Polypyrrole Nanotubes and Their Carbonized Analogs: Synthesis, Characterization, Gas Sensing Properties.

Jitka Kopecká,Dušan Kopecký,Miroslav Mrlík,Zuzana Morávková,Jaroslav Stejskal,Patrycja Bober,Miroslava Trchová,Robert Olejník,Jan Prokeš,Martin Vrňata

doi:10.3390/s16111917

Abstract

Polypyrrole (PPy) in globular form and as nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in the absence and presence of methyl orange, respectively. They were subsequently converted to nitrogen-containing carbons at 650 °C in an inert atmosphere. The course of carbonization was followed by thermogravimetric analysis and the accompanying changes in molecular structure by Fourier Transform Infrared and Raman spectroscopies. Both the original and carbonized materials have been tested in sensing of polar and non-polar organic vapors. The resistivity of sensing element using globular PPy was too high and only nanotubular PPy could be used. The sensitivity of the PPy nanotubes to ethanol vapors was nearly on the same level as that of their carbonized analogs (i.e., ~18% and 24%, respectively). Surprisingly, there was a high sensitivity of PPy nanotubes to the n-heptane vapors (~110%), while that of their carbonized analog remained at ~20%. The recovery process was significantly faster for carbonized PPy nanotubes (in order of seconds) compared with 10 s of seconds for original nanotubes, respectively, due to higher specific surface area after carbonization.

Highlights

Since carbon nanotubes (CNTs) appeared to be very attractive for volatile organic compounds detection, many research groups focused on the development of the various sensors [1,2,3,4,5,6,7]
Its carbonization proved of that theyields morphology is retained whenmorphology this process [21]
Its carbonization proved that the morphology is retained when this process is carried out in an inert in a dramatic(Figure change1ainright)

Summary

Introduction

Since carbon nanotubes (CNTs) appeared to be very attractive for volatile organic compounds detection, many research groups focused on the development of the various sensors [1,2,3,4,5,6,7]. The functionalized nanotubes exhibit higher molecular reactivity, the development of new carbonaceous materials with controlled morphology is a promising research direction in sensing. Polypyrrole (PPy) is known to be a promising material for gas sensors detecting vapors of organic solvents [15]. Another interesting aspect is represented by the possibility to study properties of PPy-based sensors by impedance spectroscopy [16]

Methods

Results

Conclusion