1. CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 P. R. China
2. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Science Beijing 100049 P. R. China
3. School of Physical Science and Technology ShanghaiTech University Shanghai 201210 P. R. China
4. State Key Lab of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 P. R. China
5. Center for Clean Energy Technology School of Mathematical and Physical Science Faculty of Science University of Technology Sydney Ultimo NSW 2007 Australia