1. CAS Center for Excellence in Nanoscience, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, P.R. China
2. Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Chinese Education Ministry, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P.R. China
3. School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, P.R. China
4. Center on Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning 530004, P.R. China
5. School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P.R. China