1. Center for NanochemistryBeijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking University Beijing 100871 P. R. China
2. School of Materials Science and EngineeringNanyang Technological University Singapore 639798 Singapore
3. College of ScienceChangchun University Changchun 130022 P. R. China
4. Shanghai Synchrotron Radiation FacilityZhangjiang Laboratory Shanghai 201204 P. R. China