Insitu controllable synthesis of MoO3 nanoflakes and its temperature-dependent dual selectivity for detection of ethanol and isopropanol

Nanostructures significantly affect the performance of metal oxide semiconductor (MOS) based gas sensors. Herein, we proposed a method of inducing sulfur-doping (S-doping) in the synthesis to control the morphology of MoO3 nanoflakes. The MoO3 nanoflakes prepared with increased S-doping have morphologies with decreased thickness, increased aspect ratio, increased surface area and increased surface chemisorbed oxygens, which improved sensing properties including higher response, better selectivity to ethanol and lower critical temperatures for the temperature-dependent dual selectivity. The response to 500 ppm ethanol at 350°C was improved by 3-fold as compared to the MoO3 obtained without S-doping. The sensors exhibited a temperature-dependent dual selectivity to isopropanol (IPA) and ethanol. The critical temperatures exhibited a decreasing trend for the gas sensors made of MoO3 which are obtained with increasing S-doping. The feasibility of inducing S-doping in the preparation to modify the morphology of MoO3 nanoflakes and using it to enhance the gas sensing performance are reported for the first time. It should have a chance to be widely spread into the applications for which higher aspect ratio is beneficial, such as various sensors and photocatalysis.