1. State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 P. R. China
2. University of Science and Technology of China Hefei 230026 P. R. China
3. Physical Science and Engineering Division (PSE) King Abdullah University of Science and Technology (KAUST) Thuwal 23955‐6900 Saudi Arabia
4. School of Petrochemical Technology Lanzhou University of Technology Lanzhou 730050 P. R. China