1. CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro–Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, P. R. China
2. College of Chemistry and Chemical Engineering, Center on Nanoenergy Research, Guangxi University, Nanning, P. R. China
3. Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, P. R. China
4. School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, P. R. China