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Journal ArticleDOI

Conducting Polymers: Halogen Doped Polyacetylene.

05 Aug 1978-Journal of Chemical Physics (American Institute of PhysicsAIP)-Vol. 69, Iss: 11, pp 5098-5104
TL;DR: In this article, the electrical conductivity of the halogen doped transpolyacetylene system, (CH)x, was studied in terms of a model of the doping process based on charge transfer.
Abstract: A study of the electrical conductivity of the halogen doped transpolyacetylene system, (CH)x, is reported. When films of trans‐ (CH)x are exposed to chlorine, bromine, or iodine vapor, uptake of halogen occurs; and the conductivity increases markedly, over eleven orders of magnitude in the case of iodine. The behavior of the halogenated polyacetylene is like that of a series of semiconductors with activation energies which vary with halogen content. The results are discussed in terms of a model of the doping process based on charge transfer.
Citations
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TL;DR: The emeraldine base form of polyaniline, which consists of equal numbers of reduced and oxidized repeat units, is doped to the metallic conducting regime by aqueous 1 M HCl as mentioned in this paper.

1,813 citations

Journal ArticleDOI
TL;DR: The role of polymers as gas sensors, pH sensors, ion-selective sensors, humidity sensors, biosensor devices, etc., are reviewed and discussed in this article, and current trends in sensor research and also challenges in future sensor research are discussed.

1,126 citations


Cites background from "Conducting Polymers: Halogen Doped ..."

  • ...Exposure of this normally resistive polymer to iodine vapor altered the conductivity by up to 11 orders of magnitude [58,59]....

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  • ...[58] Chiang CK, Park YW, Heeger AJ, Shirakawa H, Louis EJ, MacDiarmid AG....

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Journal ArticleDOI
Guigang Zhang1, Mingwen Zhang1, Xinxin Ye1, Xiaoqing Qiu1, Sen Lin1, Xinchen Wang1 
TL;DR: The as-prepared iodine functionalized g-CN shows enhanced electronic and optical properties, as well as increased photocatalytic activities in an assay of hydrogen evolution.
Abstract: An optimized and general synthetic strategy based on in-situ iodine modifying of polymeric graphitic carbon nitride is discussed. The as-prepared iodine functionalized g-CN shows enhanced electronic and optical properties, as well as increased photocatalytic activities in an assay of hydrogen evolution.

981 citations

Journal ArticleDOI
23 Apr 2017-Polymers
TL;DR: The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties.
Abstract: Conducting polymers (CPs) have received much attention in both fundamental and practical studies because they have electrical and electrochemical properties similar to those of both traditional semiconductors and metals. CPs possess excellent characteristics such as mild synthesis and processing conditions, chemical and structural diversity, tunable conductivity, and structural flexibility. Advances in nanotechnology have allowed the fabrication of versatile CP nanomaterials with improved performance for various applications including electronics, optoelectronics, sensors, and energy devices. The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties. The size and morphology of the materials are also discussed as key parameters that affect their major properties. Finally, the latest trends in research on electrochemical capacitors and sensors are introduced through an in-depth discussion of the most remarkable studies reported since 2003.

624 citations

Journal ArticleDOI
TL;DR: In this paper, a facile synthesis of bromine doped graphitic carbon nitride (g-C 3 N 4 ) photocatalysts for hydrogen evolution with visible light irradiation is presented.
Abstract: Hydrogen production by semiconductor photocatalysis using abundant sunlight and water is an ideal method to address the globe energy and environment issues. Here, we present a facile synthesis of bromine doped graphitic carbon nitride (g-C 3 N 4 ) photocatalysts for hydrogen evolution with visible light irradiation. Bromine modification is shown to enhance the optical, conductive and photocatalytic properties of g-C 3 N 4 , while still keeping the poly-tri-s(triazine) core structure as the main building blocks of the materials. This modification method can be generally applicable to several precursors of g-C 3 N 4 , including urea, dicyandiamide, ammonium thiocyanide, and thiourea. The optimal sample CNU-Br 0.1 shows more than two times higher H 2 evolution rates than pure CNU sample under visible light irradiation, with high stability during the prolonged photocatalytic operation. Results also found that the photocatalytic O 2 evolution activity of CNU-Br 0.1 was promoted when the sample was subjected to surface kinetic promotion by loading with cobalt oxide as a cocatalyst. This study affords us a feasible modification pathway to rationally design and synthesize g-C 3 N 4 based photocatalysts for a variety of advanced applications, including CO 2 photofixation, organic photosynthesis and environmental remediation.

421 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a metal-to-insulator transition at dopant concentrations near 1% was shown for polyacetylene, a new class of conducting polymers in which the electrical conductivity can be systematically and continuously varied over a range of eleven orders of magnitude.
Abstract: Doped polyacetylene forms a new class of conducting polymers in which the electrical conductivity can be systematically and continuously varied over a range of eleven orders of magnitude. Transport studies and far-infrared transmission measurements imply a metal-to-insulator transition at dopant concentrations near 1%.

2,945 citations

Journal ArticleDOI
TL;DR: In this paper, the authors considered a model in which charge is transported via phonon-induced tunneling of electrons between localized states which are randomly distributed in energy and position, and obtained an electrical conductivity of the form
Abstract: By considering a model in which charge is transported via phonon-induced tunneling of electrons between localized states which are randomly distributed in energy and position, Mott has obtained an electrical conductivity of the form $\ensuremath{\sigma}\ensuremath{\propto}\mathrm{exp}[\ensuremath{-}{(\frac{\ensuremath{\lambda}{\ensuremath{\alpha}}^{3}}{{\ensuremath{\rho}}_{0}\mathrm{kT}})}^{\frac{1}{4}}]$. Here $T$ is the temperature of the system, ${\ensuremath{\rho}}_{0}$ is the density of states at the Fermi level, $\ensuremath{\lambda}$ is a dimensionless constant, and ${\ensuremath{\alpha}}^{\ensuremath{-}1}$ is the distance for exponential decay of the wave functions. We rederive these results, relating $\ensuremath{\lambda}$ to the critical density of a certain dimensionless percolation problem, and we estimate $\ensuremath{\lambda}$ to be approximately 16. The applicability of the model to experimental observations on amorphous Ge, Si, and C is discussed.

1,458 citations

Journal ArticleDOI
TL;DR: In this paper, thermal analysis and infrared spectroscopy of polyacetylene was used to investigate cis-trans isomerization, hydrogen migration accompanied with crosslinking reaction, and thermal decomposition.
Abstract: Thermal cis-trans isomerization and decomposition of polyacetylene film prepared with a Ti(OC4H9)4–Al(C2H5)3 (Al/Ti = 4) system were investigated under inert gas or in vacuum by means of thermal analysis and infrared spectroscopy. Thermograms of differential thermal analysis of cis-polyacetylene revealed the existence of two exothermic peaks at 145 and 325°C and one endothermic peak at 420°C which were assigned to cis-trans isomerization, hydrogen migration accompanied with crosslinking reaction, and thermal decomposition, respectively. The isomerization was followed by infrared spectroscopy over the temperature range 75–115°C. The reaction did not obey simple kinetics. The apparent activation energy for the cis-trans isomerization was 17.0 kcal/mole for the polymer containing 88% cis configuration and increased with increasing trans content up to 38.8 kcal/mole for 80% trans content.

280 citations