Investigation of Gas-Sensing Performance of ${\rm SnO}_{\rm 2}$ Nanoparticles With Different Morphologies

Abstract

Two forms of tin oxide (SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) nanoparticles (NPs) with different morphologies (small dispersed NPs and big clusters aggregated from small NPs) were synthesized via chemical solution methods and assembled into films on Si/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> substrate for a comparative sensing study, which were tested for the responses to H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S reducing gas and NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> oxidizing gas, respectively. Similar detection limits to part per million levels H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S reducing gas and part per billion (ppb) levels NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> oxidizing gas were observed for both films with different morphologies at room temperature. It was found, however, that the small NP film showed higher sensitivity and detection limit to H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S down to ppb levels after surface modification by depositing Au nanocatalysts, while SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> big cluster film presented better sensitivity to NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> detection down to ppb levels with/without the nanocatalyst modification, much determined by the morphology of these two forms of NPs. The sensing mechanism is also discussed.