The synthesis and selective gas sensing characteristics of SnO2/α-Fe2O3 hierarchical nanostructures

SnO2/alpha-Fe2O3 hierarchical nanostructures, in which the SnO2 nanorods grow on the side surface of alpha-Fe2O3 nanorods as multiple rows, were synthesized via a three-step process. The diameters and lengths of the SnO2 nanorods are 6-15 nm and about 120 nm. The growth direction of SnO2 nanorods is [001], significantly affected by that of alpha-Fe2O3 nanorods. The hetero-nanostructures exhibit very good selectivity to ethanol. The sensing characteristics are related to the special heterojunction structures, confirmed by high-resolution transmission electron microscopy observation. Therefore, a heterojunction barrier controlled gas sensing mechanism is realized. Our results demonstrate that the hetero-nanostructures are promising materials for fabricating sensors and other complex devices.