Synthesis of Ag@AgBr/CaTiO₃ composite photocatalyst with enhanced visible light photocatalytic activity

A novel efficient visible light driven Ag@AgBr/CaTiO₃ composite photocatalyst was successfully fabricated by deposition–precipitation method, followed by photo-reduction route. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectra and photoluminescence emission spectra were employed to characterize the crystal structure, morphology, chemical composition and optical properties. The photocatalytic activity of the samples was evaluated by the degradation of methyl orange (MO) aqueous solution under visible light irradiation. The results showed that the loading amount of Ag@AgBr had a significant effect on the photocatalytic activity. Among the photocatalysts studied, the as-prepared Ag@AgBr/CaTiO₃-3 photocatalyst presented the highest photocatalytic activity under visible light irradiation, degrading more than 98% of MO within 12 min. The enhanced photocatalytic performance could be attributed to the surface plasmon resonance effect induced by Ag nanoparticles, and the formed heterostructure at the interface of Ag@AgBr and CaTiO₃, resulting in high separation efficiency of photogenerated electron and hole pairs. In addition, the trapping experiment results demonstrated that h⁺ and \(^{ \cdot }{{\text{O}}_2}^{ - }\) played the key roles for MO degradation. The possible degradation mechanism of MO over Ag@AgBr/CaTiO₃ composite under visible light was tentatively proposed.