1. Advanced Manufacturing Research Center for Hydrogen Energy, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 266101 Qingdao, P. R. China
2. Shandong Energy Institute, Qingdao 266101, P. R. China
3. Qingdao New Energy Shandong Laboratory, Qingdao 266101, P. R. China
4. Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
5. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China