Effects of ambient humidity and temperature on the NO2 sensing characteristics of WS2/graphene aerogel

The effects of ambient humidity and temperature on the NO2 sensing characteristics of WS2/graphene aerogel (WS2/GA) composite are investigated. In order to probe the gas sensing performances of WS2/GA, the sensor is fabricated by integrating WS2/GA with a microfabricated two-electrode device. The WS2/GA is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen porosimetry. This hybrid nanomaterial is found to improve the selectivity to NO2, compared to control graphene and WS2 aerogels. The NO2 sensing performance of the WS2/GA-based sensors is investigated under different relative humidities(0-60%), and ambient temperatures (room temperature (RT) to 180 degrees C). In all cases, the sensors exhibit p-type behavior. In dry atmosphere, faster response and better recovery are obtained with increasing temperature, reaching optimum sensing performance around 180 degrees C. At room temperature, interestingly, humidity is found helpful for enhancing the response and recovery of the sensor to NO2. Detection limits in the range of 10-15 ppb NO2 were determined. A possible gas sensing mechanism for this composite aerogel is proposed. (C) 2018 Elsevier B.V. All rights reserved.