PPy Nanoparticles Research Articles

Facile synthesis of hierarchical nanostructured polypyrrole and its application in the counter electrode of dye-sensitized solar cells

Hierarchical nanostructured polypyrrole (HNPPy) of spherical polypyrrole (PPy) nanoparticles anchored on the surface of PPy nanofiber network is prepared by a facile process and incorporated into dye-sensitized solar cells (DSCs) as Pt-free counter electrode. This unique hierarchical nanostructure can provide the fast electron-transport pathway and abundant electrocatalytic active sites simultaneously. Electrochemical impedance spectroscopy analysis demonstrates that the electrocatalytic activity of HNPPy electrode for the I3− reduction is higher than that of PPy nanoparticles (PPyNPs) electrode and comparable to that of Pt electrode. As a consequence, the DSC fabricated with HNPPy counter electrode achieves a high conversion efficiency of 6.78%, which is close to the efficiency using Pt counter electrode.

Synthesis and application of carbowax/polypyrrole nanocomposite for fabrication of electrochemical sensor to detect 2,4-DNT vapor

In this study, an electrochemical sensor coated with carbowax/polypyrrole nanocomposite was fabricated so as to be sensitive to 2,4-dinitrotoluene (2,4-DNT) as a nitroaromatic explosive. The variation in electrical resistance was used as the mechanism by which the sensor responded to the concentration of explosive vapor. Polypyrrole (PPy) nanoparticles were synthesized and characterized using a scanning electron microscope (SEM), ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopy and x-ray diffraction analysis (XRD). The results showed that the fabricated PPy nanoparticles have a near spherical morphology with an average size of around 56 nm. The surface of the sensor template was then coated with a layer of nanocomposite composed of the synthesized PPy nanoparticles and carbowax polymer. Calibration and performance testing of the fabricated sensors were carried out with a special setup designed for explosive vapor generation under static conditions. The developed sensor was able to sense different concentrations of the explosive (0.5–100 ppm). The coated sensor showed a linear response in the concentration range of 0.5–50 ppm. The results showed that the designed sensor had a favorable sensitivity to the explosive. The calibration curve and sensitivity of the fabricated carbowax/PPy sensor was also determined in the explosive vapor concentration range of 0.5–50 ppm of 2,4-DNT under static conditions.

Spherical polypyrrole nanoparticles growing on the reduced graphene oxide-coated carbon cloth for high performance and flexible all-solid-state supercapacitors

A binder-free electrode based on spherical polypyrrole (PPy) nanoparticles growing on the reduced graphene oxide (RGO)-coated carbon cloth (CC) was fabricated and demonstrated its implementation for flexible all-solid-state supercapacitors (FSSCs). Graphene oxide (GO) was first coated on CC substrate by a facile dip-coating method, and then spherical PPy nanoparticles were grown on its surface and interior. The GO-coated CC provided an interconnected network for the growth of spherical PPy nanoparticles due to the good interfacial compatibility between GO and PPy. And the GO in the composite electrode was then reduced to obtain CC@RGO/PPy flexible electrodes. The as-prepared CC@RGO/PPy FSSCs exhibited better electrochemical performance than CC/PPy FSSCs. Furthermore, the flexible electrodes with uniform microstructures, large specific surface area and fine pore structure could be optimized and obtained through a dropwise adding method. The optimized CC@RGO/PPy FSSCs exhibited enhanced areal capacitance of 985mFcm−2 at 2mAcm−2, energy density of 1.10mWhcm−3 at the power density of 0.01Wcm−3 and good flexibility under bending condition. And the excellent electrochemical performance could be ascribed to the ingenious design and optimized structure of electrodes. The high-performance FSSCs have potential and promising application in the new generation of electronic devices.

