Effect of pH on particles size and gas sensing properties of In₂O₃ nanoparticles

In this work, indium oxide (In₂O₃) nanoparticles have been synthesized by co-precipitation method and the effect of pH on the structural and sensor response values of In₂O₃ nanoparticles has been reported. X-ray diffraction pattern (XRD) revealed the formation of cubic phase In₂O₃ nanoparticles. FESEM results indicate the formation of nearly spherical shape In₂O₃ nanoparticles. The band gap energy value changed with change in pH value and found to have highest value at pH 9. Indium oxide nanoparticles thus prepared were deposited as thick films on alumina substrates to act as gas sensors and their sensing response to ethanol vapors and LPG at 50 ppm was investigated at different operating temperatures. It has been observed that all sensors exhibited optimum response at 300°C towards ethanol and at 400°C towards LPG. In₂O₃ nanoparticles prepared at pH 9, being smallest in size as compared to other, exhibit highest sensor response (SR).