Polypyrrole Nanowires Research Articles

Structural and Electronic Property Study of Polypyrrole Nanowires Synthesized by Electrochemical Method

Structural and Electronic Property Study of Polypyrrole Nanowires Synthesized by Electrochemical Method

Single-step synthesis of polypyrrole nanowires by cathodic electropolymerization

Polypyrrole nanowires are successfully fabricated with a one-step process by cathodic electropolymerization from an aqueous solution without templates and chemical additives. The method utilizes electrochemically generated NO+ to oxidize the neutral pyrrole monomers, making it possible to use oxidizable metal substrates, such as Cu and Ni. The synthesized nanowires are directly deposited on the substrate in the form of a thin film consisting of fine polypyrrole nanowires with a nanoporous and interconnected network structure. The growth kinetics of the polypyrrole nanowires was investigated by analyzing the effects of the chemical composition of the electrolyte and the synthesis time on the formation of polypyrrole nanowires. It was found that the polymerization process of pyrrole is very sensitive to the reactivity of radical cations. For a radical cation with high reactivity, the polypyrrole nanospheres are synthesized near the electrode in the solution. In contrast, for a radical cation with sufficiently low reactivity, the polypyrrole nanowires are grown on the priorly deposited polypyrrole nanospheres.

Carbon nanotube reinforced polypyrrole nanowire network as a high-performance supercapacitor electrode

A carbon nanotube reinforced polypyrrole nanowire network was constructed by in situ polymerization of pyrrole in the presence of carbon nanotubes using cetyltrimethylammonium bromide micelles as a soft template. Carbon nanotubes as a reinforcer were embedded into a network of polypyrrole nanowires, thus retaining in the latter a complete network. The resulting network possessed a specific surface area of 112.1 m2 g−1 and a rough porous structure. The embedding of carbon nanotubes decreased the charge transfer resistance in the polypyrrole nanowires and allowed easy access and rapid diffusion of ions/electrons. When applied as a capacitive electrode, a specific capacitance of 183.2 F g−1 was observed at a current density of 8 A g−1. The specific capacitance retention was 85% after 1000 cycles at 1 A g−1. An asymmetric supercapacitor was fabricated using the network as a positive electrode and active carbon as a negative electrode, and when operated at a maximum voltage of 1.5 V, had a high energy density (15.1 W h kg−1 at 3000 W kg−1). A long-term cycling test of the asymmetric supercapacitor at a current density of 1 A g−1 displayed a capacitance retention of 72% even after 3000 cycles of charge and discharge.

Enhanced drug loading capacity of polypyrrole nanowire network for controlled drug release

For a conducting polymer (CP) based drug release system, drug loading is often accomplished by a doping process, in which drug is incorporated into polymer as dopant. Therefore, the drug loading capacity is relatively low and the range of drugs can be loaded is limited. In the present work, a polypyrrole (PPy) nanowire network is prepared by an electrochemical method and it is found that the micro- and nano-gaps among the individual nanowires of the PPy nanowire network can be used as reservoir to store drugs. Therefore, the drug loading capacity is dependent on the volume of these micro- and nano-vacancies, instead of the doping level. The range of loaded drugs also can be theoretically extended to any drugs, instead of only charged dopants. In fact, it is confirmed here that both hydrophilic and lipophilic drugs can be loaded into the micro- and nano-gaps due to the amphilicity of the PPy nanowire network. As a result, both drug loading capacity and the range of drugs can be loaded are significantly improved. After being covered with a protective PPy film, controlled drug release from the prepared system is achieved by electrical stimulation (cyclic voltammetry, CV) and the amount of drug released can be controlled by changing the scan rate of CV and the thickness of the protective PPy film.

High capacitive performance of flexible and binder-free graphene–polypyrrole composite membrane based on in situ reduction of graphene oxide and self-assembly

Exploiting flexible and binder-free electrode materials is of importance for the fast development of smart supercapacitor devices. A simple and effective strategy is demonstrated to fabricate a flexible composite membrane of reduced graphene oxide and polypyrrole nanowire (RGO-PPy) via in situ reduction of graphene oxide and self-assembly. More importantly, the shape and thickness of the membrane can be reasonably controlled by varying either the concentration of GO and PPy nanowires or the filtration volume. By direct coupling of two membrane electrodes, symmetric supercapacitors can be fabricated without the use of a binder and conductive additive. The supercapacitor is able to offer large areal capacitance (175 mF cm(-2)) and excellent cycling stability (~93% capacitance retention after 5000 charge-discharge cycles), thanks to the synergic integration between RGO sheets and PPy nanowires and the unique self-assembled porous structure.

