Well-aligned Nd-doped SnO2 nanorod layered arrays: preparation, characterization and enhanced alcohol-gas sensing performance

Abstract

Well-oriented neodymium doped SnO₂ layered nanorod arrays were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide at 210 °C. The morphology and phase structure of the Nd-doped SnO₂ nanoarrays were investigated by X-ray powder diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman scattering spectroscopy, X-ray photoelectron spectroscopy and the BET method. The results demonstrated that the Nd-doped SnO₂ layered nanorod arrays showed a unique nanostructure combined together with double layered arrays of nanorods with a diameter of 12 nm and a length of several hundred nanometers. The Nd-doped layered SnO₂ nanoarrays kept the crystal structure of the bulk SnO₂ and possessed more surface defects caused by the Nd ions doped into the SnO₂ lattice. The Nd dopant acts as a crystallite growth inhibitor to prevent the growth of SnO₂ nanorods. An investigation into the gas-sensing properties indicated that the optimized doping level of 3.0 at% Nd-doped SnO₂ layered nanorod arrays exhibited an excellent sensing response toward alcohol at a lower temperature of 260 °C. The enhanced sensor performance was attributed to the higher specific surface area, multi-defect surface structure and the excellent catalytic properties of Nd dopant that is able to increase the amount of active sites on the surface of semiconducting oxides. The Nd-doped SnO₂ nanoarray sensors were considered to be a promising candidate for trace alcohol detections in environmental gas monitoring.