The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Panagiotis Lianos - One of the best experts on this subject based on the ideXlab platform.
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reduced graphene oxide polypyrrole pedot composite films as efficient pt free counter electrode for dye sensitized solar cells
Electrochimica Acta, 2015Co-Authors: Madeshwaran Sekkarapatti Ramasamy, Archontoula Nikolakapoulou, Dimitrios Raptis, Vassilios Dracopoulos, Georgios Paterakis, Panagiotis LianosAbstract:Abstract Moderately reduced graphene oxide/polypyrrole/PEDOT composite films have been fabricated via a three-step process. Graphene oxide/polypyrrole composites were first composed by in-situ polymerization. Uniform thin films of graphene oxide/polyryrrole were then deposited on transparent conductive electrodes and annealed at 300 °C to produce moderately reduced graphene oxide/polypyrrole composite films. Even though, at this temperature loss of polypyrrole begins due to calcination, the presence of polypyrrole facilitates uniform film formation and prepares it for the next step of conductive polymer deposition. Finally, poly(3,4 ethylenedioxythiophene), PEDOT, was deposited on the reduced graphene oxide/polypyrrole film by one-step electrodeposition and was employed as electrocatalyst on counter electrodes in dye-sensitized solar cells. Cells employing this composite electrocatalyst demonstrated power conversion efficiency of 7.1 %, which is comparable to that of Pt-based cells made under similar conditions. These findings support the idea of Pt-free solar cells.
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a quasi solid state dye sensitized solar cell made of polypyrrole counter electrodes
Electrochimica Acta, 2011Co-Authors: Theodoros Makris, Vassilios Dracopoulos, Thomas Stergiopoulos, Panagiotis LianosAbstract:Quasi-solid state dye-sensitized solar cells have been constructed using nanocrystalline titania, a Ureasil-based nanocomposite gel electrolyte and polypyrrole-functionalized counter electrode. Polypyrrole was synthesized by potentiostatic electrodeposition using pyrrole monomer as precursor by a simple procedure in aqueous solution. The thus obtained polypyrrole films were very robust. They were characterized by FE-SEM microscopy and electrochemical impedance spectroscopy and they were used for the construction of solar cells. The employment of polypyrrole electrocatalyst was judged satisfactory for the present application since it was only 30% less efficient than the corresponding counter electrodes functionalized with Pt.
Derek O Northwood - One of the best experts on this subject based on the ideXlab platform.
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an investigation into the effects of a nano thick gold interlayer on polypyrrole coatings on 316l stainless steel for the bipolar plates of pem fuel cells
Journal of Power Sources, 2008Co-Authors: Ya Wang, Derek O NorthwoodAbstract:Abstract Polypyrrole is one of the most important conductive polymers because it is easily oxidized, water soluble and commercially available. Also, polypyrrole coatings have potential applications in batteries, fuel cells, electrochemical sensors, anti-corrosion coatings and drug delivery systems. In this study, a very thin gold layer was first coated on SS316L, and then a polypyrrole coating was laid on top. The nucleation and growth mechanisms of polypyrrole on the gold-coated SS316L were studied by electrochemical nucleation and growth techniques. SEM was used to characterize the polypyrrole coating morphology. Potentiodynamic tests were performed to determine the corrosion parameters of the polypyrrole coatings. Potentiostatic tests of the coated SS316L were conducted in simulated anode and cathode environments of a PEM fuel cell. The simulated anode environment was at a potential of about −0.1 V versus SCE purged with H2 and the simulated cathode environment was at a potential of about 0.6 V versus SCE purged with O2. After coating with Au and polypyrrole, the polarization resistance of SS316L is increased about six times, and the corrosion current density is decreased about seven times, compared to the base SS316L. Also, our calculations show that the metal ion concentration in solution for the polypyrrole/Au/SS316L had met the target of 10 ppm after 5000 h fuel cell operation.
