1. Center on Nanoenergy Research, College of Physical Science and Technology, Guangxi University, Nanning 530004, Guangxi, PR China
2. CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro−Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, PR China
3. College of Physics Science & Information Engineering and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Shijiazhuang, Hebei 050024, China