1. School of Chemistry and Chemical EngineeringAnhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized MaterialsInstitute of Physical Science and Information TechnologyAnhui University Hefei 230601 P. R. China
2. School of Materials Science and EngineeringGeorgia Institute of Technology Atlanta GA 30332 USA
3. Faculty of Materials Science and ChemistryChina University of Geoscience (Wuhan) Wuhan 430074 China
4. Department of Applied PhysicsSchool of ScienceTianjin University Tianjin 300072 P. R. China