1. School of Chemistry and Materials Science, Hunan Agricultural University, Changsha 410128, P. R. China
2. Hunan Optical Agriculture Engineering Technology Research Center, Changsha 410128, P. R. China
3. State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, P. R. China
4. Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, P. R. China
5. School of Physical and Electronics, Central South University, Changsha 410083, China