Nanostructured molybdenum oxide thin film as a chemiresistor for ozone sensing

This work demonstrates the promising performance of a nanostructured molybdenum oxide film deposited by rf-magnetron sputtering, as an ozone gas sensor. X-ray diffraction and scanning electron microscopy analyses revealed that the film comprises of α-MoO3/γ-Mo4O11 nanostructures, exhibiting rice-like shape particles with an average length of 78 nm and a diameter of 25 nm. Gas-sensing measurements revealed that the nanostructures detected ozone levels ranging from 25 up to 225 ppb, operating optimally at 250 oC, with a stable response, good repeatability, and total reversibility. At a 50 % relative humidity, the sensor response varied only ∼1 % at low and ∼12 % at high ozone concentrations compared to dry conditions, indicating low humidity interference. Moreover, the films exhibited selectivity toward ozone over NO₂, NH₃, CO₂, and CO, even at low concentrations. These findings demonstrate the great potential of α-MoO3/γ-Mo4O11 film for practical environmental monitoring applications.