Sea urchins-like WO3 as a material for resistive acetone gas sensors

Abstract

Tungsten oxide (WO3) with different morphologies (nanorods, spheres, sea urchins and flowers) were synthesized by a hydrothermal method. Among them, the WO3 based gas sensor with sea urchin morphology (WO3-3) exhibits excellent sensitivity, selective and ultrafast response to acetone in the concentration range of 2–5000 ppm at 200 ℃. The response of WO3-3 sensor to 100 ppm acetone can reach 29.7 and the response time is ultrafast (3 s), which makes the sensors a promising candidate for practical applications. As temperature is one of the important factors that affect the sensor performance, we also investigated the effects of temperature on the as-prepared WO3 structures using Raman spectroscopy. Changes in the spectra measured for the different WO3 structures were seen over a temperature range from 60 to 200 ℃. Raman spectra were also measured for the WO3-3-based sensor exposed to air and acetone at room temperature and the optimum working temperature. The temperature studies using Raman spectroscopy expanded our understanding of the interactions between the gas and gas sensing materials in the WO3-based sensors. The excellent sensing properties of the WO3-3-based sensors is attributed to the special, urchin-shaped structure as well as the oxygen activity and oxygen vacancy regulation in these materials.