Dandelion-like SiO2@SnO2/α-Fe2O3 hollow spheres formed by growing of α-Fe2O3 nanotubes on low crystalline SiO2@SnO2 and their enhanced acetone-sensing properties

Abstract

Herein, dandelion-like SiO2@SnO2/α-Fe2O3 hollow microspheres with average size of 600 nm were successfully synthesized by an in-site hydrothermal method. The α-Fe2O3 nanotubes with average diameters of 30 nm were epitaxially grown on the low crystalline mesoporous SiO2@SnO2 hollow spheres. The hollow microspheres owned mesoporous structure, while the pore size and the specific surface area were 8.8 nm and 86.7 m2/g, respectively. The influence of the Fe3+ initial concentration on structure, morphology and gas-sensing property of the as-synthesized products were studied. Compared with α-Fe2O3, SiO2@SnO2, and other SiO2@SnO2/α-Fe2O3 composites, the sensor based on SiO2@SnO2/α-Fe2O3-0.15 (the concentration of Fe3+ was 0.15 μM) showed excellent gas sensitivity, which had high response value (41 towards 100 ppm acetone), faster response and recovery time (7 s and 23 s) and a lower detection limit. The remarkable improvement of gas-sensing performance could be attributed to the unique mesoporous SiO2@SnO2/α-Fe2O3 hollow structure with α-Fe2O3 nanotubes, the large specific surface area, the catalysis of α-Fe2O3 and the synergistic effect of SiO2, SnO2 and α-Fe2O3. The sensor based on dandelion-like SiO2@SnO2/α-Fe2O3 hollow microspheres would be a potential application in acetone gas detection.