Study of the primary sensitivity of polypyrrole/r-Fe2O3 to toxic gases
Introduction
In order to prevent human from being harmed by toxic gas and to protect the environment, the detection of toxic gas has become increasingly important. The sensing materials, which are inorganic or organic, have been studied widely [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]. But both of them have particular advantage and drawbacks. Though inorganic semiconductors, such as SnO2, Fe2O3, and ZnO, either undoped or doped have been studied extensively [1], [2], [3], [4], [5], [6] and have emerged as economical sensors for monitoring toxic gases, the disadvantages of semiconductor oxide sensors are their high operating temperature (350–450 °C) [15], [16], which increases power consumption, reduces sensor life, and limits the portability. Several organic semiconductors, such as polypyrrole, polyaniline, polythiophere, polyacetylene, etc. also have gas sensitivity at normal temperature [7], [8], [9], [10], [11], [12], [13], [14]. Polypyrrole is the most studied among these, but the self-limitations reduce the application largely. Because PPy is sensitivity to electrochemical and chemical degradation and the conductivity exhibits a long-term irreversible decay due to the irreversible attack of oxygen present in the ambient, and the long response time due to the highly ordered structure [17].
To prepare the optimized properties materials, organic–inorganic sensing hybrids have been developed [18], [19], considering which can complement the characteristics of pure inorganic and organic materials. The relating studies for gas sensors are few. Benjamin et al. [20] reported the polypyrrole/SnO2 had sensitivity to organic vapors at room temperature. Suri et al. [21] studied the pressure and humidity sensitivity of polypyrrole/iron oxide. These types of hybrid materials have been shown to possess small grain size and high stability in air [22], [23]. Nardis et al. [24] reported that cobalt porphyrin/tin dioxide had superior selectivity to methanol vapor than to CO.
In this paper, we prepared polypyrrole (PPy) by chemical oxidation and PPy/r-Fe2O3 by simultaneously gelling and polymerization. Methoxy ethanol was used as solvent and Fe(NO3)3·9H2O as oxidant in the two reactions. The samples were characterized by FTIR, XRD, TG-DTA, SEM, and HRTEM, and the gas sensitivity of them was then studied. To the best of our knowledge it is the first time to study the gas sensitivity of PPy/r-Fe2O3 to toxic gases, and for comparison the gas sensitivity of PPy was also studied at the same condition.
Section snippets
Experiment
Pyrrole (py) monomer was distilled under reduced pressure, put in a desiccator, and stored in the refrigerator to use.
PPy was prepared by chemical oxidation in nitrogen atmosphere. Methoxy ethanol was added to a specific amount of Fe(NO3)3·9H2O contained in a 100-ml round bottom flask containing a magnetic stir bar, and then few drops of distilled pyrrole were added to the stirred solution (the mole ratio of Fe(NO3)3·9H2O:pyrrole monomer = 1:1, 2:1, 3:1, 4:1, and 5:1, respectively). After a
The characterizations of materials
The FTIR transmission spectra of PPy and PPy/r-Fe2O3 using KBr pellets were recorded (Fig. 1). In the spectra of PPy, the specific absorption bands are observed at 1560 cm−1, 1398 cm−1, 1298 cm−1, 1211 cm−1, 1047 cm−1, 930 cm−1, and 790 cm−1. They are close to those reported data [25], [26]: stretching vibration (1560 cm−1) of CC bond, stretching vibration (1298 cm−1) of CC bond, stretching vibration (1211 cm−1) of CN bond, and bond (1398 cm−1) of pyrrole ring. In the PPy/r-Fe2O3 spectra, peaks of PPy are
Conclusion
In order to develop the new gas sensors, we put emphasis on organic–inorganic materials, and firstly studied the gas sensitivity of PPy/r-Fe2O3 to NH3 and H2S. The materials were characterized by FTIR, XRD, TG-DTA, SEM, and HRTEM. The r-Fe2O3 particle in PPy/r-Fe2O3 was spherical as it can be seen from SEM and HRTEM. The results of gas sensitivity test suggested that PPy had the maximum sensitivity to NH3 and H2S at the mole ratio Fe(NO3)3·9H2O:py = 3:1 at room temperature, but the sensitivity
References (29)
- et al.
Sens. Actuators B
(2004) - et al.
Sens. Actuators B
(2004) - et al.
Solid State Electron.
(2004) - et al.
Sens. Autuators B
(2003) Songliao J. (Nat. Sci. Ed.)
(2002)- et al.
Sens. Autuators B
(1995) - et al.
Radiat. Phys. Chem.
(2003) - et al.
Sens. Actuators B
(1995) - et al.
Sens. Actuators B
(2003) - et al.
Sens. Actuators B
(1995)
Mater. Sci. Eng. C
Sens. Actuators B
J. Colloid Interface Sci.
Sens. Actuators B
Cited by (59)
Recent progress in hybrid conducting polymers and metal oxide nanocomposite for room-temperature gas sensor applications: A review
2023, Sensors and Actuators A: PhysicalUnravelling the roles of Ginkgo biloba L. for modification of nanoscale zero valent iron in persulfate system to remove antibiotic resistance genes by the tool of metabonomic analysis
2021, Chemical Engineering JournalCitation Excerpt :As seen in Fig. 3d, the peaks at 2θ = 44.8°, 65.0° and 82.5° were assigned to Fe0 [26]. In addition, the presence of γ-Fe2O3 was also observed even though the peaks were weak at 35.1° and 65.5° [27]. The peaks of γ-Fe2O3 in the nZVI were hard to discern, which might be due to low degree of crystallinity, or the overlapping with the peak of Fe0.
A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution
2016, Journal of Magnetism and Magnetic MaterialsCitation Excerpt :Recently conducting polymers with nano-sized composites are drawing much interest because of their low density, diversified structure with unique physical and chemical properties [1–3].
Parallel spinnerets electrospinning fabrication of novel flexible luminescent-electrical-magnetic trifunctional bistrand-aligned nanobundles
2014, Chemical Engineering JournalCitation Excerpt :Up to now, investigation on the luminescent–electrical–magnetic twi- or trifunctional materials has become one of the popular subjects in the field of materials science [11–14]. Electromagnetically functionalized micro/nanostructures of conducting polymers are of special interest due to their potential applications in areas such as electromagnetic interference shielding [15], microwave absorption [16], nonlinear optics [17] and biomedicine [18]. Previously, polyaniline nanotubes containing Fe3O4 NPs have been fabricated by an in situ chemical oxidation polymerization in the presence of Fe3O4 NPs [19].
Novel Trends in MXene/Conducting Polymeric Hybrid Nanoclusters
2023, Journal of Cluster Science