Selective metal ions doped CeO2 nanoparticles for excellent photocatalytic activity under sun light and supercapacitor application

Herein, photocatalytic activity of pure CeO2 and different metal ions (Ag, Bi, Cd and Pb) doped CeO2 nanoparticles (NPs) is investigated using degradation of methylene blue (MB) dye under direct sunlight irradiation. In addition, electrochemical supercapacitor was performed for selected metal ion doped CeO2 NPs. All the NPs are synthesized by one-step chemical precipitation method in aqueous medium at room temperature. The prepared samples were characterized by XRD, FE-SEM, TEM, FT-IR, Laser Raman, UV-Vis, PL, EPR, TGA and electrochemical techniques. According to XRD analysis, the synthesized pure CeO2 and doped CeO2 NPs are cubic crystal structure. Among the dopants, Ag doped CeO2 exhibited excellent photocatalytic activity by degrading of more than 99.5% of the MB dye within 120 min irradiation under sunlight. The enhanced photocatalytic activity of doped CeO2 NPs was ascribed to the significant suppression of the recombination rate of photo-generated electron-hole pairs due to charge transfer, increasing oxygen vacancy and the smaller optical band-gap. The reason behind the photocatalytic activity enhancement is studied through photoluminescence (PL) and the results indicated that the emission peak intensity of pure CeO2 decreased compared to the doped CeO2. The PL quenching was associated with a decrease in the electron-hole recombination rate. Electrochemical supercapacitor was performed for the best photocatalyst of Ag doped CeO2 NPs, the result found to be specific capacitance of 456 F g(-1) at 3 A g(-1) current density. Among the different metal ions, the Ag doped CeO2 showed as an excellent catalyst for dye degradation and electrochemical supercapacitor applications.