PPy Nanofibers Research Articles

Synthesis of PPy-MnO2 Nanocomposite for Utilization in Supercapacitor Applications

Polypyrrole (PPy) nanocomposites were prepared using chemical oxidation and were combined with manganese oxide (MnO2) nanoparticles. The PPY-MnO2 nanocomposite was synthesized by integrating PPy nanofibers with varying volume ratio percentages of MnO2 dopant (10, 30, and 50% vol. ratio). The structural features of the PPy and PPy-MnO2 nanocomposite were investigated using X-ray diffraction (XRD). Fourier transfor infrared (FTIR) spectroscopy was used to demonstrate the molecular structures of primary materials and the final product of PPy, MnO2, and PPy- MnO2 nanocomposites. Field Emission Scanning Electron Microscopy (FESEM) showed that the morphology of PPy consisted of a network of nanofibers. Increasing the volume ratios of manganese oxide added to the PPY nanofiber led to the increase of manganese oxide nanoparticles on the surface of the PPY nanofiber network. This resulted in a noticeable alteration in the structure of the nanocomposite. It has been observed that the nanocomposites demonstrate a significant level of pseudocapacitive activity. The highest capacitance of 236 F/g was observed when pure PPy was doped with 30% MnO2 compared to 125 F/g of the pure PPy.

Role of Efficient Charge Transfer at the Interface between Mixed-Phase Copper-Cuprous Oxide and Conducting Polymer Nanostructures for Photocatalytic Water Splitting.

Photocatalytic hydrogen generation from water splitting is regarded as a sustainable technology capable of producing green solar fuels. However, the low charge separation efficiencies and the requirement of lowering redox potentials are unresolved challenges. Herein, a multiphase copper-cuprous oxide/polypyrrole (PPy) heterostructure has been designed to identify the role of multiple oxidation states of metal oxides in water reduction and oxidation. The presence of a mixed phase in PPy heterostructures enabled an exceptionally high photocatalytic H2 generation rate of 41 mmol h-1 with an apparent quantum efficiency of 7.2% under visible light irradiation, which is a 7-fold augmentation in contrast to the pure polymer. Interestingly, the copper-cuprous oxide/PPy heterostructures exhibited higher charge carrier density, low resistivity, and 6 times higher photocurrent density compared to Cu2O/PPy. Formation of a p-p-n junction between polymer and mixed-phase metal oxide interfaces induce a built-in electric field which influences directional charge transfer that improves the catalytic activity. Notably, photoexcited charge separation and transfer have been significantly improved between copper-cuprous oxide nanocubes and PPy nanofibers, as revealed by femtosecond transient absorption spectroscopy. Additionally, the photocatalyst demonstrates excellent stability without loss of catalytic activity during cycling tests. The present study highlights a superior strategy to boost photocatalytic redox reactions using a mixed-phase metal oxide in the heterostructure to achieve enhanced light absorption, longer charge carrier lifetimes, and highly efficient photocatalytic H2 and O2 generation.

OER catalytic performance of a composite catalyst comprising multi-layer thin flake Co3O4 and PPy nanofibers.

The oxygen evolution reaction (OER) plays a crucial role in energy conversion and storage processes, highlighting the significance of searching for efficient and stable OER catalysts. In this study, we have developed a composite catalyst, PPy@Co3O4, with outstanding catalytic performance for the OER. The catalyst was constructed by integrating multi-layer thin flake Co3O4 with attached PPy nanofibers, utilizing the rich active sites of Co3O4 and the flexibility and tunability of PPy nanofibers to optimize the catalyst structure. Through comprehensive characterization and performance evaluation, our results demonstrate that the PPy@Co3O4 (0.1 : 1) catalyst exhibits remarkable OER catalytic activity and stability. This research provides new strategies and insights for the development of efficient and stable OER catalysts, holding promising prospects for energy conversion and storage applications in relevant fields.

