1. State Key Laboratory of Environment-Friendly Energy Materials, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, P. R. China
2. Institute of Environmental Energy Materials and Intelligent Devices, School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology. Chongqing 401331, P. R. China
3. Ecomaterials and Renewable Energy Research Center, School of Physics, Nanjing University, Nanjing 211102, P. R. China