Photochemical Decoration of Metal and Metal-Oxide Nanoparticles on Highly Oriented SnO₂Nanorod Films for Improved Hybrid Gas Sensors and Photo-Detectors

Highly oriented SnO 2 nanorods were grown on Si/SiO 2 substrates by using the Vapor-Liquid-Solid (VLS) technique; the resulting nanorods were decorated with Au, Ag, and NiO nanoparticles on separated samples using the UV photochemical decoration approach. The pre-decoration precursor solutions were prepared at same molarity ratio and were used for a chemical bath under UV light exposure during the same irradiation time and same solution volume. The as-decorated nanorod films were characterized afterwards using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). Chemical sensitivity studies reveal a significant improvement on time responses and selectivity to Ethanol (C 2 H 5 OH) and acetone (C 3 H 6 O) vapors for SnO 2 -Au and SnO 2 -NiO hybrid devices. Photoconductivity experiments show a significant increase on photocurrent densities related with Au and Ag decoration as well as a decrease on photocurrent density related with NiO decoration. The study reported here suggests the selective tuning on gas sensing and photosensitivity properties of SnO 2 hybrid devices and the methods used are described and compared in detail.