1. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
2. School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
3. Institute for Energy Research, Key Laboratory of Zhenjiang, Jiangsu University, Zhenjiang 212013, P. R. China
4. Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576, Singapore