1. Laboratory of Applied Surface and Colloid Chemistry Ministry of Education School of Materials Science and Engineering Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology Institute for Advanced Energy Materials Shaanxi Normal University Xi'an Shaanxi 710119 P. R. China
2. School of Physics Northwest University Xi'an 710069 P. R. China
3. Institute of Nanoscience and Nanotechnology School of Materials and Energy Lanzhou University Lanzhou Gansu 730000 P. R. China
4. Dalian National Laboratory for Clean Energy iChEM Dalian Institute of Chemical Physics Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 P. R. China
5. University of Chinese Academy of Sciences Beijing 100049 P. R. China