1. School of Metallurgy and Environment, Central South University, Changsha 410083, PR China
2. Physical Science and Electronics, Central South University, Changsha 410083, PR China
3. College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China
4. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, PR China
5. Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, 999077 Hong Kong, China
6. Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, United States