A plasmonic photocatalyst of Ag@AgBr/La${}_2$Ti${}_2$O${}_7$ with enhanced photocatalytic activity under visible light irradiation

In this paper, a plasmonic photocatalyst of Ag@AgBr/La${}_2$Ti${}_2$O${}_7$ was synthesized through a chemical precipitation method followed by a photoreduction process. The crystallinity, morphology, chemical composition, and optical properties of the as-prepared samples were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectrum. The photocatalytic activity of the samples was investigated toward the degradation of rhodamine B (RhB) under visible light irradiation. Among the obtained photocatalysts, Ag@AgBr/La${}_2$Ti${}_2$O${}_7$ displayed the highest photocatalytic activity, degrading approximate 98% of RhB within 8 min of visible light illumination. The superior photocatalytic activity of Ag@AgBr/La${}_2$Ti${}_2$O${}_7$ was attributed to the formation of heterojunctions between Ag@AgBr and La${}_2$Ti${}_2$O${}_7$ as well as the surface plasmon resonance effect of Ag nanoparticles (NPs), which would be conducive to the efficient separation of photogenerated electrons and holes. The active species trapping experiments indicated that that ⋅O${}_2^{-}$ and h${}^{+}$ were the main reactive species responsible for RhB degradation. Furthermore, a possible photocatalytic mechanism for RhB decomposition over Ag@AgBr/La${}_2$Ti${}_2$O${}_7$ was proposed.