Bhavna H. Meshram; Subhash B. Kondawar
Abstract
Fabrication of nanocomposite film of electrically conducting polypyrrole (PPy) and functionalized multi-walled carbon nanotubes (MWCNTs) on a stainless steel electrode by electro-deposition method and immobilization of urease onto the nanocomposite film to obtain a nanobiocomposite electrode as a sensitive ...
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Fabrication of nanocomposite film of electrically conducting polypyrrole (PPy) and functionalized multi-walled carbon nanotubes (MWCNTs) on a stainless steel electrode by electro-deposition method and immobilization of urease onto the nanocomposite film to obtain a nanobiocomposite electrode as a sensitive electrochemical urease biosensor is reported. Cross-linking by glutaraldehyde (0.1%) method for the immobilization of urease (2 mg/mL) in a phosphate buffer solution of 0.1 molarity at a pH of 7.0 was used. The Characterization of the nanocomposite and nanobiocomposite film thus obtained was done by Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS). The increased size of the Cyclic voltammogram and shifting of anionic peaks towards the lower voltage indicates the incorporation of MWCNTs into the growing film during the electro-deposition of PPy on electrode. Reduction of the oxidation potential due to MWCNTs leads to lowering of potential for the electro-catalytic reduction of urea. The incorporation of functionalized MWCNT also made possible increased amount of enzyme concentration, an extended lifetime, long time stability and improved response times of the enzyme electrode. This modified nanobiocomposite electrode showed a good linear response to the urea concentration change in the range of 10 mM to 50 mM. The results obtained from Michaelis–Menten constant K´m, maximum current (Imax), detection limit, sensitivity, response time and shelf-life of electrochemical biosensor indicating good sensing for urea detection.
Ritu P. Mahore; Devendra K. Burghate; Subhash B. Kondawar; Ashish P.Mahajan; Deoram V. Nandanwar
Abstract
Due to the ever growing demand of energy for various applications attention of researchers is aroused by Supercapacitors due to its superior power, energy density and cyclic life. Electrode material mainly determines the performance of Supercapacitors. Conducting polymers, metal oxides and carbon based ...
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Due to the ever growing demand of energy for various applications attention of researchers is aroused by Supercapacitors due to its superior power, energy density and cyclic life. Electrode material mainly determines the performance of Supercapacitors. Conducting polymers, metal oxides and carbon based materials are mainly used as electrode materials in Supercapacitors. Among these three categories of materials, Conducting polymers and metal oxides shows pseudo-capacitance. This paper reported the synthesis of Pure Polypyrrole (PPy) and Polypyrrole/Manganese dioxide (PPy/MnO2) nanocomposites by in-situ chemical oxidative polymerization. The synthesized materials were tested as potential candidates for the electrodes of supercapacitor. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) revealed that nanoparticles of MnO2 are well incorporated into PPy matrix. Cyclic Voltammetry (CV) indicated that PPy/MnO2 nanocomposites have an ideal capacitive behaviour and an excellent cyclibility. Electrochemical impedance spectroscopy (EIS) and Galvanostatic charge-discharge (GCD) measurements proved that nanocomposite electrode with 10% MnO2 composition showed the smallest charge transfer resistance and highest specific capacitance compared to other compositions. The electrochemical studies of PPy/MnO2 nanocomposites showed that PPy/MnO2 nanocomposites are suitable advanced materials for electrodes of the supercapacitors. Copyright © 2018 VBRI Press.
Hemlata J. Sharma; Bhaskar M. Bahirwar; Subhash B. Kondawar
Abstract
Metal oxide nanofibers showed keen interest in chemical gas sensing due to their unique chemical and electrical properties at operating temperature more than 200 o C. Their sensitivity can be improved at low operating temperature closed to room temperature by using conducting polymers. In this paper, ...
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Metal oxide nanofibers showed keen interest in chemical gas sensing due to their unique chemical and electrical properties at operating temperature more than 200 o C. Their sensitivity can be improved at low operating temperature closed to room temperature by using conducting polymers. In this paper, Al doped tin oxide/polyaniline composite nanofibers detected H2 molecules at room temperature. A simple versatile electrospinning technique is used for the fabrication of Aluminium (Al) doped (tin oxide) SnO2 nanofibers and polyaniline was encapsulated using chemical oxidative polymerization (COP) of aniline monomer using ammonium persulfate as redox initiator. The structure and morphology of Al-doped SnO2/PANI composite nanofibers were investigated by SEM-EDX, UV-VIS and XRD spectroscopy. Structural changes of SnO2/PANI crystal due to the incorporation of Al 3+ ions have been explained. Al-doped SnO2/PANI composite nanofiber is very much selective towards H2 gas molecules in terms of high sensitivity, rapid response and recovery around room temperature compared to that of Al-doped SnO2. The present sensing mechanism systematically explained the existence of PN junction which is formed by p-type and n-type semiconductors in Al-doped SnO2/PANI hybrid composite material.
