1. School
of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
2. Department
of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585 Singapore
3. Beijing
Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
4. National Center for Nanoscience and Technology (NCNST), Beijing 100190, China