The significance of doping in enhancing polypyrrol nanofiber storage ability as a supercapacitor

Polypyrrol was prepared by electrochemical polymerization. Polypyrrol morphology has been investigated by FE-SEM and it shows a polypyrrol nanofibre network. By doping PPy nanofibers with different MW-CNT proportions (10%, 20%, 30%, 40% vol.ratio), nanocomposites were obtained. When adding MW-CNT with PPy, the nanotubes particles on the nanofibre network gradually grew in proportion to added ratio, and hence a clear change in the nanocomposite structure was observed. The electrochemical measurements indicate that the nanocomposites demonstrate strongly pseudocapacitive activity. The capacitance of pure PPy was (19.23 Fg-1), while the maximum value of capacitance (153 Fg-1) was observed when 30% MW-CNT was doped with pure PPy.

Conducting Polymer-Based Nanohybrids for Fuel Cell Application.

Carbon materials such as carbon graphitic structures, carbon nanotubes, and graphene nanosheets are extensively used as supports for electrocatalysts in fuel cells. Alternatively, conducting polymers displayed ultrahigh electrical conductivity and high chemical stability havegenerated an intense research interest as catalysts support for polymer electrolyte membrane fuel cells (PEMFCs) as well as microbial fuel cells (MFCs). Moreover, metal or metal oxides catalysts can be immobilized on the pure polymer or the functionalized polymer surface to generate conducting polymer-based nanohybrids (CPNHs) with improved catalytic performance and stability. Metal oxides generally have large surface area and/or porous structures and showed unique synergistic effects with CPs. Therefore, a stable, environmentally friendly bio/electro-catalyst can be obtained with CPNHs along with better catalytic activity and enhanced electron-transfer rate. The mass activity of Pd/polypyrrole (PPy) CPNHs as an anode material for ethanol oxidation is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy. The Pd rich multimetallic alloys incorporated on PPy nanofibers exhibited an excellent electrocatalytic activity which is approximately 5.5 times higher than monometallic counter parts. Similarly, binary and ternary Pt-rich electrocatalysts demonstrated superior catalytic activity for the methanol oxidation, and the catalytic activity of Pt24Pd26Au50/PPy significantly improved up to 12.5 A per mg Pt, which is approximately15 times higher than commercial Pt/C (0.85 A per mg Pt). The recent progress on CPNH materials as anode/cathode and membranes for fuel cell has been systematically reviewed, with detailed understandings into the characteristics, modifications, and performances of the electrode materials.

The fabrication of hierarchical nanostructured graphene/PPy fiber composites and its electrochemical properties

The graphene/PPy fiber nanocomposites were synthesized via a facile one-step solvothermal method. Moved by electrostatic interaction and hydrogen bonding between the tetra-functional NiPcTs and PPy chain, a self-sorting mechanism acts to align the PPy chains to form one-dimensional PPy nanofibers on graphene. The in situ grown nanostructure possesses a good interconnectivity and porosity facilities. The well-designed microstructure of the composites achieves a synergistic effect between the graphene and PPy and shows a good electrochemical performance for supercapacitors of 316 F g−1 even at a high current density of 5 A g−1.

Performance of interdigitated capacitive-type CO2 sensor based on polypyrrole/copper phthalocyanine nanocomposite

In this study, we present the performance of interdigitated capacitive-type gas sensor devices based on polypyrrole/copper phthalocyanine (PPy/CuPc) nanocomposite, for sensing of CO2 gas at room temperature. In this framework, the PPy/CuPc nanocomposites have been synthesized by a simple in situ chemical oxidation polymerization in the presence and absence of cationic surfactant. The synthesized samples have been analyzed using field emission scanning electron microscopy and Fourier-transform infrared spectroscopy in order to study surface morphology and nanocomposite formation. The interaction of developed gas sensors with CO2 was registered by the change in capacitance. Under exposure to CO2 gas in the range of 0.1–1% at room temperature, all fabricated sensor show reversible, reproducible, and linear response. Particularly, the PPy/CuPc nanocomposite containing highly interconnected network of PPy nanofibers exhibits higher response and sensitivity toward CO2 gas compared to particle-like PPy/CuPc nanocomposite and pure PPy. The long-term stability of gas sensor devices have also been examined in particular concentration of CO2 gas within 30 days by monitoring the change in capacitance response. The sensing performance of the capacitive-type gas sensor based on the PPy/CuPc nanocomposite may be of interest for CO2 detection in future studies.

