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ABSTRACT
Non-stoichiometric spinel ferrites are attracting increasing interest for gas sensing because their electrical and surface properties can be altered through composition control. In this work, ZnxFe₂O₄ NPs with varying zinc content (0.90, 0.95, 1.00, 1.05) were synthesised through the microwave-assisted coprecipitation method and investigated for the detection of toxic and flammable gases. The influence of non-stoichiometry on the structural, morphological, and electronic properties was examined using X-ray diffraction and transmission electron microscopy, confirming the formation of nanostructured spinel phases with controlled deviations from stoichiometry. Gas sensing measurements were performed against representative reducing gases at operating temperatures of 25 – 225°C. The results show that both zinc-deficient (x=0.90 and 0.95) and zinc-rich (x = 1.05) compositions display different sensing behaviours compared to stoichiometric ZnFe₂O₄ (x =1). The Zn0.95Fe₂O₄ exhibited the highest response of S = 2941.59 to LPG at 25°C, with a response (106s) and recovery (630s) times. These findings indicate that modifying the Zn:Fe ratio change surface adsorption sites, thereby enhancing selectivity. Overall, the study demonstrates that controlled variation of zinc in non-stoichiometry ZnxFe₂O₄ proves to be an effective strategy for improving sensitivity and selectivity of the sensor towards H2S, SO2, CO2, H2 and LPG gas detection, making them good for environmental monitoring and industrial safety applications.
| Apply for student award at which level: | MSc |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |