Vacuum-Deposited Poly(o-phenylenediamine)/WO3·nH2O Nanocomposite Thin Film for NO2 Gas Sensor

Abstract

The vacuum-deposited thin film of hydrated tungsten oxide (WO 3 . nH 2 O) embedded poly(o-phenylenediamine) (PoPD/ WO 3 . nH 2 O) nanocomposite was fabricated on an indium tin oxide (ITO) coated glass surface for potential NO 2 gas sensor application. The resulting PoPD/WO 3 . nH 2 O/ITO thin film was characterized using ultraviolet-visible spectroscopy (UVvis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and electron microscopy (SEM). The composite thin film exhibited a crystalline surface morphology containing nanocrystalls of WO 3 . nH 2 O with a diameter ranging from 5 to 10 nm. The PoPD/WO 3 . nH 2 O/ITO film allowed for the low potential detection of NO 2 gas at concentration range from 0 to 1800 ppm. The NO 2 gas sensing characteristics were studied by measuring change in the current with respect to concentration and time. The current of the PoPD/WO 3 . nH 2 O/ITO film was linearly increased with an increase in concentration of NO 2 gas with a response of $9 s.KEY WORDS: Poly(o-phenylenediamine) / Hydrated Tungsten Oxide / Vacuum-Deposition / Thin Film / Nanocomposite / NO 2 Gas Sensor / NO 2 gas is a common air pollutant and its detection from the combustion environment is an obvious requirement. The gas sensors based on metal oxides are widely used for the detection of gases.1-3 Among them, tungsten oxide (WO 3 ) is one of the most attractive technological materials for gas sensors because of its distinctive electrochromic and catalytic properties. [4][5][6][7] Recently, different types of potentiometric and amperometric gas sensors have been developed using WO 3 in the various forms such as sintered block, thick film and thin film as sensing probes.6-9 However, these sensors could provide precise data only in a limited concentration range. Also, they are expensive, large in size, and cannot operate at room temperature. With the advent of nanotechnology, nanostructured materials with novel characteristics provide new opportunities to address these challenges.Gas sensors based on nanostructured materials have attracted much attention because of their increased sensitivity due to the high surface-to-volume ratios.10 Recent development of polymer-metal nanocomposites, with every imaginable combination of physical and chemical characteristics, has led to the fabrication of efficient gas sensors that can be used for a wide range of sensor applications. 11,12 Polymer nanocomposites are easy to prepare and possess high sensing efficiency with a long shelf-life. Therefore in this work, we explore a novel material based on poly(o-phenylenediamine) (PoPD/WO 3 . nH 2 O) nanocomposite for NO 2 gas sensor application.Poly(o-phenylenediamine), PoPD is a polyaniline derivative which can be realized via substitution of an amino group in an aniline nucleus. The oxidative polymer of o-phenylenediamine has apparently shown different characteristics of molecular structure and properties in comparison with polyaniline. It is widely used as electrochemical reduction catalyst, anticorrosion co...

Investigation of structural and dielectric behavior of Eu2(B′0.5 B″0.5)2O7 (B′=Ba; B″=W, Mo) ceramics

“…The cubic pyrochlore have a general formula A 2 B 2 X 6 Y. The B 2 X 6 sub-array forms a rigid skeleton of corner-shared octahedra [13][14][15][16][17][18]. Octahedra are arranged in a tetrahedral array according to a diamond-type net and a system of open channels is observed parallel to the (1 1 0) direction and to that equivalent to cubic symmetry.…”

Nanocomposite Films for Gas Sensing

“…For example, Tiwari et al (Tiwari, 2009(Tiwari, , & 2010 used vacuum thermal evaporation of poly(ophenylenediamine) (PoPD)/WO 3 .nH 2 O mixed powder pellet to fabricate nanocomposite films of PoPD-WO 3 .nH 2 O on an indium tin oxide (ITO) coated glass surface for NO 2 gas sensor applications. Using the same method; they also prepared aniline-formaldehyde condensate (AFC)-WO 3 .nH 2 O nanocomposite films.…”

“…Other polymer nanocomposite films that were investigated for gas sensor applications include TiO 2 -porphyrin film coated on a quartz crystal to detect volatile organic compounds such as ethanol, acetone, 2-propanol, cyclohexane, toluene and o-xylene (Arshad, 2008); poly(vinyl butyral)-carbon black films prepared for methanol, propanol and hexanol vapour (Arshak, 2006); sodium polystyrenesulfonate (NaPSS)-ZnO for humidity sensors (Yang, 2002); polypyrrole (PPy)-SnO 2 , PEDT-SnO 2 , PHTh-SnO 2 and copolymer (HTh-EDT)-SnO 2 films for NO 2 gas sensing applications (Ram, 2005); poly(3-hexylthiophene)-ZnO films for NO 2 , NH 3 , CO and ethanol detection (Baratto, 2006); PoPD-WO 3 .nH 2 O (Tiwari, 2009) and AFC-WO 3 .nH 2 O (Tiwari, 2010) films for NO 2 gas sensing.…”

Nanomaterial-based VOC sensing applications and a deep dive into their developmental trends

“…Fast, non-cumbersome, and reproducible gas detection is needed. [4][5][6] Sensors for detecting VOCs are an approach to cater to the above needs. 7 VOCs are organic compounds that we encounter as gases.…”