Speaker
Mr
Olatunbosun Nubi Nubi
(University of Limpopo)
Description
Nanometric powders of titanium dioxide (TiO2) were prepared by the sol-gel synthesis of titanium isopropoxide. With Ag and Cu as dopants, single and double doped samples, at doping levels of 5% molar weight, were achieved. In addition, undoped samples were also prepared. The samples were dried in air at 100°C and post annealing was done at 300°C and 900°C, in order to obtain the anatase and rutile polymorphs respectively. The changes in the electrical conductivities of representative anatase and rutile TiO2 nanopowders upon exposure to water-vapour, ammonia (NH3) and hydrogen (H2) were then investigated. Sensing measurements for water-vapour was done at room temperature for various humidity levels ranging from 5.4% RH to 88.4% RH. The detection of NH3 and H2 gases were carried out at temperatures extending from room temperature to 350°C and over concentration ranges of 25 sccm to 500 sccm and 15 sccm to 200 sccm respectively. The gas-sensing results show that the sol-gel fabricated TiO2 nanoparticles (particularly in anatase form), has excellent fast and stable dynamic responses to humidity, NH3 and H2. They feature good sensitivities, even at a low operating temperatures. However, acceptor behaviour, for which there was a conductivity switch from n-type to p-type, was recorded for the Ag-doped rutile powders at operating temperatures of 300°C and 350°C. Overall, the double-doped sample annealed at 300°C was deemed the most promising candidate for gas-sensing.
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
N/A
Apply to be<br> considered for a student <br> award (Yes / No)?
No
Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?
Yes
Primary author
Mr
Olatunbosun Nubi Nubi
(University of Limpopo)
Co-author
Dr
Thuto Mosuang
(University of Limpopo)
