1. Center for Nanochemistry (CNC), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P.R. China
2. Beijing Graphene Institute (BGI), Beijing, 100095, P.R. China
3. Shannxi Key Laboratory of Ultrasonics, Shannxi Normal University, Shaanxi 710119, P.R. China
4. Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, P.R. China
5. Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China