1. Department of Physics, Innovation Center of Materials for Energy and Environment Technologies, College of Science, Tibet University, Lhasa 850000, China
2. Institute of Oxygen Supply, Center of Tibetan Studies (Everest Research Institute), Tibet University, Lhasa 850000, China
3. Key Laboratory of Cosmic Rays, Ministry of Education, Tibet University, Lhasa 850000, China
4. Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 7098 Liuxian Boulevard, Nanshan District, Shenzhen 518055, P. R. China