Improvement of the electrocatalytic performance of platinum-free hierarchical Cu/polypyrrole/NiOx anode for methanol oxidation via changing the morphology of polypyrrole sublayer by self-assembled pyrrole monomers and overoxidation

Platinum-free electrocatalysts have been considered recently due to their low costs and high resistances against poisoning with reaction intermediates. In this work different electrocatalysts based on a matrix of polypyrrole, PPy, were examined for catalysis of methanol oxidation reaction, MOR. The copper substrates were covered by a PPy layer and NiOx nanoparticles were deposited electrochemically on it. The Cu/PPy/NiOx electrodes indicated catalytic performance for MOR. However, it was shown that the modification of the morphology of PPy, influenced its catalytic behavior. The self-assembly of pyrrole monomers on copper, prior to polymerization, led to the formation of tiny PPy nanoparticles between the common cauliflowers shaped PPy masses. The overoxidation was then carried out electrochemically and the PPy matrix encountered changes in morphology with micro/nano cracks. These changes in PPy morphology facilitated the diffusion of methanol electroactive species, which was verified by the cyclic voltammetry and electrochemical impedance spectroscopy results. The enhancement of active surface area and reduction of diffusion resistance for modified electrodes caused significant increment of their electrocatalytic performance. Scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction patterns were used for the characterization of the surface layers.

Self-Targeting, Immune Transparent Plasma Protein Coated Nanocomplex for Noninvasive Photothermal Anticancer Therapy.

Cancer cells exhibit specific physiological differences compared to normal cells. Most surface membranes of cancer cells are characterized by high expression of given protein receptors, such as albumin, transferrin, and growth factors that are also present in the plasma of patients themselves, but are lacking on the surface of normal cells. These distinct features between cancer and normal cells can serve as a niche for developing specific treatment strategies. Near-infrared (NIR)-light-triggered therapy platforms are an interesting novel avenue for use in clinical nanomedicine. As a photothermal agent, conducting polymer nanoparticles, such as polypyrrole (PPy), of great NIR light photothermal effects and good biocompatibility, show promising applications in cancer treatments through the hyperthermia mechanism. Autologous plasma proteins coated PPy nanoparticles for hyperthermia therapy as a novel core technology platform to treat cancers through secreted protein acid and rich in cysteine targeting are developed here. This approach can provide unique features of specific targeting toward cancer cell surface markers and immune transparency to avoid recognition and attack by defense cells and achieve prolonged circulation half-life. This technology platform unveils new clinical options for treatment of cancer patients, supporting the emergence of innovative clinical products.

Preparation of conductive, flexible and transparent films by in situ deposition of polypyrrole nanoparticles on polyethylene terephthalate

In this study polypyrrole (PPy) nanoparticles were deposited as a thin film on the modified surface of polyethyleneterephthalate (PET) by in situ chemical polymerization in the presence of sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (DBSNa) and mixture of them as the surfactant. The surface of PET was modified by KOH before deposition and was investigated for conductivity and adhesion of PPy nanoparticles to PET. Resulting conductive flexible films were characterized by UV–Vis spectroscopy, fieldemission scanning electron microscopy, contact angle measurements and four-point-probe technique for conductivity. Direct morphological observation (FESEM) and electrical measurements indicated that the morphology, conductivity and the nature of deposited PPy films depend on surfactant, surface modification of PET and monomer concentration. In optimized process condition, uniform conductive films of PPy were obtained with good adhesion to PET.

High electrical and electrochemical properties in bacterial cellulose/polypyrrole membranes

The purpose of the current work was to produce conducting electroactive membranes from bacterial cellulose (BC) coated with polypyrrole (PPy) via in situ chemical polymerization of pyrrole at 4°C using FeCl3 as oxidant agent. The electrical conductivity, tensile, thermal and electrochemical properties of BC-PPy membranes were investigated. The results revealed that the uniformly coating of PPy nanoparticles on the surface of BC template achieved high electrical conductivity of 3.39Scm−1 and a specific capacitance of 191.94Fg−1 at 5mvs−1 scan rate. The high conductivity and specific capacitance of the present BC-PPy membranes opens new potential applications for BC in various fields as biosensors, flexible electronics, or energy storage devices.

