ABSTRACT Registration of the conductance after the end of the electrochemical polymerisation of 3-methylthiophene (PMT) indicated a large conductance increase at open circuit. Further in situ conductance measurements with the polymeric... more
ABSTRACT Registration of the conductance after the end of the electrochemical polymerisation of 3-methylthiophene (PMT) indicated a large conductance increase at open circuit. Further in situ conductance measurements with the polymeric film in Bu4NPF6/acetonitrile base solution provided direct evidence for that — after the oxidation of the film — the final achievement, the accomplishment of the state of high conduction is not necessarily coupled with current flow any more. The non-faradaic step which may explain this observation is described as a chemical reorganisation within the film, which involves the transformation of solvated polymer segments to a more conjugated, non-solvated form.
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Research Interests: Engineering, Materials Science, Chemistry, Inorganic Chemistry, Bioelectrochemistry, and 12 moreElectrochemistry, Conducting Polymers, Adsorption, Conducting Polymer, Physical sciences, Polypyrrole, Quartz crystal microbalance, CHEMICAL SCIENCES, Electrodes, Electrode, Redox, and electrochemical quartz crystal microbalance sensor
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Research Interests: Engineering, Materials Science, Electrochemistry, Morphology, Conducting Polymers, and 15 moreComparative Study, Doping, Polymer, Electrosynthesis, Conducting Polymer, Physical sciences, OR, Polythiophene, Conductance, CHEMICAL SCIENCES, Butyric Acid, Acetic Acid, Electrodes, Electrode, and Modified Electrode
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In this study vitamin B12 covered magnetite nanoparticles have been incorporated into a conducting polypyrrole. This polymer was electrochemically synthesized in the presence of the B12-coated magnetite. The adsorption of B12 was... more
In this study vitamin B12 covered magnetite nanoparticles have been incorporated into a conducting polypyrrole. This polymer was electrochemically synthesized in the presence of the B12-coated magnetite. The adsorption of B12 was demonstrated by the decrease in absorbance of the vitamin in the supernatant liquid after B12 has been in contact with magnetite sol overnight. The composition of the layers
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AbstractIn this study, we demonstrate that by directly employing single-walled carbon nanotube arrays (SWCNT-arrays)—grown on conductive substrates—as working electrodes, selective and uniform electrodeposition of a conducting polymer,... more
AbstractIn this study, we demonstrate that by directly employing single-walled carbon nanotube arrays (SWCNT-arrays)—grown on conductive substrates—as working electrodes, selective and uniform electrodeposition of a conducting polymer, namely poly(3-hexylthiophene), can be achieved on the surface of the nanotubes. The overall kinetic pattern of the electrodeposition was studied by separating the deposition charge from the one related to the redox transformation of the polymer film deposited during the precedent cycles. Both the structure and the electrochemical properties of the hybrid materials were studied as a function of the electrodeposition cycles, thus the amount of the formed polymer. The hybrids were characterized by electron microscopic (SEM, TEM) and vibrational spectroscopic (Raman spectroscopy) means. The obtained results were compared and contrasted with those gathered on macroscopic-sized multi-walled carbon nanotube array-based composites in our group recently. Overall, we conclude that electrochemical polymerization is an attractive tool to synthesize conducting polymer/SWCNT hybrid materials with controlled composition and morphology. Graphical abstractHighy organized nanostructures of conduction polymer/SWCNT array hybrids were obtained via electrodeposition
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Poly(3-octyl-thiophene) (POT) and polypyrrole (PPy) iron oxalate composites were synthesized through a post-polymerization oxidative treatment. The composite of the latter has been prepared also by electrochemical polymerization. The... more
Poly(3-octyl-thiophene) (POT) and polypyrrole (PPy) iron oxalate composites were synthesized through a post-polymerization oxidative treatment. The composite of the latter has been prepared also by electrochemical polymerization. The samples have been characterized by X-ray diffraction (XRD), impedance spectroscopy, scanning electron microscope (SEM) combined with energy dispersive X-ray (EDX) spectroscopy, Mössbauer spectroscopy, cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). In
Research Interests: Engineering, Materials Science, Chemistry, Cyclic Voltammetry, Impedance Spectroscopy, and 15 morePolymerization, Conducting Polymer, Dielectric Spectroscopy, Physical sciences, Polypyrrole, Iron, Quartz crystal microbalance, Energy Dispersive X-Ray Analysis, CHEMICAL SCIENCES, X ray diffraction, Scanning Electron Microscope, Layered Structure, Conductive Polymer, Oxalate, and Long-range Interaction
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New types of electroconducting conjugated polymer (ECP) based enzymatic and gas sensors were developed by using thick film technology. In order to prepare a stable polymeric film which is suitable for the enzyme immobilization and for gas... more
New types of electroconducting conjugated polymer (ECP) based enzymatic and gas sensors were developed by using thick film technology. In order to prepare a stable polymeric film which is suitable for the enzyme immobilization and for gas detection itself, a special conducting salt (sodium dodecyl sulfate, SDS) was used. This combination resulted in sensors with favorable properties, i.e., higher sensitivity and longer operation stability. In the case of the ECP based uric acid biosensor a new layout was developed for the measurement of the current difference between the polymer and the enzyme electrode by using two working electrodes identically prepared (sensor and polymer electrodes) at the same time in the same solution. The sensor gives an easily measurable stationary response in the physiological concentration range of uric acid. Using a similar electropolymerization method, a selective ECP based sensor was prepared as part of a sensor array for intelligent gas monitoring. The changes in conductivity of the polypyrrole film in the presence of different gases were registered. A reversible sensor response of about 30 % in saturated methanol=air mixture and 50 % at 1000 ppm ammonia in air was obtained at room temperature. For NH3 a linear response in the 40‐1000 ppm concentration range could be registered while almost no response was obtained for ethanol, NO and CO. The sensor proved to be insensitive for H2.
