The comparison of gas sensing properties between hierarchical porous and nonporous SnO2 microflowers

The hierarchical porous and nonporous SnO2 microflowers was successfully synthesized by a simple hydrothermal method and followed by calcination procedure. The microstructure and morphology of the product were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy (SEM). The SEM images display that the prepared SnO2 is a microflower composed of countless thin sheets, and each of the sheets covered in a series of porous by calcining at 500 A degrees C. Nevertheless, there is no porous when it treated at 400 A degrees C. The results of comparison show that the hierarchical porous SnO2 microflowers (HPSM) sensors possess a preferable gas-sensing property. The response of HPSM sensors to 100 ppm ethanol is 205.6 at the optimum operating temperature 240 A degrees C. Which sensitivity is almost 3.9 higher than the hierarchical nonporous SnO2 microflowers (HNSM) (52.9). Meanwhile, the response and recovery times of HPSM (HNSM) are 3 s (3 s) and 45 s (145 s) to 100 ppm ethanol, respectively. What's more, the minimum concentration of ethanol that we can detect is 0.1 (1.0) ppm, and the response value is 1.9 (2.0). At last, both HPSM and HNSM own a good selectivity.