1. Center for Nanochemistry; Beijing National Laboratory for Molecular Sciences; Key Laboratory for the Physics and Chemistry of Nanodevices; State Key Laboratory for Structural Chemistry of Unstable and Stable Species; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 P. R. China
2. Department of Materials Science and Engineering; College of Engineering; Peking University; Beijing 100871 P. R. China
3. College of Chemistry and Molecular Sciences; Hubei Key Lab of Electrochemical Power Sources; Wuhan University; Wuhan 430072 P. R. China
4. Key Laboratory of Cluster Science; Ministry of Education School of Chemistry; Beijing Institute of Technology; Beijing 100081 P. R. China