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

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.