Polypyrrole-coated cotton fabrics used for removal of methylene blue from aqueous solution

PPy-coated cotton fabric was prepared in situ chemical polymerization using blends of anionic and cationic surfactants as soft template and investigated as adsorbent to remove dyes in the printing and dyeing wastewater. The PPy-coated fabric was characterized by scanning electronic microscopy and fourier transform infrared spectrum. It was found that the fiber and fabric surfaces were coated by PPy nanoparticles with diameters less than 100 nm which were quite loose and well formed as a three-dimensional network. Dye adsorption experiments demonstrated that the PPy-coated fabric could effectively remove MB dye and the decoloration capacity of MB solution could reach up to 95.6%. Factors influencing the adsorption of MB, e.g. ionic strength, solution pH, contact time, and adsorption mass, were systematically investigated. The adsorption capacity for MB dye increased gradually as its initial concentration increased. The batch experimental results suggested that the PPy-coated fabric could be used as an efficient sorbent to remove dyes in textile effluents.

A three-dimensional core-shell nanostructured composite of polypyrrole wrapped MnO2/reduced graphene oxide/carbon nanotube for high performance lithium ion batteries

Manganese oxides are promising anode materials for their high-energy density. However, they suffer from poor rate capability and fast capacity fading. Herein, we construct a three-dimensional (3D) core-shell structured polypyrrole (PPy)/MnO2-reduced graphene oxide (rGO)-carbon nanotubes (CNTs) composite via a facile two-step method. In the structure, the CNTs can facilitate fast electron conduction and keep structural integrity. The flexible and conductive rGO nanosheets work as both a reactive material and a carrier for MnO2 in-situ growth. The MnO2 nanosheets well distributed on the rGO/CNTs scaffold favor the energy storage by way of fast Li+ insertion and extraction. PPy nanoparticles (∼10nm) well wrapped on the MnO2 nanosheets not only enable the interfacial stabilization, but also provide a buffer layer to accommodate the volume expansion. As a result, the as-prepared PPy/MnO2-rGO-CNTs composite exhibits high specific capacity, excellent cycling stability and good rate capability. A reversible specific capacity of 1748.1mAhg−1 is achieved at the current density of 100mAg−1 after 200 cycles. Even at a high current density of 1000mAg−1, the composite still exhibits 941.1mAhg−1 after 1200 cycles. The design strategy of the composite can be extended to other high-capacity metal oxide material.

PPy@MIL-100 Nanoparticles as a pH- and Near-IR-Irradiation-Responsive Drug Carrier for Simultaneous Photothermal Therapy and Chemotherapy of Cancer Cells.

A medical nanoplatform with small size, low cost, biocompatibility, good biodegradability, and, in particular, multifunctionality has attracted much attention in the exploration of novel therapeutic methodologies. As an emerging material of self-assembled porous structure, metal-organic frameworks (MOFs) have high expectations because of their special properties compared to traditional porous materials. Therefore, integration of MOFs and functional materials is leading to the creation of new multifunctional composites/hybrids. Photothermal therapy (PTT), using near-IR (NIR) laser-absorbing nanomaterials as PTT agents, has shown encouraging therapeutic effects to photothermally ablate tumors. However, the most of widely used PTT agents are inorganic materials and nonbiodegradable. Herein, uniform polypyrrole (PPy) nanoparticles (NPs) with good biodegradability were synthesized by a microemulsion method. The PPy NPs were further coated with the mesoporous iron-based MOF structure MIL-100 by interaction between PPy NPs and MIL-100 precursors at room temperature. As a multifunctional nanoplatform, an anticancer drug could easily be loaded into the mesopores of the MIL-100 shell. The PPy core, as an organic photothermal agent, is able to photothermally ablate cancer cells and improve the efficacy of chemotherapy under NIR irradiation. The composites showed an outstanding in vivo synergistic anticancer capacity. Our work could encourage further study in the construction of a synergetic system using MOFs and organic PTT agents.

