1. State Key Lab of Superhard Materials, College of Physics, Jilin University, Changchun 130012, P.R. China
2. Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
3. School of Physical Science and Technology, Ningbo University, Ningbo 315211, P.R. China
4. Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea