A Solution-Phase, Precursor Route to Polycrystalline SnO2 Nanowires That Can Be Used for Gas Sensing under Ambient Conditions

Abstract

This paper describes a solution-based, precursor method for the facile synthesis of uniform nanowires containing rutile SnO₂ nanocrystallites. In a typical procedure, nanowires of ∼50 nm in diameters and up to 30 μm in length were obtained as a white precipitate by refluxing SnC₂O₄·2H₂O and poly(vinylpyrrolidone) in ethylene glycol. Structural analyses by XRD, FT-IR, and TGA indicate that these highly anisotropic nanostructures were formed in an isotropic medium through the aggregation of chainlike precursors that were, in turn, formed via polyol-mediated oligomerization. These nanowires could be further converted to polycrystalline SnO₂ by calcination in air at 500 °C. The resultant nanowires of SnO₂ were highly porous and could be used for gas sensing with improved sensitivity and reversibility under ambient conditions. We have also demonstrated that this new approach could be extended to generate polycrystalline nanowires of other metal oxides such as In₂O₃ and anatase TiO₂.