1. Department of Nano Science and Technology and Department of Materials Science and Engineering, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan, and Catalyst Division, Parts & Components Sector, Mitsui Mining & Smelting Co., Ltd., 1013-1 Ageoshino̅, Ageo, Saitama 362-0025, Japan