1. Key Laboratory for Renewable Energy, Chinese Academy of Sciences, Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
2. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
3. College of Material Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
4. Laboratory for Advanced Materials and Electron Microscopy, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
5. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
6. Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
7. Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China