1. Shenzhen Geim Graphene Center Tsinghua‐Berkeley Shenzhen Institute & Tsinghua Shenzhen International Graduate School Tsinghua University Shenzhen 518055 P. R. China
2. Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201210 P. R. China
3. Shenyang National Laboratory for Materials Sciences Institute of Metal Research Chinese Academy of Sciences Shenyang Liaoning 110016 P. R. China