Milind D. Deshpande; Subhash B. Kondawar
Abstract
In this paper, we report the influence of functionalized multi-walled carbon nanotubes (MWCNTs) on transport properties of conducting polymers polythiophene (PTH) and polyaniline (PANI). Nanocomposites based on multi-walled carbon nanotubes were synthesized by in-situ oxidative polymerization of thiophene/aniline ...
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In this paper, we report the influence of functionalized multi-walled carbon nanotubes (MWCNTs) on transport properties of conducting polymers polythiophene (PTH) and polyaniline (PANI). Nanocomposites based on multi-walled carbon nanotubes were synthesized by in-situ oxidative polymerization of thiophene/aniline monomer in the presence of functionalized MWCNTs. These nanocomposites have been characterized by SEM, UV-VIS, FTIR, and XRD to study the effect of incorporation of MWCNTs on the morphology, structure and crystalline of the conducting polymers. Nanocomposites have shown high electrical conductivity compared to that of pure PTH/PANI. The enhancement in conductivity of the nanocomposites is due to the charge transfer effect from the quinoid rings of the PTH/PANI to the MWCNT. The effect of MWCNT on the transport properties of PTH and PANI was systematically studied and compared in terms of transport parameters. Charge localization length and most probable hopping distance were found to be decreased with wt % of CNT, whereas the charge hopping energy was found to be increased in nanocomposites. The improved transport properties of both the types of nanocomposites due to incorporation of CNT in conducting polymer matrix can be utilized for solar cells, capacitors, electronic devices as well as chemical sensors.
Pravin S. More; Dattatray J. Late; Subhash B. Kondawar
Abstract
We report investigations on resistive material SnO2: Cu (9 wt. %) evaluated and optimized for the application of gas sensor. SnO2: Cu has been thoroughly characterized by using X-ray photoelectron spectroscopy (XPS). The deconvolution of XPS spectra confirms the existing surface reactive species in the ...
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We report investigations on resistive material SnO2: Cu (9 wt. %) evaluated and optimized for the application of gas sensor. SnO2: Cu has been thoroughly characterized by using X-ray photoelectron spectroscopy (XPS). The deconvolution of XPS spectra confirms the existing surface reactive species in the form of states of the metal orbital and the presence of multiple pathways for the detection of CO vis-à-vis sintering temperature effect. Enhanced CO pickup at the sintering temperature of 650 0 C (wide range and low sensitivity) and 750 0 C (short range and high sensitivity) has been observed. The CO sensing and XPS data correlates well along with the nonconventional use of variation in average XPS background intensity of general scan seems to be related to optimized sensitivity conditions of various gases.
Suyog M. Pethe; Subhash B. Kondawar
Abstract
One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from high surface area to volume ratio. Conducting polyaniline nanofibers can be synthesized by various methods. In this paper, we report the ...
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One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from high surface area to volume ratio. Conducting polyaniline nanofibers can be synthesized by various methods. In this paper, we report the preparation of polyaniline nanofibers with an average diameter of 40–70 nm by two different simple approach rapid mixing and interfacial polymerization. The key to producing polyaniline nanofibers is to suppress secondary growth. Based on this, interfacial polymerization and rapidly mixed reactions have been developed that can readily produce nanofibers by slightly modifying the conventional chemical synthesis of polyaniline without the need for any template or structural directing agent. Synthesized polyaniline (PANI) nanofibers were characterized by FTIR spectroscopy, X-ray diffraction, transmission electron microscopy for their structural and UV-Vis absorption spectroscopy for optical properties. Direct and indirect transition energy gaps were determined from their Tauc plots. The absorption spectra show a linear fit for the transition. Electrical properties of the synthesized polyaniline nanofibers have been studied and the Arrhenius plots of electrical conductivity for the samples synthesized by rapid mixing and interfacial polymerization method show an approximate equal in their activation energy. The results obtained from optical and electrical properties are well compared, correlated and explained with respect to interfacial and rapid mixing polymerization techniques.
Subhash B. Kondawar; Pallavi T. Patil; Shikha P. Agrawal
Abstract
Zinc oxide (ZnO) nanoparticles were synthesized by simple route of sol-gel method and nanofibers of polyaniline (PANI) and PANI/ZnO nanocomposites prepared using the electrospinning technique. Electrospun nanofibers of PANI and PANI/ZnO nanocomposites were collected on aluminum substrate for characterization ...
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Zinc oxide (ZnO) nanoparticles were synthesized by simple route of sol-gel method and nanofibers of polyaniline (PANI) and PANI/ZnO nanocomposites prepared using the electrospinning technique. Electrospun nanofibers of PANI and PANI/ZnO nanocomposites were collected on aluminum substrate for characterization and on Cu-interdigited electrodes to prepare chemiresistor sensor. Electrospun nanofibers of PANI and PANI/ZnO nanocomposites have been characterized by UV-Visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). UV-Visible spectra of nanofibers of PANI/ZnO nanocomposites show hypsochromic shift as that of PANI and some interaction due to ZnO in PANI matrix. The observed changes in the FTIR spectra of the fibers of PANI/ZnO nanocomposites are assosciated with the formation of H-bonding between ZnO and the N-H group present in the PANI chains. X-ray diffraction patterns exhibits hexagonal wurtzite structure of ZnO and broad amorphous peaks of PANI. Heterogeneous structures with fibrous characteristics of diameter less than 300nm of PANI/ZnO nanocomposites are identified in the SEM images. The electrical properties were characterized by I-V characteristic measurements. The changes in resistance of the chemiresistor sensor were utilized for detection of HCl and NH3 chemical vapour at room temperature. The resistance of the sensors was found to be decreased when they were exposed to HCl vapours whereas the resistance of the sensors was found to be increased when they were exposed to NH3 vapours. It was observed that PANI/ZnO nanocomposite sensor shows a high response and sensitivity with good repeatability as compared to that of pure PANI. Sensitivity result shows that PANI/ZnO nanocomposite is highly sensitive to chemical vapours even at room temperature and at very low concentration.
Ritu P. Mahore; Devendra K. Burghate; Subhash B. Kondawar
Abstract
Supercapacitors are recognized as one of the most promising energy storage devices for a wide range of civilian and military applications in electric vehicles, uninterruptible power supplies. Conducting polymer nanocomposites are new functional materials suitable for supercapacitors due to synergistic ...
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Supercapacitors are recognized as one of the most promising energy storage devices for a wide range of civilian and military applications in electric vehicles, uninterruptible power supplies. Conducting polymer nanocomposites are new functional materials suitable for supercapacitors due to synergistic effect of individual components. In present work, polypyrrole/CNT nanocomposites have been prepared by an in-situ chemical polymerization method and studied for supercapacitor. CNTs were well functionalized using 3:1 ratio of H2SO4 and HNO3 before polymerizing the pyrrole. Analytical techniques such as SEM, UV-VIS and FTIR were used to characterize the synthesized materials. The SEM images reveal that the materials have rough and granular morphology. The composites showed good interaction based on the shift to longer wavelengths in the electronic transition, indicating the interaction between PPy and functionalized CNTs as observed in their UV-VIS and FTIR spectra. The electrochemical performance was evaluated by using cyclic voltammetry (CV) in 1M Na2SO4 electrolyte and specific capacitance was obtained at 0.5 V/s for pure polypyrrole and PPy/CNT nanocomposites. Nanocomposite showed the enhanced electrochemical performance as compared to that of pure polypyrrole. The specific capacitance obtained at the scan rate 0.5V/s was found to be 0.825 F/cm -2 for pure polypyrrole and 1.0619 F/cm -2 for PPy/CNT nanocomposite material respectively, indicates that PPy/CNT nanocomposite is suitable material as electrode for supercapacitor as compoared to pure polypyrrole.
Subhash B. Kondawar; Suyog M. Pethe
Abstract
Intrinsically conducting polymers have been extensively studied due to their fascinating electronic properties and potential applications. One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from ...
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Intrinsically conducting polymers have been extensively studied due to their fascinating electronic properties and potential applications. One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from high surface area to volume ratio. In this paper, we report the synthesis of nanofibers of polyaniline and its substitute derivates and their comparative study in respect of electrical conductivity. Nanofibers of doped polyaniline (PANI), poly(o-methoxyaniline) (POMXA) and poly(o-methylaniline) (POMLA) were synthesized without need of any templates by interfacial polymerization. SEM, TEM, FTIR, UV-VIS and XRD were used to characterize the synthesized conducting polymeric materials. The average diameters of the synthesized nanofibers of conducting polymeric materials were in the range of 70-120 nm. The electrical conductivity was found to be in the range of 0.3 - 1.0 S/cm following the order as POMXA < POMLA < PANI which was found to be closely related to the size dependent electrical properties of the nanofibers. Optical band gap of these polymers was evaluated from UV–VIS absorption studies. Direct and indirect transition energy band gaps were determined from Tauc’s plots. Interfacial polymerization was shown to be readily scalable to produce bulk quantities of nanofibers of substitute derivative of polyaniline.
Subhash B. Kondawar; Arti I. Nandapure; Bharti I. Nandapure
Abstract
Nanocrystalline nickel ferrite (NiFe2O4) powder of crystallite size ~20 nm was synthesized by refluxing method. Electrically conductive polyaniline-nickel ferrite (PANI/NiFe2O4) nanocomposites have been synthesized by an in-situ polymerization of aniline monomer in the presence of as-prepared NiFe2O4 ...
