The synthesis and selective gas sensing characteristics of SnO ₂/α-Fe₂O₃ hierarchical nanostructures

SnO₂/α-Fe₂O₃ hierarchical nanostructures, in which the SnO₂ nanorods grow on the side surface of α-Fe₂O₃ nanorods as multiple rows, were synthesized via a three-step process. The diameters and lengths of the SnO ₂ nanorods are 6-15 nm and about 120 nm. The growth direction of SnO₂ nanorods is [001], significantly affected by that of α-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.