Ammonia gas sensing properties at low temperature of graphene oxide/tungsten oxide nanobricks nanocomposities

Abstract

Nanocomposites of graphene oxide (GO) and tungsten oxide (WO3) nanobricks were synthesized by co-dispersing graphene oxide and tungsten oxide nanobricks in bi-distilled water with different weight ratios (0.1, 0.3 and 0.5 wt.% of graphene oxide). The ammonia gas sensing properties of nanocomposites were studied at low temperatures (50, 100 and 150oC) with the static gas-testing system. The co-appearance and the strong interaction between graphene oxideand tungsten oxide in the nanocomposite were confirmed by Raman scattering analysis. The content of GO in nanocomposite strongly affects the resistance of nanocomposite-based sensors. When the working temperature increase from 50oC to 150oC, the response of sensors switches from the p-type (at 50oC) to n-type (at 150oC) behavior. At 150oC, the nanocomposite-based sensors show the most stable ammonia gas sensing characteristics. The working resistance of the pristine WO3 sensor reduced from 1.35 MΩ to 90, 72 and 27 kΩ when compositing with 0.1, 0.3 and 0.5 wt.% GOat 150oC, respectively.The 0.5 wt.% GO/WO3-based sensor shows low response but low working resistance, shorter response and recovery times (20 s and 280 s, respectively) which is promising for low power-consumption gas sensors.