1. Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources
2. School of Materials and Chemical Engineering
3. Hainan University
4. Haikou 570228
5. PR China
6. Department of Physics and Institute of Theoretical Physics and Astrophysics
7. Xiamen University
8. Xiamen 361005
9. Department of Mechanical Engineering
10. National University of Singapore
11. Singapore 117576
12. Singapore