H2S sensing properties of nanocrystalline Sr2FeO.6NiO.4MoO6 thick film prepared by sol-gel citrate method

Nanocrystalline Sr₂FeMoO₆ (SFMO) belonging to the group of double perovskite oxides, was prepared by the sol-gel citrate method. The structural and microstructural characterization has been carried out with the help of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. XRD of Sr₂Fe_1−xNi_xMoO₆ (SFNMO) shows the formation of solid solution with average grain size of about 40 nm. A comparative study of gas sensing behaviour of Sr₂FeMoO₆ and Sr₂Fe_1−xNi_xMoO₆ with reducing gases like hydrogen sulfide (H₂S), liquid petroleum gas (LPG), hydrogen (H₂), ethanol (C₂H₅OH) and carbon monoxide (CO) were also discussed. The sensitivity is calculated by measuring the change the resistance of the sensor material in the presence of gas. Among the different composition of x (x = 0.2, 0.3, 0.4, 0.5), Sr₂Fe_0.6Ni_0.4MoO₆ (x = 0.4) shows better response to H₂S gas at 260 °C. Incorporation of palladium (Pd) improves the gas response, selectivity, response time and reduced the operating temperature from 260 to 220 °C for H₂S gas.