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an investigation into polypyrrole coated 316l stainless steel as a bipolar plate material for pem fuel cells
Journal of Power Sources, 2006Co-Authors: Yan Wang, Derek O NorthwoodAbstract:Increasing attention is being paid to the use of metallic materials as a replacement for non-porous graphite in bipolar plates (BPs) for polymer exchange membrane (PEM) fuel cells. The ideal BP material should demonstrate high values of electrical conductivity, thermal conductivity, corrosion resistance and compressive strength and low values of gas permeability and density. Although metallic materials demonstrate many of those properties, their corrosion resistance can be inadequate, which in turn can lead to unacceptable values of contact resistivity. In this study, polypyrrole was polymerized onto 316L stainless steel using galvanostatic and cyclic voltammometric methods. A dense coating of polypyrrole could be formed on SS316L using both electrochemical methods. The coatings had different morphologies. For galvanostatic coatings, the particle size increases with increasing applied current. For cyclic voltammometric coatings, the particle size increases with increasing the cycle number. The potentiodynamic tests show that the corrosion current density is decreased by about one order of magnitude and polarization resistance is increased by about one order of magnitude by coating with polypyrrole. Optical microscopy showed that there is less intergranular corrosion after coating with polypyrrole. Therefore, these dense polypyrrole coatings much improved the corrosion resistance of SS316L and the coated materials could possibly be used in polymer exchange membrane fuel cells (PEMFCs) as a bipolar plate material.
Vassilios Dracopoulos - One of the best experts on this subject based on the ideXlab platform.
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reduced graphene oxide polypyrrole pedot composite films as efficient pt free counter electrode for dye sensitized solar cells
Electrochimica Acta, 2015Co-Authors: Madeshwaran Sekkarapatti Ramasamy, Archontoula Nikolakapoulou, Dimitrios Raptis, Vassilios Dracopoulos, Georgios Paterakis, Panagiotis LianosAbstract:Abstract Moderately reduced graphene oxide/polypyrrole/PEDOT composite films have been fabricated via a three-step process. Graphene oxide/polypyrrole composites were first composed by in-situ polymerization. Uniform thin films of graphene oxide/polyryrrole were then deposited on transparent conductive electrodes and annealed at 300 °C to produce moderately reduced graphene oxide/polypyrrole composite films. Even though, at this temperature loss of polypyrrole begins due to calcination, the presence of polypyrrole facilitates uniform film formation and prepares it for the next step of conductive polymer deposition. Finally, poly(3,4 ethylenedioxythiophene), PEDOT, was deposited on the reduced graphene oxide/polypyrrole film by one-step electrodeposition and was employed as electrocatalyst on counter electrodes in dye-sensitized solar cells. Cells employing this composite electrocatalyst demonstrated power conversion efficiency of 7.1 %, which is comparable to that of Pt-based cells made under similar conditions. These findings support the idea of Pt-free solar cells.
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a quasi solid state dye sensitized solar cell made of polypyrrole counter electrodes
Electrochimica Acta, 2011Co-Authors: Theodoros Makris, Vassilios Dracopoulos, Thomas Stergiopoulos, Panagiotis LianosAbstract:Quasi-solid state dye-sensitized solar cells have been constructed using nanocrystalline titania, a Ureasil-based nanocomposite gel electrolyte and polypyrrole-functionalized counter electrode. Polypyrrole was synthesized by potentiostatic electrodeposition using pyrrole monomer as precursor by a simple procedure in aqueous solution. The thus obtained polypyrrole films were very robust. They were characterized by FE-SEM microscopy and electrochemical impedance spectroscopy and they were used for the construction of solar cells. The employment of polypyrrole electrocatalyst was judged satisfactory for the present application since it was only 30% less efficient than the corresponding counter electrodes functionalized with Pt.
Arumugam Manthiram - One of the best experts on this subject based on the ideXlab platform.
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core shell structured sulfur polypyrrole composite cathodes for lithium sulfur batteries
RSC Advances, 2012Co-Authors: Yongzhu Fu, Arumugam ManthiramAbstract:A sulfur-polypyrrole composite cathode with a core-shell structure consisting of spherical sulfur particles coated with polypyrrole has been developed. The conductive polypyrrole coating on the sulfur facilitates fast electron transport enabling the material with superior electrochemical stability, rate capability, and cyclability in lithium-sulfur batteries.
