1. Energy Catalyst Technology Group, Energy Process Research Institute (EPRI), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
2. Artificial Photosynthesis Research Team, Global Zero Emission Research Center (GZR), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan