Synthesis of magneto-plasmonic Au-Ag NPs-decorated TiO2 -modified Fe3O4 nanocomposite with enhanced laser/solar-driven photocatalytic activity for degradation of dye pollutant in textile wastewater

The synergistic effect of plasmonic Au-Ag nanoparticles (NPs) on the increase of absorption band of nano-sized TiO2 and magnetic property of Fe3O4 NPs on the separation-ability of this semiconductor was applied for preparation of eight magneto-plasmonic photocatalysts for degradation of rhodamine-6G (Rh6G) in textile wastewater. The size, structure, morphology, crystallinity and optical and magnetic properties of prepared photocatalysts have been evaluated by various characterization techniques. Their photocatalytic activities were assessed under irradiation of an intense linear 405-nm laser and a continuous solar-simulated xenon lamp. The results were demonstrated that in comparison to the magnetic TiO2, the mono- and bi-plasmonic alloyed photocatalysts reveal more efficient photocatalytic activity due to the presence of one/two SPR generated hot electrons from excited Au/Ag shells under solar-simulated light radiation so that the ternary Au-Ag@TiO2 @ Fe3O4 NPs revealed similar to 4 times more photocatalytic activity under xenon lamp irradiation. Effect of different parameters such as type of photocatalyst, pH and photocatalyst dose on the degradation efficiency of Rh6G was investigated and reusability studies were revealed only a slight decrease (below 8%) in the photocatalytic performance of the catalysts after carrying out five consecutive cycles of dye photodegradation which makes them promising platforms for development of photocatalytic wastewater treatment and other applications.