Electrochemical synthesis of polypyrrole for biosensor application

Polypyrrole nanowires were electrochemically synthesised on platinum electrode at ambient temperature. The potentiostatic potential was set at 0.75 V in the presence of gelatin as soft mould. The whole process only took few hundred seconds. The morphologies, chemical composition and conductivity of nanowires were evaluated by means of Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and cyclic voltammetry (CV). The obtained nano-wire is around 50 nm in diameter with large surface, good conductivity. By surface enhanced Raman spectroscopy, the amine groups of polypyrrole were thought to be orientated upwards into the analyte which may facilitate the direct binding with DNA in DNA sensor.

Facile synthesis of SnO2-polypyrrole hybrid nanowires by cathodic electrodeposition and their application to Li-ion battery anodes

SnO2-polypyrrole hybrid nanowires are synthesized in a one-step process by a simple electrochemical method from an aqueous solution at room temperature. This novel and facile technique involves the rapid electropolymerization of pyrrole and the relatively slow chemical deposition of SnO2, which leads to the incorporation of uniformly dispersed SnO2 nanoparticles inside polypyrrole nanowires. Notably, the synthesized nanowires are directly deposited as a thin film on the substrate in a three-dimensional porous and interconnected network structure composed of numerous fine nanowires. This open architecture is highly desirable in energy storage devices because of its excellent mass transfer and high specific surface area, and therefore, the SnO2-polypyrrole hybrid nanowires are evaluated for their use as high-performance anode materials in Li-ion batteries. Over 200 cycles, the hybrid nanowires show superior cyclic performance and a charge capacity higher than 0.307 mA h cm−2, most likely because the polypyrrole matrix effectively prevents the agglomeration of the SnO2 nanoparticles and elastically buffers the volumetric change in the nanoparticles that occurs during cycling.

Vertically oriented polypyrrolenanowire arrays on Pd-plated Nafion® membrane and its application in direct methanolfuel cells

Highly ordered polypyrrole nanowire arrays are constructed via electrochemically polymerizing pyrrole directly on Pd-modified Nafion® membrane. A significant enhancement in the performance and durability of direct methanol fuel cells (DMFCs) is observed when such an ordered structure is used as an ordered electrode.

Seaweed-like porous carbon from the decomposition of polypyrrole nanowires for application in lithium ion batteries

High yield porous carbon is prepared via the chemical oxidative polymerization of pyrrole and subsequent the decomposition of polypyrrole nanowires with KOH activation. The obtained carbon materials take on a seaweed-like porous morphology. The effects of the KOH mass and activation temperature on the morphology, structure and electrochemical performance of the porous carbon materials are studied in detail. When evaluated for the electrochemical properties in lithium ion batteries as anode materials, one of the unique porous products exhibits an ultra-high reversible capacity of about 1010.2 mA h g−1 at the first cycle and excellent capacity retention in the following cycles.

PH sensors based on polypyrrole nanowire arrays

The hydroquinone monosulfonate-doped polypyrrole (PPy-HQS) nanowires were successfully fabricated by potentiostatic electropolymerization of pyrrole (Py) inside the pores of home-made through-hole anodic aluminum oxide (AAO) membranes. The AAO templates with a nominal pore diameter of 80nm were prepared by a two-step anodization process. The potentiostatic electropolymerization of HQS-doped polymer nanowires was carried out in 0.1M NaClO4, or 0.1M LiClO4 or 0.1M citric acid containing 0.05M pyrrole and 0.05M potassium hydroquinone monosulfonate. The synthesized PPy-HQS nanowire arrays were tested as potential potentiometric pH sensors. It was found that pH sensors based on PPy-HQS nanowires exhibited better electrochemical performance toward pH sensing than those based on PPy-HQS thin films. The best potentiometric response to pH changes and a very good stability in time showed the sensor based on the PPy-HQS nanowires polymerized in a 0.1M LiClO4 solution.

