Polypyrrole Nanostructures Research Articles

Improvement of Electrical Conductivity of In Situ Iodine-Doped Polypyrrole Film Using Atmospheric Pressure Plasma Reactor with Capillary Electrodes.

To improve the electrical conductivity of polypyrrole (PPy) nanostructure film through in situ iodine (I2) doping, this study proposes an atmospheric pressure plasma reactor (APPR) where heated I2 dopant vapor is fed through capillary electrodes that serve as electrodes for discharge ignition. A large amount of the heated I2 vapor introduced into the reactor separately from a monomer gas can be effectively activated by an intense plasma via capillary electrodes. In particular, intensive plasma is obtained by properly adjusting the bluff body position in the APPR. Based on the ICCD and OES results, the I2 vapor injected through the capillary nozzle electrode is observed to form I2 charge species. The formed I2 species could directly participate in growing in situ I2-doped PPy films. Thus, in situ I2-doped PPy nanostructure films grown using the proposed APPR exhibit higher thicknesses of 15.3 μm and good electrical conductivities, compared to the corresponding non-doped films.

Highly Electroactive Frozen-State Polymerized Polypyrrole Nanostructures for Flexible Supercapacitors.

The polymerization of pyrrole in the frozen state with the presence of organic dyes (methyl orange (MO) and Acid Blue 25 (AB)) has proven to produce polypyrrole (PPy) nanostructures. Herein, we explore the electrochemical properties of PPy prepared under frozen-state conditions (-24 °C) with and without the presence of organic dyes. The electroactivity of PPy prepared with MO and AB significantly increased in all electrolytic media with a capacitance higher than this of the PPy prepared at room temperature. The highest capacitance (1914 F g-1) was obtained for PPy-MO in 0.2 M HCl solution. The impedance spectra of PPy showed a decrease in charge transfer resistance when the dyes were present. This indicates a conductivity increase of PPy. Improved electrochemical stability was observed for PPy, PPy-MO, and PPy-AB prepared at -24 °C, wherein a steady gain of capacitance was maintained during 5000 potential cycling. In addition, a PPy-based supercapacitor device was fabricated to demonstrate the energy storage characteristics of PPy, where it showed good capacitive behavior and stability. Overall, frozen-state polymerized PPy posed an impressive capacitive performance for flexible supercapacitors.

A study on surfactant modified polypyrrole nanostructures and its applications in supercapacitors

Nanocomposites of Polypyrrole (Ppy), were synthesized by chemical oxidative polymerization of pyrrole, in the presence of mono and mixed‐surfactant solutions using ammonium persulfate as an oxidant and were investigated for its applications in super capacitors. The surfactants used in the experiments included anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS) and cationic surfactants, tetradecyltrimethylammonium bromide (TTAB) as well as cetyltrimethylammonium bromide (CTAB). The morphology and structure of the resulting Ppy were investigated in detail with FESEM and FTIR, respectively. The addition of anionic surfactants produced globular morphology. The results showed that the interaction between the different surfactants and the interaction between the surfactants and the polymer influenced the morphology, structure and conductivity of the resulting polymer to different degrees. Apart from these, XRD, UV-Vis spectroscopy and cyclic voltammetry (CV) were also performed to characterize the prepared composites. In comparison with the results for mono surfactant solutions, the polymerization of pyrrole in mixed‐surfactant solutions shows significant changes in morphologies and electrochemical properties of Ppy. The results of CV show that the specific capacitance values of Ppy samples with anionic surfactants are greater than cationic surfactants. In case of mixed surfactants, sample with SDBS + TTAB posses highest specific capacitance of 204 Fg−1 at scan rate 100 mVs−1. The good electrochemical properties can be attributed to the highly porous structural advantage of the Ppy sample prepared using SDBS + TTAB. It indicates the energy holding capacity or capacitance of the prepared samples and can be utilized in sensing applications like supercapacitors.

Synergy and Symbiosis Analysis of Capacity-Contributing Polypyrrole and Carbon-Coated Lithium Iron Phosphate Nanostructures for High-Performance Cathode Materials

To address the existing problems of commercial inorganic cathodes, including relatively low capacity, poor rate performance, structural instability, and low conductivity, it is critical to introduce a conductive matrix accompanied with electrochemical activity. Conductive polymers have great potential as electrodes with good conductivity, high redox activity, and potential. In this study, carbon-coated lithium iron phosphate (C-LiFePO4) nanoparticles were effectively dispersed in a polypyrrole (PPy) matrix by in situ pulverization. PPy, as an active nanostructure, significantly improves conductivity and accelerates Li+ diffusion. To further explore the synergy and symbiosis mechanism of PPy and C-LiFePO4 (hereinafter called C-LFP in the composite), the nanoparticle dispersion, carburization dependence, and heat treatment preference were investigated. Therefore, a reasonable amount of PPy (25 wt %) hybridization, a moderately wrapped carbon buffer layer (5.3 wt %), and a suitable heat treatment (100 °C) were employed to prepare the (C-LFP)0.75(PPy)0.25 nanocomposite. With a smaller particle size, uniformly dispersed morphology, and good synergy effect between PPy and C-LiFePO4, (C-LFP)0.75(PPy)0.25 delivers a high discharge capacity (209.1 mAh g–1 at 0.1C), a superior rate capability (86.1 mAh g–1 at 10C), and an outstanding capacity retention (83.5% of the initial values after 500 cycles at 0.5C).

Flexible, ultrathin and light films from one-dimensional nanostructures of polypyrrole and cellulose nanofibers for high performance electromagnetic interference shielding

Combining highly conducting one-dimensional nanostructures of polypyrrole with cellulose nanofibers (CNF) into flexible films with tailored electrical conductivity and mechanical properties presents a promising route towards the development of eco-friendly electromagnetic interference shielding devices. Herein, conducting films with a thickness of 140 μm were synthesized from polypyrrole nanotubes (PPy-NT) and CNF using two approaches, i.e., a new one-pot synthesis consisting of in situ polymerization of pyrrole in the presence of structure guiding agent and CNF, and a two-step synthesis, in which CNF and PPy-NT were physically blended. Films based on one-pot synthesis (PPy-NT/CNFin) exhibited higher conductivity than those processed by physical blending, which was further enhanced up to 14.51 S cm−1 after redoping using HCl post-treatment. PPy-NT/CNFin containing the lowest PPy-NT loading (40 wt%), thus the lowest conductivity (5.1 S cm−1), displayed the highest shielding effectiveness of −23.6 dB (>90 % attenuation), thanks to the good balance between its mechanical properties and electrical conductivity.

Conjugated Polymer Polypyrrole Nanostructures: Synthesis and Photocatalytic Applications.

Conjugated polymers (CPs) have been recently widely investigated for their properties and their applications in different fields including photocatalysis. Among the family of CPs, polypyrrole (PPy) has been the most extensively studied owing to its good environmental stability, high electrical conductivity, superior redox properties and easy synthesis. Besides, nanostructured polypyrrole-based nanomaterials are a type of active organic materials for photocatalysis, which is one of their emerging applications. Nanostructuration of polypyrrole can reduce the electron-hole recombination because of short charge transfer distances and reactant adsorption, and product desorption can be enhanced owing to the high surface area offered by nanostructures. This review summarizes synthesis of different nanostructures based on π-conjugated polymer polypyrrole and the latest developments for photocatalytic applications, including degradation of organic pollutants and hydrogen generation.

On the functionality of the polypyrrole nanostructures for surface modification of Co-free Li-rich layered oxide cathode applied in lithium-ion batteries

Co-free Li-rich manganese nickel oxide (LMNO) materials are emerging as an up-and-coming candidate for high-energy–density cathodes. However, they suffer from severe cycling capacity fading and poor performance rates. Herein, the surface functionalization of an LMNO cathode is designed by polypyrrole (PPy) nanostructure coating. We found that PPy [email protected] cathode exhibits high-capacity retention and enhanced rate capabilities, delivering a discharge capacity as high as 191 mAh g−1, with capacity retention of 96%, after ∼ 200 cycles at a current density of 20 mA g−1. The results indicate that the intercalation and doping pseudocapacitance can be varied depending on the synthesis process, morphology (nanowire/nanorod/nanoparticle), size, dispersity, and weight percentage of PPy. Our findings provide an effective strategy to improve the ionic and electronic conductivity of LMNO cathodes and demonstrate that high-capacity and long cycle-life Li-ion batteries can be achieved by regulating the contribution of the intercalation and doping pseudocapacitive charge storage behavior.

