Nonaqueous synthesis of high-purity indium and tin oxide nanocrystals and their application as gas sensors

In this work, a nonaqueous and halide-free synthesis of In₂O₃ and SnO₂ nanoparticles is presented. These materials were carefully characterized by HRTEM and XPD. They exhibit grain sizes on the nanoscale (around 2.5 nm for SnO₂ and 20 nm for In₂O₃) and are well crystallized even at such small size. Using the same approach, also In₂O₃-SnO₂ mixed oxide phases were successfully synthesized. Gas sensors were fabricated using the synthesized nanopowders. The good sensitivity of these sensors was demonstrated by monitoring trace levels of both oxidizing (NO₂) and reducing gases (CO and CH₄). The sensors were found to show linearity in a wide range of concentration, rapid response and recovery times.