Crystalline WO3 nanoparticles for NO2 sensing

This study shows excellent NO2-sensing properties of tungsten oxide nanoparticles, prepared using a facile procedure which includes dissolution of metallic tungsten in hydrogen peroxide with subsequent low-temperature (400 degrees C) heating. We also conducted a thorough literature survey on sensor properties of tungsten oxide prepared by various means and found that the sensor response towards NO2 registered in this work achieved the highest level. The most intriguing feature of the material obtained was a highly reproducible sensor signal at room temperature which was more than 100 times higher than any reported previously for WO3. The probable reason for such high sensor response was the presence of two WO3 polymorphs (gamma-WO3 and h-WO3) in the material synthesized using a peroxide-assisted route. In order to further investigate synthesized WO3 materials, sophisticated experimental (XRD, SEM, TEM, BET) and theoretical (B3LYP, HSE) methods have been used, as well as resistance and sensor response measurements at various temperatures.