1. State Key Laboratory of New Ceramics and Fine Processing
2. School of Materials Science and Engineering
3. Tsinghua University
4. Beijing 100084
5. China
6. Key Laboratory of Advanced Materials (MOE)
7. Department of Physics and Center for 2-Dimensional and Layered Materials
8. The Pennsylvania State University
9. USA
10. Shenyang National Laboratory for Materials Science
11. Institute of Metal Research
12. Chinese Academy of Sciences
13. Shenyang 110016
14. Institute of Carbon Science and Technology
15. Shinshu University