Pt nanoparticles functionalized tungsten oxynitride hybrid chemiresistor: Low-temperature NO2 sensing

Abstract

Semiconducting metal oxides (SMOs) based gas sensors are inherently hampered by requirement of high working temperature because of their wide bandgaps. Consequently, there are remain challenges to utilize SMOs based gas sensors with regard to continuous gas monitoring platform with low power consumption. To address the inherent limitation, nitridation (i.e., N doping) of WO3 NFs to WOxNy NFs was herein introduced for realization of low-temperature NO2 sensing. Importantly, nitridation was conducted at intervals of 50 degrees C from 400 to 600 degrees C to adjust the degree of phase transition from semiconducting WO3 to conducive WON phases. To further optimize the conductivity and improve the sensing characteristics, i.e., reduction of optimal operating temperature and enhancement of sensitivity, WOxNy NFs were functionalized with platinum (Pt) catalytic nanoparticles (NPs) by physical mixing. Pt-NPs functionalized WOxNy NFs nitrided at 550 degrees C exhibited improved normalized resistance change and superior selectivity against C2H2OH, C7H8, CH4, CO, NH3, and NO at 50 C. The noble metal catalyst-metal oxynitride hybrid system is suggested as an effective NO2 sensing platform for low-temperature chemical sensor.