1. Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
2. National Center for Nanoscience and Technology, Beiyitiao No. 11, Zhongguancun, Beijing 100190, P. R. China
3. State
Key Laboratory of Tribology, Tsinghua University, Beijing 100084, P. R. China
4. Center of
Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej
34, Zabrze 41-819, Poland
5. Institute
for Complex Materials, IFW Dresden, P.O. Box 270116, Dresden 01171, Germany
6. College
of Physics, Optoelectronics, and Energy and Collaborative Innovation
Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, P. R. China