1. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
2. Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
3. School of Physics and Electronics, Central South University, Changsha 410083, P. R. China
4. School of Chemical, Biological and Environment Engineering, Oregon State University, Corvallis, Oregon 97331, United States
5. X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
6. Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
7. Department of Earth and Environmental, Sciences and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States