1. School of Science, Chongqing University of Technology, Chongqing 400054, P. R. China
2. Institute of Applied Physics and Materials Engineering, University of Macau, Macao SAR, 999078, P. R. China
3. Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Macao SAR, 999078, P. R. China
4. Chongqing Key Laboratory of New Energy Storage Materials and Devices, Chongqing 400054, P. R. China