High-performance one and two-dimensional doped polypyrrole nanostructure for polymer solar cells applications

High-performance one and two-dimensional doped polypyrrole nanostructure for polymer solar cells applications

Superior photocatalytic activity of polypyrrole nanostructures prepared by radiolysis in water and dichloromethane

Conjugated polymers have emerged as very active photocatalysts under visible light. Among these materials, nanostructured polypyrrole (PPy) has recently been used as photocatalyst for degradation of environmental pollutants under UV as well as visible light. In the present study, we specifically explored the photocatalytic activity of conducting PPy synthesized by radiolysis, either in water (PPyH2O) or in dichloromethane solvent (PPyDCM), in the absence of any external dopant or template. The successful preparation of both kinds of conducting polymers was confirmed by complementary spectroscopic techniques and morphological characterizations. Besides, the photocatalytic activity of both materials was evaluated in the degradation of phenol as model pollutant in aqueous solution. PPyH2O as well as PPyDCM were found to exhibit remarkably high photocatalytic activity under both UV and visible light. These organic photocatalysts remain very stable after several cycles and thus, easily reusable. Interestingly, PPyDCM clearly appears as the most efficient photocatalyst due to its longer chain length, highly doped nature, lower optical band gap and extended absorption band from the UV to the near infrared region. The present work definitely validates radiation chemistry as an alternative approach to synthesize conducting polymer-based photocatalysts. The obtained results also highlight that the radiosynthesized PPy, especially those prepared in dichloromethane, constitute promising candidates for photocatalytic depollution of water.

Effect of polypyrrole nanostructures on the anti-corrosion performance of polypyrrole/polyvinyl butyral/carbon black coatings

Polypyrrole nanoparticles (PPy NPs), nanorods (NRs), and nanotubes (NTs) are prepared by a green chemical oxidation method using H2O2 as an oxidant under UV irradiation. The anti-corrosion coatings are prepared by hybridizing different nanostructured PPy, polyvinyl butyral, and carbon black for protecting zinc metal. The effect of the content of PPy on corrosion-resistant of the coatings is investigated, and the influence of the PPy nanostructures on the anti-corrosion performance of the coatings is also investigated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. It is found that the composite coatings with nano-PPy have obvious anticorrosive performance, and the corrosion resistance is evidently enhanced with the increase of the content of PPy nanostructures. It is further found that the coatings containing PPy NPs have the best corrosion resistance. The possible anti-corrosion mechanism of the anti-corrosion coatings is proposed.

Revealing the unexplored effect of residual iron oxide on the photoreforming activities of polypyrrole nanostructures on plastic waste and photocatalytic pollutant degradation

Nanostructured conducting conjugated polymer, polypyrrole was synthesized via a template free approach. Residual α-Fe2O3 was found in the polypyrrole matrix when FeCl3 was used as the oxidant for polymerization of pyrrole. Importantly, the α-Fe2O3 exists in polypyrrole as nanoparticles forming a heterojunction nanocomposite that significantly improves the photocatalytic activity of the polymer under visible light. Photocatalytic activity of the nanocomposite was multifold higher than metal free polypyrrole and α-Fe2O3. The nanocomposite showed high photocatalytic activity in photoreforming of plastic to hydrogen and other value-added organic products. Furthermore, the photoreforming does not produce any greenhouse gases like CO2. Using the method reported herein, the amount of residual α-Fe2O3 in conducting polymer matrix can be tuned and optimized to yield promising photocatalysts for green and sustainable development.

