Highly crystalline {010} facet grown α-MoO3 nanobelts for resistive sensing of n-butanol vapor at room temperature

The present work is aimed at developing an n-butanol sensor based on the chemi-resistive principle using MoO3 nanostructures as a sensing element. Highly ordered free-standing alpha-MoO3 nanobelts were synthesized using hydrothermal technique. The synthesis parameters adapted in the present work have paved a way in obtaining distinct MoO3 nanostructure with minimal process time as compared with the earlier reports. Initially, the formation of monoclinic crystals with an end centered lattice of beta-Mo9O26 was observed, which then is transformed into orthorhombic alpha-MoO3 on calcination at 450 degrees C for 5 h. XPS profiles of the nanobelts revealed the presence of molybdenum and oxygen in a stoichiometric ratio of 2.6. Penta- and hexa-coordinated defect centers of Mo5+ and oxygen vacancies were observed from the photoluminescence spectra. The nanobelts respond to n-butanol vapors at room temperature with a 75-fold signal increase and response-recovery times of 17 & 10 s, respectively. The lowest detection limit is 1 ppm. The influence of relative humidity on the sensing response was also studied.