1. Engineering Research Center of Nano-Geo Materials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, No. 388 Lumo Road, Wuhan 430074, China
2. School of Physics, Hubei University, Wuhan 430062, P. R. China
3. Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, U.K.