1. Center for Advanced Research of Energy Conversion Materials, Hokkaido University, N13 W8, Kita-ku, Sapporo 080 8628, Japan
2. Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816 8580, Japan
3. Curtin Center for Advanced Energy Science and Engineering, Curtin University of Technology, 1 Turner Avenue, Technology Park, WA 6102, GPO Box U1987, Perth, Western Australia 6845, Australia