Recent advances in synthesis, physical properties and applications of conducting polymer nanotubes and nanofibers

Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their nanoscaled size: high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity. Template methods are emerging for a sort of facile, efficient, and highly controllable synthesis of conducting polymer nanostructures. This paper reviews template synthesis routes for conducting polymer nanostructures, including soft and hard template methods, as well as its mechanisms. The application of conducting polymer mesostructures in energy storage devices, such as supercapacitors and rechargeable batteries, are discussed.

Conducting Polymer Nanostructures: Template Synthesis and Applications in Energy Storage

The Seebeck coefficient, S, and the electrical conductivity, σ, of electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires and thin films are reported. PEDOT nanowires were prepared by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) in aqueous LiClO4 within a template prepared using the lithographically patterned nanowire electrodeposition (LPNE) process. These nanowires were 40−90 nm in thickness, 150−580 nm in width, and 200 μm in length. σ and S were measured from 190 K to 310 K by fabricating heaters and thermocouples on top of arrays of 750 PEDOT nanowires. Such PEDOT nanowire arrays consistently produced S values that were higher than those for PEDOT films: up to −122 μV/K (310 K) for nanowires and up to −57 μV/K (310 K) for films. The sample-to-sample variation in S for 14 samples of PEDOT nanowires and films, across a wide range of critical dimensions, is fully explained by variations in the carrier concentrations in accordance with the Mott equation. In spite of their higher |S|...

Enhanced Thermoelectric Metrics in Ultra-long Electrodeposited PEDOT Nanowires

To meet the ever-increasing requirements for the next generation of sustainable and versatile energy-related devices, conjugated polymers, which have potential advantages over small molecules and inorganic materials, are among the most promising types of green candidates. The properties of conjugated polymers can be tuned through modification of the structure and incorporation of different functional moieties. In addition, superior performances can be achieved as a result of the advantages of nanostructures, such as their large surface areas and the shortened pathways for charge transfer. Therefore, nanostructured conjugated polymers with different properties can be obtained to be applied in different energy-related organic devices. This review focuses on the application and performance of the recently reported nanostructured conjugated polymers for high-performance devices, including rechargeable lithium batteries, microbial fuel cells (MFCs), thermoelectric generators, and photocatalytic systems. The design strategies, reaction mechanisms, advantages, and limitations of nanostructured conjugated polymers are further discussed in each section. Finally, possible routes to improve the performances of the current systems are also included in the conclusion.

Nanostructured Conjugated Polymers for Energy‐Related Applications beyond Solar Cells

The d.c. conductivity and the electric a.c. response from 100 Hz up to 40 MHz of poly(3n-decylpyrrole) were measured in the 80-330 K interval to characterize the charge transport behaviour of the system. The d.c. conductivity well fitted the variable range hopping model, and the loss factor, after having deducted the d.c. contribution, showed a relaxation peak when the conductivity versus frequency started to rise. The strength of this relaxation increased with temperature and became too large to be related to a dipolar relaxation; moreover, the temperature dependence of the loss peak frequency and d.c. conductivity coincided. The observed relaxation was attributed to the hopping charge transport, as further confirmed by the temperature behaviour of the relaxation strength and by the frequency dependence of the exponents of the power law which locally approximate the conductivity behaviour. As the activation energy of the d.c. conductivity differed from the frequency of the loss peak, the theoretical prediction concerning the selfsimilarity of the a.c. conductivity was roughly verified.

http://iopscience.iop.org/article/10.1088/0953-8984/10/25/011/pdf

Dielectric response analysis of a conducting polymer dominated by the hopping charge transport

We present results of high-pressure--low-temperature studies of template synthesized polypyrrole. Thermopower measurements at ambient pressure show a linear temperature dependence, which supports the intrinsic metallic character of the samples. The dc conductivity follows the typical variable-range-hopping behavior at low temperatures. The application of pressure results in an increasing localization length and an enhancement of the conductivity, especially at very low temperatures. The comparison with bulk samples of polypyrrole suggests that the template synthesis increases the localization length of the charge carriers, which in turn results in an increase of the dc electrical conductivity. \textcopyright{} 1996 The American Physical Society.

S.T. Ting

Papers

Thermopower and high-pressure electrical conductivity measurements of template synthesized polypyrrole.

High-pressure low-temperature electrical properties of polypyrrole doped with p-toluenesulfonate