1. College of Chemistry and Chemical Engineering, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Material, Northwest Normal University, Lanzhou 730070, P. R. China
2. Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
3. Chongqing Key Laboratory of Green Energy Materials Technology and Systems, Department of Physics and Energy, Chongqing University of Technology, Chongqing 40054, P. R. China