Nonenzymatic biosensor based on CuxO nanoparticles deposited on polypyrrole nanowires for improving detectionrange

CuxO (CuO and Cu2O composite) nanoparticles modified polypyrrole (PPy) nanowires were fabricated and used as a biosensor for detecting glucose (GLC). PPy nanowires were prepared through electrodeposition, while CuxO nanoparticles were deposited on PPy nanowires by electrodeposition and electrochemical oxidation in situ. The scanning electron microscopy images showed the CuxO nanoparticles aligned along the PPy nanowires uniformly and the average size of CuxO nanoparticles is about 90nm. The electrocatalytic activity of CuxO/PPy/Au towards GLC was investigated under alkaline conditions using cyclic voltammetry and chronoamperometry. The sensor exhibited a linear range up to 8mM of GLC, which is more than two times of most of the existing non-enzymatic GLC sensors based on CuO or Cu2O. The sensitivity of the sensor is 232.22μAmM−1cm−2 and detection limit is 6.2μM (at signal/noise=3). Moreover, the sensor showed excellent selectivity, reproducibility and stability properties. These excellent performances make CuxO/PPy/Au a good nonenzymatic GLC sensor.

Prospective of Conducting Polymer Nanowire for Gas Sensing Application to its Physical Scaling

The effect of physical scaling on one dimensional (1-D) conducting polypyrrole (Ppy) nanowire device has been successfully studied. The synthesis, electrical characterization and ammonia gas sensing with 1-D Ppy nanowire device have been carried out in the present investigation. Ppy nanowires having ~80 to ~200 nm in diameter were synthesized by electrochemical polymerization in alumina template and 1.77 to 3 µm Ppy nanowire length were maintain by varying the distance between electrodes gap. We further demonstrated that gas sensors based on 1-D Ppy nanowire having high aspect ratio (length to diameter ratio, L:D) exhibits good sensitivity towards ammonia, and provided a reliable detection at concentration as low as approximately 1 ppm based on principal of physical scaling co-related to response resistance.

Modification of polypyrrole nanowires array with platinum nanoparticles and glucose oxidase for fabrication of a novel glucose biosensor

A novel glucose biosensor, based on the modification of well-aligned polypyrrole nanowires array (PPyNWA) with Pt nanoparticles (PtNPs) and subsequent surface adsorption of glucose oxidase (GOx), is described. The distinct differences in the electrochemical properties of PPyNWA–GOx, PPyNWA–PtNPs, and PPyNWA–PtNPs–GOx electrodes were revealed by cyclic voltammetry. In particular, the results obtained for PPyNWA–PtNPs–GOx biosensor showed evidence of direct electron transfer due mainly to modification with PtNPs. Optimum fabrication of the PPyNWA–PtNPs–GOx biosensor for both potentiometric and amperometric detection of glucose were achieved with 0.2M pyrrole, applied current density of 0.1mAcm−2, polymerization time of 600s, cyclic deposition of PtNPs from −200mV to 200mV, scan rate of 50mVs−1, and 20 cycles. A sensitivity of 40.5mV/decade and a linear range of 10μM to 1000μM (R2=0.9936) were achieved for potentiometric detection, while for amperometric detection a sensitivity of 34.7μAcm−2mM−1 at an applied potential of 700mV and a linear range of 0.1–9mM (R2=0.9977) were achieved. In terms of achievable detection limit, potentiometric detection achieved 5.6μM of glucose, while amperometric detection achieved 27.7μM.

Hybrid nanotubes: Single step formation of homogeneous nanotubes of polypyrrole-gold composites and novel switching transition of resistance beyond liquid nitrogen temperature

Nanowires of polypyrrole have exhibited switching transition that reduces the resistance of the wires by several orders of magnitude under certain bias around and below 30 K temperature. Here, we have shown that by incorporating gold in these polypyrrole nanotubes using a cost effective template based single-step chemical synthesis technique, this novel resistance switching transition could be extended beyond liquid nitrogen temperature (>90 K) to make this phenomena technologically relevant. The single step synthesis technique, reported here, provides us uniform mixing of gold and polypyrrole during the formation of composite-nanotubes; with appropriate choice of materials, this synthesis technique can be extended to form nanotubes of other metal-polymer composites.