Enhanced solar hydrogen generation using Cu–Cu2O integrated polypyrrole nanofibers as heterostructured catalysts

Nanostructured conducting polymeric materials are beneficial for electron conduction and mass transport, showing high photocatalytic performance under visible light. Herein, we report a colloidal synthesis of copper and copper oxides (Cu2O) modified polypyrrole nanofibers (PPy) heterostructures, which demonstrates significantly high photocatalytic H2 generation under visible light. The presence of Cu nanoparticles (NPs) of 50 nm and cubic shaped Cu2O nanoparticles of size 200 nm endows the heterostructures with a large specific surface area as well as good dispersion of nanoparticles on PPy nanofibers allows the migration of electron during catalysis. Cu2O/PPy exhibits excellent H2 production (67 mmol h−1) which is 12 times higher than pure PPy (5.7 mmol h−1). The high catalytic activity of Cu2O/PPy heterostructure provides a fervent alternative to noble metal-based catalysts for the hydrogen generation and water splitting.

Functionalized conjugated polymer with plasmonic Au nanoalloy for photocatalytic hydrogen generation under visible-NIR

Abstract Gold based multimetallic nanoalloys decorated on conjugated polymer nanofibers have been prepared using a greener approach without using any reducing agent. The as-prepared nanohybrids exhibited superior catalytic activity for solar hydrogen production under visible light (λ > 420 nm) irradiation and near infrared light irradiation. The UV–Visible diffuse reflectance spectra displayed strong absorption in the visible region which significantly favours the photocatalytic performance. Furthermore, the efficient charge separation suggested by electrochemical impedance measurement and photocurrent response curves for Au50Pt24Pd26/PPy nanohybrids which exhibited significant enhancement in H2 generation rate compared to Au/PPy nanohybrids. The strong interface contact between Au nanoalloys and PPy nanofibers play an important role for the migration of electron during catalysis. The Mott–Schottky plot revealed that photo generated charge carrier concentration has been increased for Au50Pt24Pd26/PPy nanohybrids (7.93 × 1011cm−3) compare to pure PPy (1.43 × 1011 cm−3). The present study provides a new prospect for using conducting polymer based hybrid as photocatalysts for efficient solar hydrogen production.

Hierarchical core/shell bamboo-like polypyrrole nanofibers/Fe3O4 hybrids with superior microwave absorption performance

ABSTRACTDesign and fabrication of structurally optimized microwave absorbing materials are important for eliminating electromagnetic (EM) pollution. Herein, we reported the novel highly regulated core/shell bamboo-like polypyrrole (PPy) nanofibers/Fe3O4 hybrids as the efficient microwave absorbing materials. Typically, the target hybrid materials were prepared by a two-step method, including synthesis of bamboo-like PPy nanofibers using vapor polymerization of PPy on tubular vanadium pentoxide templates and coprecipitation of Fe3O4 nanoparticles on the surface of bamboo-like PPy nanofibers. Owing to good impedance matching and hierarchical structure, as-prepared core/shell bamboo-like PPy nanofibers/Fe3O4 hybrids exhibit superior microwave absorption and broad absorption bandwidths compared with conventional PPy/Fe3O4 composites. The lowest reflection loss of core/shell bamboo-like PPy nanofibers/Fe3O4 hybrid is calculated to be −41.6 dB at 10.0 GHz with the thickness of 2.5 mm. Furthermore, the absorption bandwidths exceeding −10 dB are more than 8.0 GHz with thickness of 2.0–3.5 mm. Therefore, this work provides an efficient way to obtain high-performance microwave absorber with lightweight, strong absorption and wide absorption bandwidths.

Surface Structure-Dependent Low Turn-On Electron Field Emission from Polypyrrole/Tin Oxide Hybrid Cathodes.

