1. Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P. R. China
2. School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
3. BGI College & Henan Institute of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450052, P. R. China
4. CUSTech Institute of Technology, Wenzhou, Zhejiang 325024, P. R. China
5. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, United States