1. Center for Nanochemistry Beijing Science and Engineering Center for Nanocarbons Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
2. Beijing Graphene Institute (BGI) Beijing 100095 P. R. China
3. Key Laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective Technologies Ningbo Institute of Materials Technology and Engineering (NIMTE) Chinese Academy of Sciences Ningbo 315201 P. R. China
4. College of Chemistry and Chemical Engineering Ningxia University Yinchuan 750021 P. R. China
5. School of Materials Science and Engineering Ulsan National Institute of Science and Technology Ulsan 44919 Korea
6. School of Materials Science and Engineering Peking University Beijing 100871 P. R. China