuator with Ti3C2Tx/PPy bilayer film as the electrode, and the Ti3C2Tx layer effectively improved the electrical conductivity of Ti3C2Tx/PPy and acted as the same time as current collector, co-actuation, and conductive additive, effectively accelerating the redox reaction rate of the PPy layer and increasing the performance. The curvature change of Ti3C2Tx/PPy bilayer film was improved by 57% (at 5 mV/s) in aqueous 1 M LiClO4 compared to the pure PPy film. After 10,000 cycles, 69.2% of the initial actuation performance can still be maintained. This research proves that this electrode structure design is feasible to improve the performance of actuators.

Corrosion protection properties of polypyrrole coatings formed onto 316 L SS from a solution containing molybdate and salicylate

The electrosynthesis of PPy films onto 316L stainless steel from nearly neutral and alkaline solutions containing molybdate and salicylate is reported. The corrosion behaviour of the coatings constituted by hollow rectangular microtubes was monitored in Ringer solution using open circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy. The polymer formed in a solution of pH 8 was the most efficient in terms of corrosion protection. The coating significantly reduced the pitting corrosion of the substrate. The results were interpreted taking into consideration the polymer electroactivity, the galvanic interaction polypyrrole/substrate and the nature of dopants. Silver species were effectively immobilized onto the hollow rectangular-sectioned microtubes of PPy. The modified coatings demonstrated that they have a good bactericidal activity against Escherichia coli and they were also able to protect the substrate against corrosion in Ringer solution.

High Crystalline Quality Conductive Polypyrrole Film Prepared by Interface Chemical Oxidation Polymerization Method

The authors report that polypyrrole (PPy) films with large area and high crystalline quality have been achieved using an interfacial chemical oxidation method. By dissolving different reactants in two immiscible solvents, the PPy is synthetized at the interface region of the two solutions. The PPy films have sharp XRD diffraction peaks, indicating that the molecular chains in the film are arranged in a high degree of order and that they reflect high crystalline quality. High crystal quality is also conducive to improving electrical conductivity. The conductivity of the as prepared PPy film is about 0.3 S/cm, and the carrier mobility is about 5 cm2/(Vs). In addition, the biggest advantage of this method is that the prepared PPy film has a large area and is easy to transfer to other substrates. This will confidently broaden the application of PPy in the future.

Uniform polypyrrole electrodeposition triggered by phytic acid-guided interface engineering for high energy density flexible supercapacitor

Unevenly distributed polypyrrole (PPy) films/coatings with extensive “dead volumes” via electrodeposition have emerged as a main challenge for high energy density flexible supercapacitor. In this work, we have fabricated a phytic acid-guided graphite carbon felt/polypyrrole (GF@PA@PPy) 3D porous composite with less “dead volumes” via electrodeposition. After the activation of phytic acid (PA), the quantity and content of defects and oxygen-containing groups on the surface of carbon felt (GF) have increased. First, these functional groups improve the hydrophilicity of the surface of GF, resulting in the preferential uniform distribution of pyrrole monomer (Py). While significantly, the synergistic effects between the defects and oxygen-containing groups boost the attraction of pyrrole ring, and thus promotes the formation of perfect PPy films with less “dead volume” on GF. Finally, the supercapacitor assembled from the GF@PA@PPy-40 displays a high areal energy density of 0.0732 mWh cm−2, exceeding the previously reported PPy-based electrodes values. The deeper understanding of the role for the defects and oxygen-containing groups in the synthesis of PPy/carbon materials offers a new strategy to construct advanced PPy-based supercapacitors.

Polymer‐Metal Oxide Composite (PPy–MoO3) for Ammonia and Ethanol Gas Sensor

AbstractPolypyrrole (PPy)–molybdenum trioxide (MoO3) is a polymer‐metal oxide composite (99.9% pure) obtained when two are mixed mechanically with different wt% in acetone medium to obtain different PPy–MoO3 composite materials. The thick films of pure PPy and PPy–MoO3 polymer‐metal oxide composite are prepared by screen printing technique. The prepared mixed composite polymer‐metal oxide materials are calcinated at 800°C for 8 h in air. The thick films are investigated for structural, electrical, and morphological properties. The surface morphology of the thick films is studied by scanning electron microscope (SEM) which shows that the films are granular and porous in nature. The gas responses of pure PPy and PPy–MoO3 polymer‐metal oxide composite thick films are studied for different gases such as ammonia gas (NH3) and ethanol gas at room temperature. The pure PPy thick film shows the poor response to ammonia and ethanol gas, while the thick film 40PPy–60MoO3 gave good responses to ethanol gas (50 ppm) at room temperature. The gas selectivity, sensitivity, stability, gas response, and recovery time of the sensor are measured and presented.

Enhanced electrochemical performance of electrosynthesized fibrillar polypyrrole film

Fibrillar polypyrrole film was electrosynthesised in the presence of Acid Blue 25. Chain organization of PPy was improved following a capacitance increase by one order of magnitude up to 1770 mF/cm2. Influence of AB25 augmented the electroactivity and stability of PPy films.