Hydrothermally synthesized nanostructured NiTiO3 thick films for H2S and room temperature CO2 gas sensing

In this work we are presenting the hydrothermal method to synthesize NiTiO3 perovskite nanoparticles (NPs). The effect of variation in reaction temperature on the structural, optical, electrical and gas sensing properties of NiTiO3 nanoparticles was investigated. The nanoparticles synthesized at different reaction temperatures were characterized by various characterization methods like XRD, FTIR, UV-Visible Spectroscopy, FESEM, TEM, HRTEM and SAED. The results of UV-Visible analysis revealed that band gap of NiTiO3 decreased from 2.90 to 2.56 eV on increase in reaction temperature from 140 to 200 degrees C. The XRD analysis showed that crystallite size decreased in the range of 21 to 12 nm on increase in reaction temperature. The various parameters of the material like dislocation density, microstrain and crystallinity were also calculated from XRD data. The average particle size was estimated by FESEM analysis and found to be decreased on increase in reaction temperature. FTIR analysis confirmed the formation of NiTiO3. Study of electrical properties proved the semiconducting behaviour of NiTiO3. The detail analysis of NiTiO3 sensor characteristics in terms of sensitivity, selectivity, response and recovery time was carried out. The study of gas sensing performance of NiTiO3 revealed that NiTiO3 synthesized at 140 degrees C showed maximum sensitivity to CO2 gas at room temperature, whereas NiTiO3 synthesized at 200 degrees C showed maximum sensitivity to H2S gas at 250 degrees C.