1. CAS Center for Excellence in NanoscienceBeijing Key Laboratory of Micro‐Nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciences Beijing 100083 P. R. China
2. Key Laboratory for Micro‐Nano Physics and Technology of Hunan ProvinceState Key Laboratory of Chemo/Biosensing and Chemometricsand College of Materials Science and EngineeringHunan University Changsha Hunan 410082 P. R. China
3. School of Nanoscience and TechnologyUniversity of Chinese Academy of Sciences Beijing 100049 P. R. China
4. Key Laboratory for Micro‐Nano Physics and Technology of Hunan ProvinceCollege of Materials Science and EngineeringHunan University Changsha Hunan 410082 P. R. China
5. Center on Nanoenergy ResearchSchool of Physical Science and TechnologyGuangxi University Nanning Guangxi 530004 P. R. China
6. College of Optoelectronic EngineeringShenzhen University Shenzhen 518060 P. R. China