Nanostructured Oxides and their Applications in Gas Sensing and Photocatalysis
Nouar Tabet, M. Faiz , N. Maalej A. Mekki, A. Sunaidi and Z. Yamani
Physics Department, Center of Research Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.
Metal oxides such as TiO2, ZnO, SnO2 and In2O3 are semiconducting materials that have been extensively studied because of their potential use in photocatalysis and gas sensing applications. Nanostructured oxides have major advantages due to their high surface-to-volume ratio and high crystallinity as compared to conventional materials. For instance, Indium oxide nanowires have shown a sensitivity that is five orders of magnitude better than that of thin-film based sensors. As a result, the detection of gas concentrations as small as 20ppb became possible. Furthermore, drastic enhancement of the sensitivity can be achieved by decorating the surface of the oxide nanowires with metallic nanoparticles. The mechanism leading to the observed enhancement is still the subject of debate.
The synthesis of nanostructures of controlled size, morphology and chemical properties is of critical importance for the development of applications. A wide range of techniques can be used to fabricate nanostructures of different shapes including nanospheres, nanosheets, nanorods and nanowires. A novel method based on the metal evaporation/oxidation using a microwave susceptor as a source of heat is described. The catalytic and gas sensing properties of oxide nanostructures prepared by this technique using both Ohmic and Schottky contacts will be discussed.
Acknowledgment
This work is supported by KACST- NSTIP Project 08-NAN92-4. |
