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

ABSTRACT

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/R_g) 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.

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