Template-free synthesis of flower-like SnO2 hierarchical nanostructures with improved gas sensing performance

In the work, flower-like SnO2 hierarchical nanostructures assembled with numerous nanosheets were successfully prepared through a facile template-free hydrothermal route using SnSO4 as the tin source and water as the solvent. The process was simple, green, and effective. The obtained SnO2 products had uniform flower-like morphology, hierarchical nanostructures, and high specific surface area of 136.0 m2/g. The investigation of the experimental parameters demonstrated that the tetrapropylammonium hydroxide (TPAOH) played a crucial role in determining the structure and properties of the final products, which was acted as both the alkali source and morphology director. Ag/SnO2 nanostructures were also fabricated by a conventionally impregnation method, in which Ag nanoparticles with the size of 20-30 nm were uniformly grown into the surface of SnO2 product. The gas sensing tests indicated that both SnO2 and Ag/SnO2 sensors exhibited better gas sensing properties to n-butanol at low working temperature of 160 °C compared with the sensor based on the commercial SnO2 nanoparticles. As expected, the sensor based on the Ag/SnO2 product showed obviously enhancement in gas sensing performance. The growth process and gas-sensing mechanism were investigated based on the experimental results. The present protocol may be extended to the synthesis of other metal oxides with different nanostructures for more potential applications.