We present a new surface structure-dependent cold cathode material capable of sustaining high electron emission current suitable for next-generation low turn-on field-emission devices. The low turn-on electric field for electron emission in the cathode materials is critical, which facilitates the low-power room-temperature operation, a key factor required by the industrial sector. We demonstrate the facile synthesis of polypyrrole (PPy)/tin oxide (SnO2)-based core–shell hybrid cold cathode materials for large area applications. The technique used here is based on a simple and economical method of surfactant-mediated polymerization. The coupled investigation of X-ray diffraction along with electron microscopy reveals the formation of rutile phase SnO2 nanoparticles of size ∼15 nm. These SnO2 nanoparticles act as nucleation sites for the growth of PPy nanofibers, resulting in encapsulated SnO2 nanoparticles in the PPy amorphous matrix. The coupling of spherical-shaped core–shell structures of PPy/SnO2 resulted into the particle train-like nanostructured form of the hybrid material. These core–shell structures formed the local p–n junction between the n-type SnO2 (core) and p-type PPy (shell). The long chains of these p–n junctions in nanofibers result in the modification of the electronic band structure of PPy, leading to a reduction in the work function of the electrons. The significant surface structural modification in PPy/SnO2 causes a prominent reduction in the turn-on electric field for electron emission in PPy/SnO2 nanocomposite (∼1.5 V/μm) as compared to the pure PPy (∼3.3 V/μm) without significant loss in current density (∼1 mA/cm2). The mechanism of improved field-emission behavior and advantages of using such hybrid nanomaterials as compared to other composite nanomaterials have also been discussed in detail.

Highly Active Multimetallic Palladium Nanoalloys Embedded in Conducting Polymer as Anode Catalyst for Electrooxidation of Ethanol.

Fabrication of multimetallic nanocatalysts with controllable composition remains a challenge for the development of low-cost electrocatalysts, and incorporating metal-based catalysts into active carbon nanoarchitectures represents an emerging strategy to improve the catalytic performance of electrocatalysts. Herein, a facile method developed for Pd nanoparticle (NP)-based multimetallic alloys incorporated on polypyrrole (Ppy) nanofibers by in situ nucleation and growth of NPs using colloidal radiolytic technique is described. Electrochemical measurement suggests that the as-prepared catalysts demonstrate dramatically enhanced electrocatalytic activity for ethanol oxidation in alkaline medium. The ultrasmall Pd30Pt29Au41/Ppy nanohybrids (∼8 nm) exhibit excellent electrocatalytic activity, which is ∼5.5 times higher than that of its monometallic counterparts (12 A/mg Pd, 5 times higher activity compared to that of Pd/C catalyst). Most importantly, the ternary nanocatalyst shows no obvious change in chemical structure and long-term stability, reflected in the 2% loss in forward current density during 1000 cycles. The superior catalytic activity and durability of the nanohybrids have been achieved due to the formation of Pt-Pd-Au heterojunctions with cooperative action of the three metals in the alloy composition, and the strong interactions between the Ppy nanofiber support with the metal NPs. The facile synthetic approach provides a new generation of polymer-supported metal alloy hybrid nanostructures as potential electrocatalysts with superior catalytic activity for fuel cell applications.

Flexible MoS2 nanosheets/polypyrrole nanofibers for highly efficient electrochemical hydrogen evolution

Hierarchical MoS2 nanosheets/polypyrrole nanofibers (MoS2 NSs@PPy NFs) core/shell nanostructures were successfully fabricated through a simple and environmentally friendly method by using PPy nanofibers as the core and MoS2 NSs as the shell. The as-fabricated three dimensional MoS2 NSs@PPy NFs proved to be the effective hydrogen evolution reaction (HER) catalyst, which only needed 60 and 196 mV overpotential to approach 10 and 100 mA cm−2, respectively. Furthermore, a small Tafel slope of 33 mV dec−1 and low onset overpotential of 20 mV were achieved, which were smaller than the previously reported values. The MoS2 NSs@PPy NFs catalyst may hold great potential for practical applications.

