1. State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 P. R. China
2. School of Physics and Technology Wuhan University Wuhan 430072 P. R. China
3. College of Energy Xiamen University Xiamen 361102 P. R. China
4. National Synchrotron Radiation Research Center Hsinchu 30076 Taiwan
5. Max Planck Institute for Chemical Physics of Solids 01187 Dresden Germany
6. Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM) Xiamen 361005 P. R. China