1. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore
2. Institute of Materials Research and Engineering, A*Star (Agency for Science, Technology and Research), Singapore 117585, Singapore
3. Centre for Advanced 2D Materials, Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
4. College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, P. R. China
5. Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, P.R. China
6. Guangdong Provincial Key Laboratory of Petrochemical Pollution Process and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, P. R. China