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 In/sub 2/O/sub 3/ and SnO/sub 2/ nanoparticles is presented. These materials were carefully characterized by HRTEM and XPD. They exhibit grain sizes on the nanoscale (around 2.5 nm for SnO/sub 2/ and 20 nm for In/sub 2/O/sub 3/) and are well crystallized even at such small size. Using the same approach, also In/sub 2/O/sub 3/-SnO/sub 2/ 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 (NO/sub 2/) and reducing gases (CO and CH/sub 4/). The sensors were found to show linearity in a wide range of concentration, rapid response and recovery times.