Enhancing Optical and Electrical Gas Sensing Properties of Polypyrrole Nanoplate by Dispersing Nano-Sized Tungsten Oxide

Pure polypyrrole (PPy) and tungsten oxide (WO3) nanostructures were produced and combined with specific ratios of WO3. to prepare PPy-WO3 hybrid nanocomposite thin films using the drop-casting process on a silicon substrate. The morphology of PPy, WO3, and PPy-WO3 was examined by field emission scanning electron microscopy and we found that the substance is nanoplates. Due to the quantum confinement effect, the optical energy gap of PPy increased from 3.58 eV to 3.92 and 4.21 eV upon incorporating 10 and 20% of WO3, respectively. At ambient temperature, the DC-conductivity of synthetic PPy was found to be 7.3 × 10−2 S cm−1 and this significantly increases when WO3 is added, which is accompanied by a change in the activation energies of the hybrid nanocomposite. The response and recovery times, as well as the sensitivity as a function of time and operating temperature, of pure PPy nanoplate and PPy-WO3 hybrid nanocomposites films for nitrogen dioxide (NO2) sensing were investigated. The PPy-WO3 hybrid nanocomposites exhibited a lower response time and higher sensitivity than pure PPy. The enhancement in the sensitivity of the PPy-WO3 hybrid nanocomposites to NO2 is ascribed to the synergistic effect between PPy and WO3.

Long-Term Stable Near-Infrared-Short-Wave-Infrared Photodetector Driven by the Photothermal Effect of Polypyrrole Nanostructures.

Polypyrrole (PPy) is a conductive polymer and widely applied in different applications owing to its broadband absorption in the UV-visible, near-infrared (NIR), and short-wave-infrared (SWIR) spectrum, excellent conductivity, and strong photothermal effect. In this work, we explored for the first time the photothermal effect of PPy nanoparticles (PPy-NPs) in a photothermal-induced detector structure and developed a new type of air-stable hybrid PPy-NPs/Pt photodetector (PD) with NIR/SWIR sensitivity. By combining PPy-NPs with a platinum (Pt)-resistive pattern, we fabricated PPy-NPs/Pt PDs that are sensitive to illumination in the wavelength range from 800 to 2000 nm. Under the illumination of λ = 1.5 μm, the maximum photoresponsivity was measured to be ∼1.3 A/W with a 131 μs photoresponse rise time. Owing to the excellent material stability from both PPy-NPs and the Pt pattern, the current photodetectors show long-term stable photoresponsivity when they were stored in air without encapsulation. The results suggest that the PPy-NPs/Pt hybrid PDs are promising candidates for a new type of low-cost and broadband due to their multiple advantages such as free of toxic heavy metals, air stability, and solution processing.

A new high-performance supercapacitor electrode of strategically integrated cerium vanadium oxide and polypyrrole nanocomposite

Herein we show a construction of high-performance supercapacitor electrode made of cerium vanadate uniformly glazed over polypyrrole (CeVO4/Ppy) nanostructures by a simple hydrothermal method, which was characterized by various analytical techniques. Electrochemical studies on CeVO4/Ppy/Ni foam with 1 M KOH show a maximum specific capacitance of 1236 F/g at a current density of 0.75 A/g. These salient features, together with smart interactions between the interconstituents, CeVO4 and Ppy, lead to high conductivity, specific capacitance, and cycling stability with retention of 92.6% capacitance in 10,000 cycles of GCD curves. Additionally, the asymmetric supercapacitor based on activated carbon (AC), AC//CeVO4/Ppy device delivers a high specific capacitance of 116 F/g and energy density of 52.2 Wh/Kg at power density of 675.9 W/kg along with high capacity retention of 77.80% after 10,000 cycles. This system could be scaled up to large-scale production of high power devices, which opens up lot of opportunities in modern electronic industrial applications.

Nitrogen-Containing Tubular Hollow Carbon Frameworks: A Nongraphitic Carbon for a Robust Room Temperature Hydrogen Gas Sensing Application

We report, for the first time, polypyrrole-derived nitrogen-containing tubular hollow carbon (NTHC) frameworks for hydrogen (H2) gas sensing application. NTHC was synthesized simply by pyrolysis of tubular polypyrrole nanostructure, which developed carbon nanostructure of high surface area with numerous micromesopores. The surface of the carbon nanostructure was uniformly decorated with platinum nanoparticles (Pt NPs). The Pt/NTHC sensor, fabricated using a facile drop-casting method, shows good repeatability and complete recovery at room temperature and achieves twofold higher sensitivity compared to Pt NPs dispersed multiwalled carbon nanotubes. The sensor shows interesting gas sensing behavior (conversion of p-type to n-type) during exposure to H2. The possible role of N-doping type in the sensing behavior is discussed.

