1. Laboratory of Industrial Chemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, 44780 Bochum, Germany
2. College of Environmental Science and Engineering, North China Electric Power University, 102206 Beijing, P. R. China
3. Beijing Key Laboratory of Function Materials for Molecule & Structure Construction, School of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing, P. R. China