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orthorhombic bipyramidal sulfur coated with polypyrrole nanolayers as a cathode material for lithium sulfur batteries
Journal of Physical Chemistry C, 2012Co-Authors: Arumugam ManthiramAbstract:A sulfur–polypyrrole composite consisting of orthorhombic bipyramidal sulfur particles (63.3 wt %) coated with a polypyrrole nanolayer has been synthesized by a low-cost, scalable, environmentally benign process and investigated as a cathode material for Li-ion batteries. Cathodes containing the sulfur–polypyrrole composite have been evaluated in half cells by cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The sulfur–polypyrrole composite cathode shows better electrochemical stability, cyclability, and rate capability than pristine sulfur as the polypyrrole coating acts as a conductive matrix for electron transfer while prohibiting lithium polysulfide dissolution. At C/5 rate, the sulfur–polypyrrole composite cathode exhibits ∼200 mAh/g higher capacity than the pristine sulfur after 50 cycles. At C/2 and 1C rates, the composite shows significantly better capacity retention than the pristine sulfur over 100 cycles.
Yibing Xie - One of the best experts on this subject based on the ideXlab platform.
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electrochemical capacitance of polypyrrole titanium nitride and polypyrrole titania nanotube hybrids
New Journal of Chemistry, 2014Co-Authors: Yibing Xie, Chi Xia, Wei Wang, Fang TianAbstract:Both polypyrrole–titanium nitride (PPy–TiN) and polypyrrole–titania (PPy–TiO2) nanotube hybrids have been prepared by incorporating electroactive polypyrrole into well-aligned titanium nitride and titania nanotube arrays through a normal pulse voltammetry deposition process. Microstructure characterization shows that the Polypyrroles have been fully coated on the titanium nitride and titania nanotube arrays to form coaxial heterogenous nanohybrids. The galvanostatic charge–discharge measurements indicate that the PPy–TiN and PPy–TiO2 nanotube hybrids have specific capacitances of 1265 and 382 F g−1 at a current density of 0.6 A g−1. Both nanotube hybrids have similar cyclability, exhibiting stable capacitances of 459 and 72 F g−1 after 2000 cycles at a high current density of 15 A g−1. The highly conductive titanium nitride substrate can promote the electrochemical capacitance of polypyrrole more significantly, as compared to the titania semiconductor, contributing to a higher supercapacitance performance of PPy–TiN. This indicates that PPy–TiN nanotube hybrids can be more suitable to act as supercapacitor electrode materials.
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electrochemical capacitance performance of polypyrrole titania nanotube hybrid
Journal of Solid State Electrochemistry, 2012Co-Authors: Yibing XieAbstract:In this study, the polypyrrole–titania nanotube hybrid has been synthesized for an electrochemical supercapacitor application. The highly ordered and independent titania nanotube array is fabricated by an electro-oxidation of titanium sheet through an electrochemical anodization process in an aqueous solution containing ammonium fluoride, phosphoric acid and ethylene glycol. The polypyrrole–titania nanotube hybrid is then prepared by electrodepositing the conducting polypyrrole into well-aligned titania nanotubes through a normal pulse voltammetry deposition process in an organic acetonitrile solution containing pyrrole monomer and lithium perchlorate. The morphology and microstructure of polypyrrole–titania nanotube hybrid are characterized by scanning electron microscopy, infrared spectroscopy and Raman spectroscopy. The electrochemical capacitance performance is determined by cyclic voltammetry and charge/discharge measurement. It indicates that the polypyrrole film can been uniformly deposited on both surfaces of titania nanotube walls, demonstrating a heterogeneous coaxial nanotube structure. The specific capacitance of polypyrrole–titania nanotube hybrid is determined to be 179 F g−1 based on the polypyrrole mass. The specific energy and specific power are 7.8 Wh kg−1 and 2.8 kW kg−1 at a constant charge/discharge current of 1.85 mA cm−2, respectively. The retained specific capacitance still keeps 85% of the initial capacity even after 200 cycle numbers. This result demonstrates the satisfying stability and durability of PPy–TiO2 nanotube hybrid electrode in a cyclic charge/discharge process. Such a composite electrode material with highly ordered and coaxial nanotube hybrid structure can contribute high energy storage for supercapacitor applications.