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Preparation, Characterization, and Gas Sensing Performance of WO3 Nanosheets
Introduction:
In recent years, gas sensing materials have received increasing attention due to their potential for detecting harmful gases in different applications such as environmental monitoring, industrial processes, and medical diagnosis. Among various sensing materials, tungsten oxide (WO3) has been widely studied due to its excellent physicochemical properties, such as high stability, high sensitivity, and rapid response time. In this study, we report the preparation, characterization, and gas sensing performance of WO3 nanosheets.
Materials and Methods:
The WO3 nanosheets were synthesized via a simple hydrothermal method. In brief, 1 mmol of tungsten trioxide hydrate was dissolved in 20 mL of deionized water under vigorous stirring, and then 15 mL of 10 M sodium hydroxide solution was added slowly until the solution became clear. The mixture was transferred to a Teflon-lined stainless steel autoclave and heated at 180°C for 12 h. The obtained precipitate was washed with deionized water and ethanol, followed by drying at 60°C for 12 h. The morphology and structure of the WO3 nanosheets were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The gas sensing performance of the WO3 nanosheets was investigated using a home-built gas sensing system, which is equipped with a resistance meter, an oven, and a gas source with a controlled flow rate.
Results and Discussion:
SEM and TEM images of the WO3 nanosheets indicated a uniform and continuous morphology with a thickness of about 80 nm and a length of several micrometers. XRD analysis confirmed the monoclinic crystal structure of WO3. The gas sensing measurements showed that the WO3 nanosheets exhibit high sensitivity and selectivity towards NO2 gas at different concentrations ranging from 1 ppm to 10 ppm, with a response time of about 60 s and a recovery time of about 120 s. The gas sensing mechanism of WO3 nanosheets is attributed to the interaction between the adsorbed NO2 gas molecules and the oxygen vacancies on the WO3 surface, leading to changes in the resistance of the WO3 sensor.
Conclusion:
In summary, we have successfully synthesized WO3 nanosheets via a simple hydrothermal method. The as-prepared WO3 nanosheets exhibit excellent gas sensing performance towards NO2 gas with high sensitivity and selectivity. The gas sensing mechanism is related to the interaction between NO2 gas and oxygen vacancies on the WO3 surface. This study provides a simple and effective method for the preparation of WO3 nanosheets and suggests their potential for gas sensing applications.