Facile preparation of polypyrrole-reduced graphene oxide hybrid for enhancing NH3 sensing at room temperature

Polypyrrole (PPy)-reduced graphene oxide (rGO) hybrid was successfully synthesized by a facile in situ polymerization. The as-synthesized PPy nanoparticles with diameter of ca. 80nm were uniformly distributed on the surface of the rGO sheets to prepare the hybrid of PPy/rGO. Then the pure PPy and their hybrids were loaded on the substrate of flexible polyethylene terephthalate (PET) film to construct a thin film NH3 sensor, which has the advantages of being flexible, economical, portable and able to operable at room temperature (RT). The gas-sensing results reveal that the 5wt% rGO-PPy hybrid based sensor not only exhibits the highest response to 10ppm NH3, which is 2.5 times higher than that of pure PPy, but also excellent selectivity to some of VOCs. The enhancement of gas-sensing properties may be attributed to the π-π stacking and H-bonding formation between PPy and rGO, larger surface accessibility and fast transport of carriers.

Fabrication of Polypyrrole Nanoparticles Using Microemulsion Polymerization for Diferent Py/APS/SDS Molar Ratios

Polypyrrole nanoparticles (PPy) were synthesized by the chemical oxidative microemulsion of pyrrole (Py) monomer using ammonium persulfate (APS) as an oxidant agent and sodium dodecylsulfate (SDS) as a surfactant at 28°C and 0°C. Different Py:APS:SDS molar ratios were used, and the properties of the resulting material were examined by four-probe DC electrical conductivity, ultraviolet-visible-near infrared (UV-vis-Nir), and Fourier-transform infrared (FTIR) spectroscopies as well as field-emission scanning electron microscopy (FESEM). UV-vis-Nir and FTIR spectra show the formation of a polaron band owing to the doping of PPy by SDS. The electrical conductivity and morphology of PPy nanoparticles depend on the synthesis conditions. Electrical conductivity of ~95.3×10-3 S/cm was achieved for PPy synthesized at 0°C. For the same Py:APS:SDS molar ratio, the nanoparticle shape changed from cylindrical to spherical upon simply lowering the synthesis temperature.

Conductive nanocomposites based on TEMPO-oxidized cellulose and poly(N-3-aminopropylpyrrole-co-pyrrole)

In this paper, conductive composite films were synthetized based on oxidized cellulosic nanofibres (CNFo), 1-(2-cyanoethyl)pyrrole and pyrrole. The 1-(2-cyanoethyl)pyrrole was reduced into N-(3-aminopropyl)pyrrole before being grafted on carboxyl groups of CNFo. Oxidative polymerization of polypyrrole (Ppy) was conducted in an iron(III) chloride (FeCl3) solution, onto the N-(3-aminopropyl)pyrrole grafted. The resulting composite films were characterized by FTIR-ATR Spectroscopy, scanning electron microscopy (SEM) equipped with energy-dispersive x-ray spectroscopy (EDX), tensile strength measurement, thermogravimetric analysis (TGA), wettability and electrical conductivity measurements. The grafting of 1-(2-cyanoethyl)pyrrole played a leading role in improving these properties by increasing potential connections between chains of conducting polymer and cellulose fibres. The outcomes show that the PPy nanoparticles coating on the grafted films increase a lot of characteristics of our composite such as wettability, mechanical properties, thermal protection and more importantly the electrical conductivity which was improved by a 10E5 factor in comparison to the uncoated films. In this condition, this nanostructure could be considered in the design of high-performance electrodes for supercapacitor, battery and sensor applications.

Synthesis and Characterization of Polypyrrole and Graphene/Polypyrrole/Epoxy Composites

Conducting polypyrrole (PPy) nanoparticles were synthesized via four different radical polymerization systems changing the time and other parameters. The characterization of PPy nanoparticles was done by Fourier transform infrared spectrometer. Graphene was synthesized from intercalated graphite by exfoliation at 1000\({^{\circ}}\) C for 30 s in tube furnace, and particle size was assessed using scanning electron microscope. Polypyrrole/graphene nano-composites were prepared by mixing PPy with graphene. Prior to this, graphene was coated with silane to enhance the bonding between PPy and graphene. The PPy-coated graphene composite was mixed in epoxy resin and cured using curing agent. The amount of PPy in nano-composites varied in the range of 1–20% by weight. The effect of PPy/graphene nanoparticles on mechanical and electrical properties and thermal stability of epoxy nano-composites was investigated. Thermal gravimetric analysis has shown that incorporation of PPy nanoparticles has improved the thermal stability of the epoxy nano-composites. Two probe electrical conductivity measurements have shown that increasing amount of graphene in PPy/epoxy nano-composites increases the conductivity of PPy significantly. In order to improve the dispersion of graphene in PPy, mechanical disperser was employed. Composites prepared with disperser have exhibited improvement in mechanical and thermal properties.

Mussel‐Inspired Conductive Cryogel as Cardiac Tissue Patch to Repair Myocardial Infarction by Migration of Conductive Nanoparticles

The engineered cardiac patch (ECP) is a promising strategy to repair infarct myocardium and restore the cardiac function. An ideal ECP should be able to mimic the primary attributes of native myocardium, which includes a high resilience, good cardiomyocyte adhesion, and synchronous contraction. Here, a mussel‐inspired dopamine crosslinker is used to integrate polypyrrole (Ppy) nanoparticles, gelatin‐methyacrylate, and poly(ethylene glycol) diacrylate into a cryogel form. The dopamine crosslinker and Ppy nanoparticles are coordinated to obtain optimal mechanical and superelastic properties for the ECP. The dopamine facilitates the uniform distribution of the Ppy nanoparticles, which migrate and fuse from the scaffold to the surface of the cardiomyocytes, revealing a potential mechanism for restoring infarct myocardium. The incorporated Ppy nanoparticles thus significantly enhance the functionalization of the cardiomyocytes, resulting in excellent synchronous contraction by increasing the expression of α‐actinin and CX‐43. Cardiomyocytes‐loaded ECP can improve the cardiac function in myocardial‐infarction (MI) affected rat models. The results show that the fractional shortening and ejection fraction are elevated by about 50% and that the infarct size is reduced by 42.6%. Collectively, this study highlights an effective cardiac patch based on mussel‐inspired conductive particle adhesion and a superelastic cryogel promising for the restoration of infarcted myocardium.

Nano-scale insulation effect of polypyrrole/polyimide core–shell nanoparticles for dielectric composites

The core–shell polypyrrole@polyimde (PPy@PI) particles were prepared and investigated on their dielectric properties for all-organic dielectric composites. The individually insulated PPy nano particles were formed by nano-scale coatings, which were obtained through interfacial precipitation, where the negatively charged polyamic acid (PAA) interact and are precipitated on the positively charged PPy particles. PAA shell becomes PI shell on PPy particles to form PPy@PI core–shell via imidization. The core–shell structure of PPy@PAA was observed by transmission electron microscopy (TEM) with staining of particles. At the 15 wt% PPy in PPy@PI composite, the dielectric permittivity of over 100 was obtained with the electrical conductivity of 10−8 S/cm. High fractional use of PPy in dielectric layer as over 30 wt% PPy gave the ultra-high dielectric permittivity of 487. The loss tangent of PPy@PI is lower than 0.18 until 15 wt% PPy content.

RGO/MnO2/polypyrrole ternary film electrode for supercapacitor

The binder-free electrode is expected for developing supercapacitor with high energy density. By using the good conductivity and forming-film property of PPy (Polypyrrole) and RGO (Reduced Graphene Oxide), as well as the high capacitance of MnO2 and PPy, [RGO/MnO2+PPy]10 ternary film electrode with high capacitance and good flexibility is prepared by a filtration-directed self-assembly technique. PPy nanoparticles (PPy) and MnO2 nanoparticles (MnO2) are uniformly embedded in RGO matrix constructed by the RGO nanosheets, decreasing the agglomeration of PPy and MnO2 and the reassembling of RGO nanosheets. RGO and PPy improve the conductivity, the ion diffusion rate and the charge-transfer resistance of the [RGO/MnO2+PPy]10 ternary film electrode, thus making it shows high capacitance and good flexibility. The [RGO/MnO2+PPy]10 ternary film electrode with a mass ratio of RGO:MnO2:PPy = 2:1:2 delivers the highest specific capacitance of 682 F g−1 at a scan rate of 5 mV s−1 and good cycling stability with about 86% retention of its original capacitance after 1000 consecutive cycles. The superior performance of [RGO/MnO2+PPy]10 ternary film electrode is probably ascribed to the novel film structure, the synergistic effect among PPy, RGO and MnO2 and the high packing density of PPy and MnO2.

