1. School of Chemistry and Chemical Engineering, Key Laboratory of Green Catalytic Materials and Technology in Ningxia, Ningxia Normal University, Guyuan, 756000, P. R. China
2. School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan, 750021, P. R. China
3. School of Physics and Electronic and Electrical Engineering, Ningxia University, Yinchuan, 750021, P. R. China