Abstract
The MoO3 nanobelts have been grown onto the glass substrates using chemical spray pyrolysis (CSP) deposition technique at optimized substrate temperature of 400°C. XRD study shows that the film is polycrystalline in nature and possesses an orthorhombic crystal structure. The FE-SEM micrographs show the formation of nanobelts-like morphology of MoO3. The presence of Pd and its oxidation states in Pd-sensitized MoO3 film is confirmed using EDAX and XPS study, respectively. The percentage gas response is defined as |Rg-Ra|Ra×100% where, Ra and Rg are the film resistances in presence of air and analyte gas, respectively. Before Pd sensitization, MoO3 nanobelts show NO2 gas response of 68% for 100ppm concentration at operating temperature of 200°C with response and recovery times of 15s and 150s, respectively. Selectivity coefficient study shows that the Pd-sensitized MoO3 nanobelts are more sensitive and selective towards NO2 gas among various gases such as NH3, H2S, CO, CO2 and SO2. The Pd-sensitized MoO3 nanobelts shows the enhanced response of 95.3% towards 100ppm NO2 gas concentration with response and recovery times of 74s and 297s, respectively. The lower detection limit is found to be 5ppm which is four times less than immediately dangerous to life or health (IDLH) value of 20ppm. Finally, the proposed NO2 gas sensing mechanism based on chemisorption model is discussed.
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