Hydrothermal synthesis porous silicon/tungsten oxide nanorods composites and their gas-sensing properties to NO2 at room temperature

In this paper, well-ordered one-dimensional single crystalline hexagonal WO3 nanorods were synthesized directly on the porous silicon substrates by a seed-induced hydrothermal method without using any template, catalyst. And the effect of the annealing temperature of WO3 seed layers on the microstructure and NO2-sensing properties was studied. The morphology and crystal structure of the porous silicon/WO3 nanorods composites were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The gas-sensing properties of the porous silicon/WO3 nanorods composite gas sensors to NO2 with the concentration ranging from 100 ppb to 3 ppm were examined. The results indicate that well-ordered WO3 nanorods can greatly improve the gas-sensing properties of the sensor. The sensor exhibited a high response (∼3.38) and excellent selectivity toward 1 ppm NO2 at room temperature. And the NO2-sensing mechanism of this sensor was further explained.