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As the number of the contributions to the topic is quasi-infinite compared to the length of this book, a restricted number of examples—selected subjectively—are presented in this chapter to demonstrate how in situ electrochemical methods... more
As the number of the contributions to the topic is quasi-infinite compared to the length of this book, a restricted number of examples—selected subjectively—are presented in this chapter to demonstrate how in situ electrochemical methods can give the answer to diverse questions, arisen in connection with either the electropolymerization or the redox switching process.
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As it follows from the previous chapter, electrochemistry is the basic tool to control both the synthesis and especially the redox switching between the states: the isolator/conductor behavior can be tuned through the level of oxidation... more
As it follows from the previous chapter, electrochemistry is the basic tool to control both the synthesis and especially the redox switching between the states: the isolator/conductor behavior can be tuned through the level of oxidation hence it regulates the number of the charge carriers. The electrochemical process results in color, mass, conductance, para/diamagnetic, volume and structural changes, as well as it provokes transport processes in the adjacent solution layer.
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The aim of each in situ electrochemical method is to monitor one of the above-presented consequences of the electrochemical process. The additional signal can be correlated with the perturbation on the same time scale, uncovering this way... more
The aim of each in situ electrochemical method is to monitor one of the above-presented consequences of the electrochemical process. The additional signal can be correlated with the perturbation on the same time scale, uncovering this way the relation between the electrochemical and the triggered secondary events. Thus, spectral modifications, mass, structural volume and conductivity changes—occurring in parallel with the electrochemical process—complete the information on the process by enlightening secondary effects of the electrochemical perturbation.
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During the last three and a half decades, a family of macromolecules, exhibiting a surprisingly new behavior, has been uncovered. This group of polymers may behave as isolators, however they are able to conduct electricity under... more
During the last three and a half decades, a family of macromolecules, exhibiting a surprisingly new behavior, has been uncovered. This group of polymers may behave as isolators, however they are able to conduct electricity under well-defined conditions. This ability can be tuned by their oxidation state. The background insuring opportunity for making them conductive is the conjugation along the polymer chain.
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A kutatas temaja olyan konjugalt polimereken alapulo osszetett anyagok előallitasa, jellemzese es alkalmazasi lehetősegeik feltarasa volt, melyek magneses, termoelektromos vagy fotokatalitikus sajatsagokat mutatnak. Megvalositottuk... more
A kutatas temaja olyan konjugalt polimereken alapulo osszetett anyagok előallitasa, jellemzese es alkalmazasi lehetősegeik feltarasa volt, melyek magneses, termoelektromos vagy fotokatalitikus sajatsagokat mutatnak. Megvalositottuk magnetit nanoreszecskek szerves kozegbe tortenő atvitelet, es igazoltuk a magnetit nanoreszecskek feluleten elhelyezkedő hidroxil- es a karbonsavval szubsztitualt tiofenek karboxil-csoportja kozotti kolcsonhatas kemiai jelleget. A magnetit nanoreszecskek feluleten megvalositott adszorpcioja utjan eredmenyesen epitettunk be polipirrol elektrodba B12 vitamint. Megvalositottuk titan-dioxid es szen nanocső kotegeknek vezető polimerekkel tortenő kombinalasat. Kiemelkedő termoelektromos sajatsaggal rendelkező 3-alkiltiofenek polimerjeit atkristalyositva – nemesfemek beepitese reven – nanoszalas kompozitokat alakitottunk ki. A mintakat atfogoan jellemeztuk az anyagtudomany teruleten altalanosan hasznalt technikak (rontgen-diffrakcio, spektroszkopiak, elektronmikroszkop, elektrokemiai nanogravimetria, vezetesmeres) alkalmazasaval. Az irodalomban elsőkent kidolgoztuk az in situ spektroelektrokemiai es impedanciameres szimultan alkalmazhatosagat, kimutattuk es ertelmeztuk a vezetes kialakulasanak az egyes tolteshordozokkal valo – valtozo – korrelaciojat. Felhivtuk a figyelmet az elektronegativ anionok jelenleteben tortenő elektrokemiai polimerizacio veszelyere, es korultekintő alkalmazasanak szuksegessegere. | During the project, conducting polymer based composites – exhibiting magnetic, thermoelectric or photocatalytic properties - have been synthesized. We realised the transfer of magnetic nanoparticles into organic media, and proved the chemical pattern of the interaction between the hydroxyl group on the surface of the magnetic