1. State Key Laboratory of Urban Water Resource and Environment School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150001 China
2. Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 China
3. Condensed Matter Science and Technology Institute Harbin Institute of Technology Harbin 150001 China
4. Department of Physics King's College London The Strand London WC2R 2LS UK
5. Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy Aarhus University Aarhus 8000 Denmark