To cite this article: Inderan, V. et al. (2019). A comparative study of structural and ethanol gas sensing properties of pure, nickel and palladium doped SnO2 nanorods synthesised by the hydrothermal method. J. Phys. Sci., 30(1), 127–143, https://doi.org/10.21315/jps2019.30.1.10
SnO2 nanostructures are usually modified with some metal dopants in order to improve its gas sensing properties. In this work, pure tin oxide (SnO2), nickel (Ni) doped SnO2 (Ni:SnO2) and palladium (Pd) doped SnO2 (Pd:SnO2) nanorods were successfully synthesised via hydrothermal method at low temperature (180°C) without templates or further calcination. All the samples were systematically analysed using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The sensor response (R = R0/Rg) towards 1000 ppm ethanol gas was investigated using nitrogen gas as a carrier gas. XRD results confirmed that all samples consisted of rutile tetragonal-shaped SnO2. It was found that the average diameter of nanorods formed in Ni:SnO2 and Pd:SnO2 were decreased to ~6 nm and ~10 nm, compared with nanorods formed in pure SnO2 (~25 nm). The gas sensing results indicated that the sensor properties of SnO2 were enhanced after the doping process. At 450°C, the Pd:SnO2 nanorod sensor recorded the highest response value towards 1000 ppm ethanol gas which is 15 times higher than pure SnO2 nanorods. Interestingly, all samples showed similar response time, ~ 40 s. However, pure SnO2 and Ni:SnO2 nanorods sensors exhibited longer recovery time compared to Pd:SnO2 nanorods. Pd:SnO2 nanorods recorded only 12 min of almost 100% recovery. It is proposed that Pd:SnO2 sensor could be a promising candidate for the detection of ethanol gas.