1. Department of Applied Chemistry The University of Tokyo 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656 Japan
2. Research Center for Solar Energy Chemistry Osaka University 1-3 Machikaneyama Toyonaka, Osaka 560-8531 Japan
3. Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Toyonaka, Osaka 560-8531 Japan
4. Japan Science and Technology Agency (JST) PRESTO 4-1-8 Honcho Kawaguchi, Saitama 332-0012 Japan
5. National Institute for Materials Science 1-2-1 Sengen Tsukuba, Ibaraki 305-0047 Japan