Rational design of self-supporting graphene - Polypyrrole/sulfur - Graphene sandwich as structural paper electrode for lithium sulfur batteries

Lithium sulfur batteries have been regarded as next-generation battery technology due to its high energy density, environmental benignity and abundance. However, the poor electric/ionic conductivity of sulfur limits the practical use of sulfur in an electrode. The main problem is the high solubility of long-chain polysulfides, which are the intermediates of the electrochemical processes in the liquid electrolyte. The dissolved polysulfide ions shuttle between the cathode and anode, thus causing precipitation of insulating Li2S2/Li2S on the surface of the electrode. The unavoidable phenomenon results in loss of active materials and fast capacity fading. In this regard, we show one simple method to prepare free-standing paper electrode used as cathode material for lithium sulfur batteries. Binder-free graphene-polypyrrole (PPy)/S-graphene (G-PPy/S-G) paper-like sandwich structural electrode was prepared by using the vacuum filtration method. In this structure, the unique graphene layers of sandwich-like framework not only serve as a conductive film, but also effectively block the diffusion of polysulfides, leading to suppression of the shuttle effect and low self-discharge behaviour. In addition, the middle layer, the PPy nanofibers can limit the diffusion of dissolved polysulfides due to the special bond with sulfur, and furthermore maintain the structural stability of the paper electrode because the nanofibers can serve as elastic springs to accommodate the huge volume changes in charging-discharging processes. When tested as cathode for Li-S batteries, the as-prepared sample G-PPy/S-G exhibits excellent electrochemical performance. We believe that our strategy could provide a useful pathway towards commercial utilizing of sulfur.

Scalable and Low Cost Synthesis of Highly Conducting Polypyrrole Nanofibers Using Oil–Water Interfacial Polymerization under Constant Stirring

In the present work, we report a low cost and scalable oil-water interfacial polymerization method to synthesize one-dimensional (1-D) highly conducting polypyrrole (PPy) nanofibers doped with p-toluenesulfonic (p-TSA) and hydrochloric (HCl) acids. Polymerization of pyrrole (monomer) has been carried out at the interface formed between the immiscible oil and aqueous water droplets under constant magnetic stirring at room temperature. Formation of smaller diameter (16-20 nm) PPy nanofibers has been confirmed from the high resolution transmission electron microscopy (HRTEM) studies, and the average diameter of p-TSA doped PPy nanofibers is found to be smaller than that of HCl doped nanofibers. The polymer chain ordering or crystallinity of both p-TSA and HCl doped PPy nanofibers have been studied with X-ray diffraction (XRD). Studies of Fourier transform infrared (FTIR) spectra suggest the presence of all the characteristic vibration bands in doped PPy nanofibers. The doping of PPy nanofibers has been confirmed from the formation of polaron and bipolaron bands in their UV-vis spectra. The optical band gap energy (Eg) and Urbach energy (EU) for PPy nanofibers doped with p-TSA and HCl doped PPy nanofibers were determined from their UV-vis absorption spectra. The red shift of the polaron absorption band in p-TSA doped PPy nanofibers confirms a higher conjugation length of the polymer nanofiber chains than that in the HCl doped PPy nanofibers. Thermogravimetric (TGA) and derivative plots of TGA studies predict that PPy nanofibers doped with p-TSA are thermally and structurally more stable as compared to HCl doped PPy nanofibers. Current-voltage (I-V) characteristics exhibit nonlinear behavior with voltage in both p-TSA and HCl doped PPy nanofibers.

Fabrication and characterization of poly(butyl acrylate-co-methyl methacrylate)-polypyrrole nanofibers

In the present work, poly(buty acrylate-co-methyl methacrylate)/polypyrrole P(BA-co-MMA)/PPy nanofibers were produced by using electrospinning method. FTIR–ATR measurements indicated the presence of PPy in the composite nanofiber structure. Scanning electron microscopy (SEM) images showed that the diameter of nanofibers was dependent on PPy content and the fiber diameter was decreased with increasing initial pyrrole concentration. A relation between contact angle and diameter of nanofibers which is related with PPy content was observed. P(BA-co-MMA)/PPy4 which has the highest amount of PPy, exhibited the smallest fiber diameter and the highest contact angle. Mechanical properties of P(BA-co-MMA)/PPy became poor compared to P(BA-co-MMA). By the increase of PPy content in the nanofibers, increase in the alternating current (AC) conductivities was observed. In addition, the AC conductivity of nanofibers was increased with frequency, particularly in the higher frequency region.

