1. Center of Excellence in Nanotechnology (CENT); King Fahd University of Petroleum and Minerals; KFUPM Box 5040 Dhahran 31261 Saudi Arabia
2. Center of Research Excellence in Renewable Energy, Research Institute, King Fahd; University of Petroleum and Minerals; Dhahran 31261 Saudi Arabia
3. Chemistry Department; King Fahd University of Petroleum and Minerals; KFUPM Box 5040 Dhahran 31261 Saudi Arabia
4. Department of Material Chemistry, Graduate School of Engineering; Kyoto University; Nishikyo-ku, Kyoto 615-8520 Japan