1. School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
2. Center on Nano-Energy Research, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
3. Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
4. College of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
5. Engineering Research Center of Mechanical Testing Technology and Equipment, Ministry of Education, Chongqing University of Technology, Chongqing, 400054, China
6. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, USA