Synergistic Effects of Polypyrrole Nanofibers and Pd Nanoparticles for Improved Electrocatalytic Performance of Pd/PPy Nanocomposites for Ethanol Oxidation

The development of advanced materials is a central issue to accelerate the implementation of fuel cell technology which constitutes immense potential to meet future power sources. In this work, a facile, one-pot synthesis of Pd nanoparticles (NPs)/polypyrrole (PPy) nanofiber composites has been reported using oxidative complexes as soft templates. Average size of Pd NPs within the PPy nanofibers was found to be in the range of 2.2–4 nm as measured from transmission electron microscopic (TEM) image. The NPs possess good degree of crystallinity as discernible from the lattice fringes in high-resolution transmission electron microscopy (HRTEM), and the cubic crystal phase was ascertained from the X-ray diffraction (XRD) pattern. Electrochemical measurements like cyclic voltammetry (CV) and chronoamperometry (CA) measurements demonstrate that the Pd NP-based polymer nanocomposites (PNCs) show superior electrocatalytic activity for ethanol oxidation and higher stability compared to the commercial Pd/C catalysts which suggest the significant advantages of polymer support over carbon support. The enhanced electrochemical performance attributed with low charge-transfer resistance of the composite catalyst facilitates an easier access of ethanol molecules to the catalytic sites. The mass activity of Pd/PPy nanocomposites is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy composites. The effective dispersion of the Pd NPs within the conducting polymer nanostructures allowed an enhancement of the catalytic activity. Our adopted method could be suitable for further development of advanced anode catalyst for alkaline fuel cell applications.

Simultaneous Multi-Analyte Detection of Neurotransmitters Using Polypyrrole-Based Molecularly Imprinted Conducting Polymers

This work reports on the selective multi-analyte detection of neurotransmitters using polypyrrole based molecularly imprinted polymer (MIP) sensors. A LabVIEW-based differential pulse voltammetry (DPV) method is designed for the simultaneous detection of multiple analyte. Two types of MIP-based sensors, namely the dopamine (DA)-imprinted and the norepinephrine (NE)-imprinted polymers, were prepared using pyrrole as a functional monomer. The ability to detect multiple neurotransmitters simultaneously can provide the critical information about many psychiatric disorders such as Parkinson's Disease and Alzheimer's Disease. Electrochemical detection method is one of the most effective techniques for neurotransmitter sensing because of the high sensitivity and portability. However, the similar redox potential among the neurotransmitters cause poor selectivity in detection. Molecularly imprinting technique provides a highly selective method for neurotransmitters sensing. Figure 1 illustrates the basic principle for MIP technique. Polypyrrole (PPy) was used as a functional polymer because of the good conductivity and ease of synthesis. Multi-walled carbon nanotubes (MWCNTs) were introduced as a platform (or a template) for PPy growth because of the strong affinity between MWCNTs and the PPy as well as the excellent electrical property. DA and NE molecules served as templates, and each type of MIP was synthesized in a similar way. The template molecule was embedded inside the PPy layers. After being overoxidized with several cyclic voltammetry (CV) cycles, the templates were removed from the PPy layer which created cavities corresponding to the shape and size of the analyte. Therefore, the MIPs are able to enhance the sensitivity and selectivity of the sensor. Although there have been recent work on MIP-based sensors, most of them have focused on single analyte detection. Therefore, a novel method for multi-analyte sensing is urgently needed for commercial applications. In order to achieve this goal, this work presents a LabVIEW-based multi-species detection system. Figure 2 shows the design of the circuit for the potentiostat system. The sensor consists of two working electrodes (WE1 and WE2), a reference electrode (RE), and a counter electrode (CE). The generated DPV signal was connected to the two working electrodes, and MIPs were deposited on the working electrode for detection. The MIP synthesis method was designed as follows, H2O2 was added to the mixture of pyrrole monomer, CNT, FeCl2, and template solutions (either DA,or NE) at room temperature. After the MIPs was fully synthesized, deionized water was used to wash out the unreacted substance. Finally, the MIPs were overoxidized in phosphate buffered saline (PBS 1X) solution to remove the embedded template molecules. Figure 3 shows the DPV responses for (a) DA-imprinted device (DA-MIP) and (b) NE-imprinted device (NE-MIP) when exposed to various concentrations of DA. DA-MIP and NE-MIP were connected to WE1 and WE2, respectively. Although oxidation peaks were observed in both sensors, the DA-MIP device produced a greater sensitivity at 0.02V. However, NE-MIP device exhibited better performance at 0.26V when two types of MIP device (c), (d) were exposed to various concentrations of NE solutions. Figure 4 shows a set of calibration curves for both DA-MIP and NE-MIP incubated in DA figures (a – c), and NE (d – f) solutions. Each sensor exhibited higher sensitivity for their respective target analyte. Also, the sensitivity of the sensor can be affected by the present of other species, the performance of the sensors varies when exposed to different mixtures. Figure 5 summarizes the multi-analyte performance for two MIP devices simultaneously exposed to a mixture of two analyte. The slope of the calibration curve was obtained for each combination of mixtures, where the slope indicated its sensitivity. The response of DA-MIP device was significantly higher than the NE-MIP device for all cases when the concentration of DA was varied. On the other hand, NE-MIP device usually possesses better sensitivity than the DA-MIP device when the concentration of NE was varied. In summary, the selectivity of both MIP devices toward their own species have been confirmed, and the results demonstrate that the molecularly imprinted cavities inside the PPy nanofibers can selectively measure the quantity of the target analyte even in the presence of other interfering molecules. We envision that a highly selective multi-analyte detection of a large number of analytes is also possible by implementing multiple types of MIP-based electrochemical sensors on a single chip. Figure 1

