A Comparative Study of Structural and Ethanol Gas Sensing Properties of Pure, Nickel and Palladium Doped SnO2 Nanorods Synthesised by the Hydrothermal Method

Abstract

A comparative study of structural and ethanol gas sensing properties of pure, nickel and palladium doped SnO 2 nanorods synthesised by the hydrothermal method. J. Phys. Sci. , 30(1), 127–143, ABSTRACT: SnO 2 nanostructures are usually modified with some metal dopants in order to improve its gas sensing properties. In this work, pure tin oxide (SnO 2 ), nickel (Ni) doped SnO 2 (Ni:SnO 2 ) and palladium (Pd) doped SnO 2 (Pd:SnO 2 ) 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 = R 0 /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 SnO 2 . It was found that the average diameter of nanorods formed in Ni:SnO 2 and Pd:SnO 2 were decreased to ~6 nm and ~10 nm, compared with nanorods formed in pure SnO 2 (~25 nm). The gas sensing results indicated that the sensor properties of SnO 2 were enhanced after the doping process. At 450°C, the Pd:SnO 2 nanorod sensor recorded the highest response value towards 1000 ppm ethanol gas which is 15 times higher than pure SnO 2 nanorods. Interestingly, all samples showed similar response time, ~ 40 s. However, pure SnO 2 and Ni:SnO 2 nanorods sensors exhibited longer recovery time compared to Pd:SnO 2 nanorods. Pd:SnO 2 nanorods recorded only 12 min of almost 100% recovery. It is proposed that Pd:SnO 2 sensor could be a promising candidate for the detection of ethanol gas.