Facile fabrication of conducting polymer nanowire based field effect transistor with controlled shape and position

Graphical abstractDisplay Omitted Highlights? Single conducting polymer nanowire is fabricated directly on the device platform. ? Facile method provids the controlled position, width, and length of nanowire. ? Nanowire is electrochemically deposited on the nanopatterned area of electrode. ? Polypyrrole nanowire based field effect transistor is successfully established. In this paper, a facile method by which conducting polymer nanowire can be fabricated directly on the device platform in controlled position, width, and length is proposed. Conducting polymer was electrochemically deposited on the nanopatterned area of a working electrode. The shape and position of the nanowire, in particular the length of the nanowire can be easily controlled by modulation of the nanopatterned area via lithography method. Through the proposed fabrication method, a polypyrrole nanowire based field effect transistor was successfully established. This fabrication design provides an easy way to manufacture the conducting polymer nanowire based devices in controlled manner, and the devices are suitable for application in chemical and biological sensors as well as organic electronics.

Facile synthesis of SnO2 nanocrystals coated conducting polymer nanowires for enhanced lithium storage

SnO2 nanoparticles uniformly decorated polypyrrole (PPy) nanowires are synthesized by a facile two-step electrochemical reaction method: electropolymerization and electrodeposition. The nanostructured SnO2–PPy hybrids show porous reticular morphology and homogenous distributions. The reticular SnO2–PPy nanowires can increase the electrode/electrolyte interface and accommodate the volume variation of SnO2. When applied as anode materials for lithium ion batteries, the unique nanostructured hybrids deliver meaningfully improved Li+ storage performance with the first reversible capacity of 690 mAh g−1. This facile synthesis procedure can also be simply grafted to other inorganic–organic hybrid composites.

Morphology of Polypyrrole Prepared in SDS Solution

Polypyrrole (PPy) nanowires and bundles were successfully synthesized by changing the concentration of the monomer in sodium dodecyl sulfate (SDS) solution. The obtained PPy was characterized by SEM, FT-IR and XRD. The results showed that the PPy was amorphous although their morphology was different and some surfactant molecules were doped into the polymer chains as counterions.

Electropolymerized Polypyrrole Nanowires for Hydrogen Gas Sensing

In this report, polypyrrole nanowires have been successfully deposited on interdigitated transducers through template-free electropolymerization. The nanowires were 40–90 nm in diameter according to scanning electron microscopy analysis, and some of them were bridging the insulating gaps between gold electrodes. An X-ray photoelectron spectroscopy study has been conducted to determine the chemical composition of the synthesized nanomaterial. The developed sensors were tested toward five concentrations of hydrogen gas at room temperature, and their sensitivities were compared. Due to the very high surface area of the deposited sensitive films, these sensors provided faster response compared to other polypyrrole-based gas sensors. Moreover, it is shown that the sensors’ sensitivities are related to the amount of the deposited PPY nanowires.

Effect of polypyrrole on improving electrochemical performance of silicon based anode materials

► Si/PPy composites for lithium ion battery have been synthesized. ► PPy of two microstructures acting as matrix have been synthesized and characterized. ► Two kinds of PPy show different effects on improving electrochemical performance. ► Si/nano-wires PPy shows an improved electrochemical performance. Silicon and polypyrrole composites with different microstructures of polypyrrole were synthesized using high-energy mechanical milling. The nano-wires polypyrrole and micro-particles polypyrrole act as a matrix to hold the active silicon grains as they repeatedly alloy with lithium during the operation of a lithium ion battery. The composite containing 10 wt.% polypyrrole nano-wires exhibits a relative better reversibility and cycle life than bare silicon, while the silicon/micro-particles polypyrrole composite shows no improvement.

Synthesis of graphene oxide/polypyrrole nanowire composites for supercapacitors

Polypyrrole (PPy) nanowires have been successfully grown on the surface of graphene oxide (GO) nanosheets by using a facile chemical method. The GO/PPy composites exhibit a predominant specific capacitance of 633F/g at a current density of 1A/g by charge/discharge analysis, in comparison with 227F/g for pure PPy. The composites also show superior electrochemical rate capability and cycle stability. The attenuation of the specific capacitance is less than 6% after 1000 charge/discharge processes. The high specific capacitance and good stability of the GO/PPy composites are very promising for applications in electrochemical supercapacitor devices.