Morphology control of conducting polypyrrole nanostructures via operational conditions in the emulsion polymerization

ABSTRACTPolypyrrole (PPy) nanostructures with diameter smaller than 100 nm were synthesized by chemical oxidative polymerization of pyrrole in the presence of cetyl trimethylammonium bromide and sodium dodecyl sulfate as surfactants. Hydrochloric acid was used as dopant, and a solution of potassium peroxydisulfate was used as initiator. The influence of polymerization temperature, feeding strategy, and the type of surfactant on the morphology and conductivity of PPy nanostructures were investigated and well‐described. A simple route just via controlling the operational conditions in the emulsion polymerization is reported to obtain nanostructured PPy with desirable morphology and relatively good conductivity. The analysis results demonstrated that the conductivity of samples is highly affected by their morphology whereas PPy nanofibers exhibited higher conductivity respecting the other morphologies (0.66 S/cm). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44697.

Utilization of Polypyrrole Nanofibers in Glucose Detection

The present work demonstrates a novel, simple approach for fabrication of sensitive and selective glucose biosensors based on polypyrrole (PPy) nanofibers without using price-rising mediator or nanoparticles. The nanofibers were produced by chemical vapor polymerization of pyrrole on FeCl3 containing PAN nanofiber mats. Amperometric biosensors were constructed by entrapment of glucose oxidase on the nanofibers with the help of glutaraldehyde. The operational parameters such as pH, working potential, enzyme amount were optimized. For every biosensor sensitivity, linear range, limit of detection (LOD), and Michaelis-Menten constant values were determined and the stabilities of some of the sensors were tested. Our studies underlined the clear effect of enzyme content where the biosensors tend to show widened the linear detection range as the enzyme loadings increased +0.65V. PPy-NFs/GOx-1 biosensor showed good sensitivity (68.95 μA/mM.cm2) and LOD (7.8 μM) without any interference effect at +0.65V. On the other hand, when it was operated at −0.65V (oxygen consumption) the biosensor exhibited enhanced sensitivity of 116.42 μA/mM.cm2 with modest LOD and operational stability. Due to utilization of biocompatible, large surface area, nanoporous PPy nanofibers; an improved analytical performance was achieved with a very short response time, good stability and high selectivity, which make them feasible candidates for commercialization.