Holey graphene/polypyrrole nanoparticle hybrid aerogels with three-dimensional hierarchical porous structure for high performance supercapacitor

Holey graphene/polypyrrole hybrid aerogels (HGPAs) with three-dimensional (3D) hierarchical structure have been fabricated by freeze-drying holey graphene/polypyrrole hydrogels, which are assembled by using holey graphene (HG) nanosheets and polypyrrole (PPy) nanoparticles as assembling primitives. The as-prepared HGPAs materials show an interconnected and stable 3D porous network, and PPy nanoparticles uniformly embedded in the aerogel prevent the restacking of holey graphene (HG) nanosheets. The unique hierarchical porous structure and synergistic effect between PPy nanoparticles and HG nanosheets make HGPA hybrid aerogel electrode with a mass ratio of PPy/HGO = 0.75 exhibits high specific capacitance (418 F g−1) at a current density of 0.5 A g−1, extremely outstanding rate capability (80%) at various current densities from 0.5 to 20 A g−1 and good cycling performance (74%) after 2000 cycles in 1.0 M KOH aqueous electrolyte. Moreover, the effect of the PPy nanoparticle sizes in HGPAs on their electrochemical properties is also investigated, and PPy nanoparticles with relatively larger sizes are favorable of the good capacitive performance for the obtained electrodes. The facile and efficient preparation method for HGPAs electrodes may be developed for preparing other holey graphene-based hybrid aerogels with structure-controllable nanostructures.

Bendable and flexible supercapacitor based on polypyrrole-coated bacterial cellulose core-shell composite network

We report a bendable and flexible supercapacitor based on polypyrrole-coated core-shell bacterial cellulose composite networks. As an initial step, gel-type bacterial cellulose was transformed into individually ultrathin bacterial cellulose nanofibers (TOBC) with diameters of 3–5 nm, by using 2,2,6,6-tetramethylpylperidine-l-oxyl radical (TEMPO)-mediated oxidation and successive mild disintegration in water. And, PPy-TOBC core-shell nanofiber network electrodes were synthesized in situ by oxidative polymerization of pyrrole with iron (III) chloride on the TOBC nanofibers in aqueous medium. The PPy-TOBC core-shell nanofiber network electrode exhibited a high porosity (101 m2/g) and high conductivity (∼6.63 S/cm) due to the homogenous coating of PPy nanoparticles on the TOBC nanofiber network. The as-prepared PPy-TOBC supercapacitor cell, fabricated with PVDF-EMIMBF4 (1-Ethyl-3-methylimidazolium tetrafluoroborate) polymer electrolyte, showed a specific capacitance of 153 F/g and energy density of 21.22 Wh/kg at the current density of 0.2 A/g. Moreover, the PPy-TOBC supercapacitor exhibited an exceptionally good cyclic stability with ∼93% capacitance retention after 100 cycles; it also showed good bending stability due to the mechanical failure tolerance of the nanofiber-networked electrodes. The present approach is a versatile, inexpensive, and promising way to develop the cellulose-based nanofiber network electrodes for practical energy storage applications.

Single-Step Synthesis of Heparin-Doped Polypyrrole Nanoparticles for Delivery of Angiogenic Factor

To perform one-pot synthesis of heparin-immobilized polypyrrole (PPy) nanoparticles and evaluate the use of these nanoparticles for the delivery of VEGF. Heparin-stabilized synthesis of PPy nanoparticles was performed via oxidative polymerization. VEGF-bound PPy-heparin nanoparticles were delivered to endothelial cells and bioactivity of VEGF was assessed by Matrigel tube formation. Size-controllable synthesis of heparin-doped PPy nanoparticles was achieved, and heparin promoted the conjugation of VEGF. Angiogenic activity of the VEGF-conjugated PPy nanoparticles was verified. Heparin-doped PPy nanoparticles can be synthesized using one-pot reaction and provide a delivery platform by which VEGF can be conjugated onto.