1. Beijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciences Beijing 100083 P. R. China
2. School of Nanoscience and TechnologyUniversity of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Institute for Advanced Interdisciplinary Research (iAIR)University of Jinan Jinan 250022 P. R. China
4. Center on Nanoenergy ResearchSchool of Physical Science and TechnologyGuangxi University Nanning 530004 P. R. China
5. School of Materials Science and EngineeringGeorgia Institute of Technology Atlanta Atlanta GA 30332‐0245 USA