Al-Doped SnO2 Flower-Like Microspheres with Hierarchical Nanorods Synthesized by Hydrothermal Method and H2 Sensing Property

Al-doped SnO2 flower-like microspheres with hierarchical nanorods have been synthesized by hydrothermal method. The influences of alkaline concentration, hydrothermal reaction time, as well as Al doping content on the morphology, crystal structure were investigated. The SnO2-based samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy analysis (EDS), transmission electron microscopy (TEM), and AC impedance analyzer. It was observed that the crystallinity and crystallite sizes of SnO2-based powders can be improved at the higher alkaline concentration (10:1). Nanostructure evolution of SnO2-based powders was found to be influenced by alkaline concentration and hydrothermal reaction time. A possible growth mechanism of SnO2 flower-like microspheres with hierarchic) cal nanorods was proposed. H-2 sensing properties of n-type SnO2-based sensors were also studied at working temperature (WT) from room temperature (RT) to 470 degrees C using N-2 as a reference. The results showed that most sensitivities of 1-2 wt% Al-doped SnO2 sensors were higher than 50% at optimal working temperature (OWT, 270 degrees C). The highest H-2 gas sensitivity was approach to be 74.2% at 270 degrees C, which was six times of undoped SnO2 sensor. Our study shed important light on a feasible approach to design and fabricate H-2 gas sensors with high performances.