1. Research Center of Resource Chemistry and Energy Materials and State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China
2. College of Material Science and Engineering, Lanzhou University of Technology, Lanzhou 730000, PR China
3. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China