Selectivity of Tungsten Oxide Synthesized by Sol-Gel Method Towards Some Volatile Organic Compounds and Gaseous Materials in a Broad Range of Temperatures.

Simonas Ramanavičius,Milda Petrulevičienė,Jurga Juodkazytė,Asta Grigucevičienė,Arūnas Ramanavičius

doi:10.3390/ma13030523

Simonas Ramanavičius, Milda Petrulevičienė + Show 3 more

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https://doi.org/10.3390/ma13030523

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Abstract

In this research, the investigation of sensing properties of non-stoichiometric WO3 (WO3−x) film towards some volatile organic compounds (VOC) (namely: Methanol, ethanol, isopropanol, acetone) and ammonia gas are reported. Sensors were tested at several temperatures within the interval ranging from a relatively low temperature of 60 up to 270 °C. Significant variation of selectivity, which depended on the operational temperature of sensor, was observed. Here, the reported WO3/WO3–x-based sensing material opens an avenue for the design of sensors with temperature-dependent sensitivity, which can be applied in the design of new gas- and/or VOC-sensing systems that are dedicated for the determination of particular gas- and/or VOC-based analyte concentration in the mixture of different gases and/or VOCs, using multivariate analysis of variance (MANOVA).

Highlights

Air pollution is an important environmental issue due to intensive industrial manufacturing processes, car exhaust, biomass burning, combustion of fossil fuels, and microbiological emission from soil
The crystalline structure and surface morphology of tungsten trioxide based coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM)
The WO2.9 formed in our research shows the sensitivity towards reducing gases and/or volatile organic compounds (VOC) at a slightly higher temperature (60 ◦ C), compared to that reported by some other authors for WO2.625 -based layer [4], which was sensitive towards alcohols even at room temperature (25 ◦ C)

Summary

Introduction

Air pollution is an important environmental issue due to intensive industrial manufacturing processes, car exhaust, biomass burning, combustion of fossil fuels, and microbiological emission from soil. The main air pollutants such as NOx , SH2 , NH3 , and some volatile organic compounds (VOC) contribute to a greenhouse effect and can cause respiratory diseases such as bronchitis, emphysema, as well as heart problems [1]. In the development of gasand/or VOC-sensors, metal oxides such as TiO2 , SnO2 , WO3 , and ZnO are widely used as sensing components of analytical signal transduction systems, because of their high sensitivity and stability [2,3]. The gas- and/or VOC-sensing and photoelectrochemical properties of WO3 are highly dependent on the deposition method and conditions of sensitive layer formation. Different methods, such as reactive radiofrequency (RF)

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