Electrochemical bubble generation via hydrazine oxidation for the in situ control of an electrodeposited conducting polymer micro/-nanostructure.

Herein, a simple, in situ, on step and highly repeatable electrochemical method that allows controlling the nanostructure of electrodeposited polymer films is reported. As an example, the tuning of the electrodeposited polypyrrole nanostructures using inert gas bubbles as the template at the electrode surface generated by the electrochemical oxidation of hydrazine is shown. The hydrazine discharge occurs at a lower potential regarding the beginning of pyrrole electropolymerization process, which allows the modulation of the density and size of the bubbles on the surface electrode controlling electrochemical parameters (applied potential, concentration, time, etc.). Subsequently, the applied potential is moved to where the pyrrole polymerization begins, which induces the material discharges around the bubble template producing polypyrrole hollow structures with definite patterns on the electrode surface. This methodology is proposed as a simple model for the electrodeposition with the morphological control of a wide range of conductive polymers.

Conversion of conducting polypyrrole nanostructures to nitrogen-containing carbons and its impact on the adsorption of organic dye

New types of materials were produced by gradual heating of a conducting polymer, polypyrrole, to elevated temperatures.

Organic Surfactant Assisted Polypyrrole Materials as Effective Chemiresistive Gas Sensors for VOCs and Toxic Gas Detection

Surfactant assisted PPy materials are explored as efficient gas sensors for VOCs and toxic gases in the present work. Polypyrrole nanostructures were prepared by chemical oxidative polymerization using various sulfonic acids as surfactants between 0-5 °C. The effect of sulfonyl group on PPy was confirmed by FT-IR spectrum analysis. Doping of sulfonic acid has a strong effect on morphology of polymer blends which displayed the amorphous, globular, cauliflower, flakes and compact sheet like structures observed in the surface morphology. The conductivity of doped PPy observed to be dependent on the nature of dopant and its doping level. The electrical conductivity was observed to enhance by an order in magnitude on the addition of organic surfactants from 0.1 to 2.0 M. The pristine PPy shows high % response of 93% and 70% only for NH3 and Cl2 respectively. But different surfactant doped PPy were found to be highly sensitive for most of the VOCs and toxic gases which emerged as efficient sensor materials for fast response and recovery at the lowest level of 5 ppm.

One-Dimensional Nanostructures of Polypyrrole for Shielding of Electromagnetic Interference in the Microwave Region.

Polypyrrole one-dimensional nanostructures (nanotubes, nanobelts and nanofibers) were prepared using three various dyes (Methyl Orange, Methylene Blue and Eriochrome Black T). Their high electrical conductivity (from 17.1 to 60.9 S cm−1), good thermal stability (in the range from 25 to 150 °C) and resistivity against ageing (half-time of electrical conductivity around 80 days and better) were used in preparation of lightweight and flexible composites with silicone for electromagnetic interference shielding in the C-band region (5.85–8.2 GHz). The nanostructures’ morphology and chemical structure were characterized by scanning electron microscopy, Brunauer–Emmett–Teller specific surface measurement and attenuated total reflection Fourier-transform infrared spectroscopy. DC electrical conductivity was measured using the Van der Pauw method. Complex permittivity and AC electrical conductivity of respective silicone composites were calculated from the measured scattering parameters. The relationships between structure, electrical properties and shielding efficiency were studied. It was found that 2 mm-thick silicone composites of polypyrrole nanotubes and nanobelts shield almost 80% of incident radiation in the C-band at very low loading of conductive filler in the silicone (5% w/w). Resulting lightweight and flexible polypyrrole composites exhibit promising properties for shielding of electromagnetic interference in sensitive biological and electronic systems.

Electrochemical Deposition of Polypyrrole Nanostructures for Energy Applications: A Review

By collecting and analyzing relevant literature results, we demonstrate that the nanostructuring of polypyrrole (PPy) electrodes is a crucial strategy to achieve high performance and stability in energy devices such as fuel cells, lithium batteries and supercapacitors. In this critic and comprehensive review, we focus the attention on the electrochemical methods for deposition of PPy, nanostructures and potential applications, by analyzing the effect of different physico-chemical parameters, electro-oxidative conditions including template-based or template-free depositions and cathodic polymerization. Diverse interfaces and morphologies of polymer nanodeposits are also discussed.