nanoparticles and the carboxyl group of the acid substituted thiophenes. Exploiting the adsorption of vitamin B12 on the magnetite nanoparticles, its successful incorporation into polypyrrole has been achieved. Composites of conducting polymers with nanotube arrays of titanium dioxide and carbon have been also synthesized. Via re-crystallisation of poly(3-alkylthiophenes) – possessing extraordinary good thermoelectric property – nanofils of composites with noble metals have been prepared. The composites have been characterized widely with XRD, SEM – EDX, EQCM, ac conductance, as well as by diffuse reflection mode, UV-VIS absorption and FTIR – ATR mode spectroscopy. For the first time in the literature, we elaborated the application of in situ spectroelectrochemistry and in situ conductance in a hyphenated mode, and elucidated the background of differences in the correlation between the development of the conductance and the optically distinguishable charge carriers. We called the attention to the potential dangers arising during the electro-polymerisation in the presence of electronegative anions, and to the necessity of its careful consideration.
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Atmospheric dependent, gas sensitive resistors seem to be good candidates for detecting critical air pollution levels. Recently, a great progress has been made in the development of various sensor types, but less attention seems to be... more
Atmospheric dependent, gas sensitive resistors seem to be good candidates for detecting critical air pollution levels. Recently, a great progress has been made in the development of various sensor types, but less attention seems to be paid to the integration of sensor elements of different nature. The aim of this international project is to develop a smart hybrid gas multisensor module for environmental applications, i.e. by combining classical thickand thin-film elements with polymer-film based sensors and also a signal processing ASIC within a single package, which should be useful for all sensor types. The module should enable the multisensor operation as well, when connected to an intelligent signal-processing unit.
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A large number of studies have indicated recently that photosynthetic reaction center proteins (RC) bind successfully to nanostructures and their functional activity is largely retained. The major goal of current research is to find the... more
A large number of studies have indicated recently that photosynthetic reaction center proteins (RC) bind successfully to nanostructures and their functional activity is largely retained. The major goal of current research is to find the most efficient systems and conditions for the photoelectric energy conversion and for the stability of this bio‐nanocomposite. In our studies, we immobilized the RC protein on multiwalled carbon nanotubes (MWNT) through specific chemical binding to amine functional groups and through conducting polymer (poly(3‐thiophene acetic acid), PTAA). Both structural (TEM, AFM) and functional (absorption change and conductivity) measurements has shown that RCs could be bound effectively to functionalized CNTs. The kinetics of the light induced absorption change indicated that RCs were still active in the composite and there was an interaction between the protein cofactors and the CNTs. The light generated photocurrent was measured in an electrochemical cell wit...
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Elektronvezető polimer alapú összetett (kompozit) anyagok előállítása és tulajdonságaik tanulmányozása in situ kombinált elektrokémiai technikákkal = Preparation of electronically conducting polymer based composite materials and their characterization by in situ combined electrochemical techniquesmore
9 ABSTRACT: In this study, we investigated the impact of a molecular and 10 supramolecular structure of conducting polymers (CPs) on their thermo-11 electric properties. As a model system, poly(3-alkylthiophene)s (P3ATs) 12 with different... more
9 ABSTRACT: In this study, we investigated the impact of a molecular and 10 supramolecular structure of conducting polymers (CPs) on their thermo-11 electric properties. As a model system, poly(3-alkylthiophene)s (P3ATs) 12 with different side-chain lengths were prepared through oxidative chemical 13 polymerization and were recrystallized to a well-ordered lamellar structure, 14 resulting in one-dimensional self-assembled nanofibers (evidenced by 15 transmission electron microscopy, X-ray diffraction, and UV−vis spectro-16 scopic measurements). Thermoelectric characterization was performed at 17 different doping levels (precisely tuned by doping in the redox reaction with 18 Ag+ and Fe3+ cations), and the highly doped samples exhibited the best 19 performance for all studied polymers. By varying the length of the alkyl side 20 chain, the supramolecular structure and consequently the electronic 21 properties were varied. The highest electrical conductivity was measured 22 for poly(3-...
