1. Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
2. Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
3. School of Chemistry, University of Birmingham, Edgbaston, Birmingham, West Midlands B15 2TT, United Kingdom
4. Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
5. Centre for Materials Science, School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland 4001, Australia
6. Australian Synchrotron Clayton, 800 Blackburn Rd, Clayton, Victoria 3168, Australia
7. Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
8. Department of Molecules & Materials, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands