Influence of Precursor Chemistry on Morphology and Composition of CVD-Grown SnO₂ Nanowires

Tin oxide (SnO 2 ) nanowires (NWs) were synthesized via the gold-catalyzed chemical vapor deposition of tin(IV) and tin(II) precursors, namely, [Sn(O t Bu) 4 ] ( 1 ) and [Sn(O t Bu) 2 ] 2 ( 2 ). Nanowires were deposited on gold-coated Si(001) substrates, following the vapor–liquid–solid mechanism. Energy-dispersive X-ray (EDX) analysis and high-resolution transmission electron microscopy (HR-TEM) measurements on individual nanostructures showed that the change in tin valence from +IV to +II has significant influence on the morphology and composition of the resulting NWs. Whereas 1 led directly to the growth of SnO 2 nanowires, 2 underwent a disproportionation reaction whereby the elemental phase (Sn 0 ) reacted with Au nanoparticles to form a Au–Sn intermetallic catalyst. Comparative analysis of gas-sensing behaviors of nanowires grown from 1 and 2 illustrated that crystallographic imperfections, such as oxygen deficiency and a change in the oxidation states of the cations, are subject to the precursor configurations (Sn:O ratio in 1 and 2 ) and can significantly alter the surface properties, such as transduction behavior and electronic transport, that are responsible for their sensitivity toward analyte gases.