Enhanced photocatalytic degradation of methyl orange using Ag/Sn-doped CeO₂ nanocomposite

Cerium oxide (CeO₂) has attracted much attention in recent years because of its unique physiochemical properties in photocatalysis. Herein, pure CeO₂ and Sn-doped CeO₂ (Sn–CO) nanoparticles were synthesized by a simple hydrothermal method. In addition, the Sn-doped CeO₂ sample was composited with Ag nanoparticles by a chemical precipitation method to prepare Ag/Sn–CO nanocomposite. The prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and UV-visible absorption spectroscopy. Furthermore, the photocatalytic activity of the as-prepared cerium oxide-based samples was evaluated using the degradation of methyl orange (MO) under ultraviolet and visible light irradiation. It was found that photocatalytic activity of the pure CeO₂ nanoparticles was enhanced through Sn doping and surface sensitization with Ag. The enhanced photocatalytic performance of the Sn-doped CeO₂ sample can be ascribed mainly to a decrease in its band gap energy. Moreover, the improved photocatalytic activity of the Ag/Sn–CO nanocomposite compared to that of the Sn–CO sample is due to its localized surface plasmon resonance (LSPR) effect. The Ag/Sn–CO sample exhibited an efficient photocatalytic characteristic for degrading MO under visible light irradiation with a high degradation rate of 99% after 45 min. The responsible mechanism for the enhancement of photocatalytic activity of cerium oxide was discussed.