1. Institute of Resources Utilization and Rare Earth Development, Guangdong Academy of Sciences, Guangzhou510651, P. R. China
2. School of Chemistry, Sun Yat-Sen University, Guangzhou510275, P. R. China
3. School of Marine Sciences, Sun Yat-Sen University, Zhuhai519082, P. R. China
4. College of Science, Chongqing University of Posts and Telecommunications, Chongqing400065, P. R. China