1. Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province
2. College of Chemistry and Chemical Engineering
3. Lanzhou University
4. Lanzhou 730000
5. P. R. China
6. Laboratoire de Physique et Chimie de Nano-Objets
7. Université de Toulouse
8. 31077 Toulouse
9. France
10. School of Chemistry and Chemical Engineering
11. East China University of Science and Technology
12. Shanghai 200237