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Nanocrystalline nickel ferrite (NiFe2O4) powder of crystallite size ~20 nm was synthesized by refluxing method. Electrically conductive polyaniline-nickel ferrite (PANI/NiFe2O4) nanocomposites have been synthesized by an in-situ polymerization of aniline monomer in the presence of as-prepared NiFe2O4 in different weight percentage (5%, 10%, and 15%). These nanocomposites were subsequently characterized for morphological, crystalline, structural, electrical and magnetic properties by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Four Probe Resistivity (FPR) and Vibrating Sample Magnetometer (VSM). Existence of NiFe2O4 in the nanocomposites was confirmed by XRD, FTIR and TEM analysis. The change in morphology with crystallite size ? 50 nm was observed for the nanocomposites clearly indicate the coating of PANI on NiFe2O4 . Nanocomposites showed increase in saturation magnetization as compared to that of PANI and increase in electrical conductivity as compared to that of NiFe2O4 indicating the synergistic effect of individual components. The saturation magnetization drastically increased as nickel ferrite content changed from 5 to 15% in nanocomposites. The conductivity of nanocomposites increased with temperature, exhibiting typical semiconductor behavior. The nanocomposites show semiconducting and ferromagnetic behaviour. The electrical conductivity of nanocomposites decreased from 1.089 to 0.268 S/cm, but saturation magnetization increased from 0.97 to 2.803 emu/g, when ferrite content changed from 5 to 15 wt%, indicates such nanocomposites are good for electromagnetic devices.
Subhash B. Kondawar; A. D. Dahegaonkar; V. A. Tabhane; D. V. Nandanwar
Abstract
With more than 100 million tonnes of fly ash produced in India, use of fly ash for the preparation of polyaniline – fly ash composites will in no way help in its bulk utilization. Still the authors have made an effort towards the better utility of fly ash by synthesizing polyaniline –fly ...
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With more than 100 million tonnes of fly ash produced in India, use of fly ash for the preparation of polyaniline – fly ash composites will in no way help in its bulk utilization. Still the authors have made an effort towards the better utility of fly ash by synthesizing polyaniline –fly ash composites for electronic devices where the requirement of dielectric materials with good electrical conductivity. There is great challenge to use the waste of thermal power stations in the form of fly ash as reinforcement for the conducting polymers to be good dielectric materials. In this paper, we report the use of fly ash to prepare conducting polymer composite materials. In-situ polymerization of aniline was carried out in the presence of fly ash (FA) to synthesize conducting polyaniline–fly ash composites (PANI-FA) by chemical oxidation method. The PANI-FA composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt %) of fly ash in conducting polymer matrix. The surface morphology of these composites was studied by scanning electron microscopy (SEM). These composites were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), Fourier Transform Infra-Red (FTIR) Spectroscopy to investigate surface morphology and structure of the composites. Thermal and frequency dependence dielectric properties of all the synthesized composites have been studied with the help of impedance analyzer. By incorporating fly ash into conducting polymers, dielectric constant of the composites was found to be improved as compared to that of pure conducting polymers. It was also noticed that the dielectric constant of all the composites found to be decreased with increasing frequency but increased with increasing temperature. The results obtained for these composites are of greater scientific and technological interest for good quality capacitors.
Subhash B. Kondawar; Smita A. Acharya; Sanjay R. Dhakate
Abstract
ZnO in different nanostructures were synthesized by microwave assisted hydrothermal route. Different experimental conditions such as microwave irradiation power, exposure time have been investigated to reveal the process of formation of the ZnO nanostructures. It was revealed that the microwave exposure ...
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ZnO in different nanostructures were synthesized by microwave assisted hydrothermal route. Different experimental conditions such as microwave irradiation power, exposure time have been investigated to reveal the process of formation of the ZnO nanostructures. It was revealed that the microwave exposure time plays a vital role in determining the diameter of the rods. The interaction of microwaves with the growth units of ZnO was systematically investigated to explain formation of different structural geometry of ZnO on nanoscale. ZnO nanostructures consisted of flower-like, sword-like, needle-like and rods-like structures were prepared by microwave assisted hydrothermal process at different conditions of microwave power and irradiation time. The ZnO nanostructures are in hexagonal phase. It is considered that microwave can interact with growth units of ZnO to generate active centers on the surface of ZnO nuclei so that needle-like ZnO rods are created on those sites, resulting in the formation of the flower-like ZnO nanostructures. Polyaniline - ZnO nanocomposites (PZ) in various weight % of nanostructure ZnO were synthesized by the chemical oxidation method in sulphuric acid medium using ammonium persulphate as oxidant at 276K. The synthesized polymer nanocomposites were characterized by XRD, FTIR and UV-VIS spectroscopy.
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