1. Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
2. Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
3. State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong 999077, China
4. Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
5. Department of Physics, Ewha Womans University, Seoul 03760, Korea
6. School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
7. Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China
8. Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China