1. Department of ChemistryNational University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
2. Centre for Advanced 2D Materials and Graphene Research CentreNational University of Singapore Singapore 117546 Singapore
3. Department of Materials Science and EngineeringNational University of Singapore 9 Engineering Drive 1 Singapore 117575 Singapore
4. Department of PhysicsNational University of Singapore 2 Science Drive 3 Singapore 117551 Singapore
5. Singapore Synchrotron Light SourceNational University of Singapore 5 Research Link Singapore 117603 Singapore