Thermal annealing induced mazy structure on MoO3 thin films and their high sensing performance to NO gas at room temperature

Abstract MoS 2 thin films were prepared by radio frequency (RF) magnetron sputtering and then annealed in air. X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM) and transmission electron microscopy (TEM) were adopted to characterize the phase structure and surface morphology. Interestingly, upon thermal annealing in air, MoS 2 thin films changed into α-MoO 3 with mazy morphology, and the thin films were covered by MoO 3 nano-sheets with a length of 30–50 nm and a width of 10 nm. α-MoO 3 thin films with mazy morphology showed excellent response to NO gas at room temperature. The response of 5% and 92% was obtained at 5 ppm and 200 ppm, respectively, and the response and recovery times were 30 s and 1500 s. Moreover, the mazy structure of MoO 3 exhibited good selectivity to NO gas with respect to SO 2 , NH 3 and H 2 gases. The high surface-to-volume ratio was the dominant factor for high sensing performance.