As it follows from the previous chapter, electrochemistry is the basic tool to control both the synthesis and especially the redox switching between the states: the isolator/conductor behavior can be tuned through the level of oxidation... more
As it follows from the previous chapter, electrochemistry is the basic tool to control both the synthesis and especially the redox switching between the states: the isolator/conductor behavior can be tuned through the level of oxidation hence it regulates the number of the charge carriers. The electrochemical process results in color, mass, conductance, para/diamagnetic, volume and structural changes, as well as it provokes transport processes in the adjacent solution layer.
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As the number of the contributions to the topic is quasi-infinite compared to the length of this book, a restricted number of examples—selected subjectively—are presented in this chapter to demonstrate how in situ electrochemical methods... more
As the number of the contributions to the topic is quasi-infinite compared to the length of this book, a restricted number of examples—selected subjectively—are presented in this chapter to demonstrate how in situ electrochemical methods can give the answer to diverse questions, arisen in connection with either the electropolymerization or the redox switching process.
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During the last three and a half decades, a family of macromolecules, exhibiting a surprisingly new behavior, has been uncovered. This group of polymers may behave as isolators, however they are able to conduct electricity under... more
During the last three and a half decades, a family of macromolecules, exhibiting a surprisingly new behavior, has been uncovered. This group of polymers may behave as isolators, however they are able to conduct electricity under well-defined conditions. This ability can be tuned by their oxidation state. The background insuring opportunity for making them conductive is the conjugation along the polymer chain.
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In this book, the advantages of in situ combined electrochemical techniques applied to conducting polymers, which enables the correlation of various additive features provoked by the electrochemical process, are summarized. The... more
In this book, the advantages of in situ combined electrochemical techniques applied to conducting polymers, which enables the correlation of various additive features provoked by the electrochemical process, are summarized. The presentation of coupled phenomena during the process is followed by a brief overview of in situ combined electrochemical techniques. These methods deliver extra information about the processes via additional aspects such as color or other spectral modifications, mass, structure, volume and conductivity changes, which occur in parallel with either the electropolymerization process or the redox transformation. Their relevance is demonstrated by a better understanding of conducting polymers through a selection of applications, where problems and answers attempted by the in situ combined methods are presented. Advantages of recent technical developments—which have led to the combination of two in situ methods, furnishing information from several aspects at the same time on the self-same polymer film by employing two in situ electrochemical techniques in a hyphenated mode—are also discussed.
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In this work a poly(3,4-ethylenedioxythiophene) (PEDOT)/iron oxalate composite was synthesized by electrochemical polymerization. The layer was deposited potentiostatically from the monomer-containing solution in the presence of iron(II)... more
In this work a poly(3,4-ethylenedioxythiophene) (PEDOT)/iron oxalate composite was synthesized by electrochemical polymerization. The layer was deposited potentiostatically from the monomer-containing solution in the presence of iron(II) oxalate. Similarly to the polypyrrole/iron oxalate electrode--presented in a recent paper--the layer gave a negative photocurrent, which depended on the oxygen concentration of the electrolyte. This cathodic photocurrent--taken as the differences between the values registered under illumination and in the dark at -750 mV potential on the cathodic part of the voltammetric cycles--confirmed the sensitivity of the PEDOT/iron oxalate electrode for dissolved oxygen. Stationary photocurrents were determined also from chronoamperometric measurements, and they exhibited a linear behaviour with the dissolved oxygen concentration to below 1 ppm. The photo-effect of the PEDOT/iron oxalate layer can be attributed to the excitation of the neutral form of the film.
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ABSTRACT New types of electroconducting conjugated polymer (ECP) based enzymatic and gas sensors were developed by using thick film technology. In order to prepare a stable polymeric film which is suitable for the enzyme immobilization... more
ABSTRACT New types of electroconducting conjugated polymer (ECP) based enzymatic and gas sensors were developed by using thick film technology. In order to prepare a stable polymeric film which is suitable for the enzyme immobilization and for gas detection itself, a special conducting salt (sodium dodecyl sulfate, SDS) was used. This combination resulted in sensors with favorable properties, i.e., higher sensitivity and longer operation stability. In the case of the ECP based uric acid biosensor a new layout was developed for the measurement of the current difference between the polymer and the enzyme electrode by using two working electrodes identically prepared (sensor and polymer electrodes) at the same time in the same solution. The sensor gives an easily measurable stationary response in the physiological concentration range of uric acid. Using a similar electropolymerization method, a selective ECP based sensor was prepared as part of a sensor array for intelligent gas monitoring. The changes in conductivity of the polypyrrole film in the presence of different gases were registered. A reversible sensor response of about 30 % in saturated methanol/air mixture and 50 % at 1000 ppm ammonia in air was obtained at room temperature. For NH3 a linear response in the 40–1000 ppm concentration range could be registered while almost no response was obtained for ethanol, NO and CO. The sensor proved to be insensitive for H2.