1. School of Energy and Environment, Anhui University of Technology, Ma’anshan 243002, P. R. China
2. Low-Carbon New Materials Research Center, Low-Carbon Research Institute, Anhui University of Technology, Ma’anshan 243002, P. R. China
3. School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002, P. R. China
4. Department of Applied Physics, Faculty of Science, Tianjin University, Tianjin 300072, P. R. China
5. Department of Physics, Ludong University, Yantai 264025, P.R. China