Hydrothermal synthesis of SnO2 hierarchical nanostructures and their gas sensing properties

Gas sensing performances of SnO2 can often be improved remarkably once the thickness of nanosheets shrinks to a critical value of 14 nm (2 lambda(D)) or self-assembly of two-dimensional nanoscale building blocks into three-dimensional (3D) complex superstructures. Here, using the hydrothermal method, we synthesise the SnO2 3D hierarchical nanostructures assembled with ultrathin nanosheets with a thickness as thin as 9-12 nm by adding sodium oxalate (Na2C2O4). Wondrously, using oxalic and sodium hydroxide (H2C2O4 + 2NaOH) substitute for equimolar Na2C2O4, the dimensions of nanosheets decrease, which may be due to the active degree is different between the Na2C2O4 directly and indirectly obtained by H2C2O4. In property, the as prepared SnO2 hierarchical nanostructures display excellent gas sensing functions to ethanol gas due to their subsize and the plane to plane contacts.