Green fabrication of Ag/AgCl@TiO 2 superior plasmonic nanocomposite: Biosynthesis, characterization and photocatalytic activity under sunlight

The synthesis of photocatalysts revealing efficient performance under the visible light has recently broadened its appeal for the removal of environmental pollutants from the water and wastewater. Besides, the biosynthesis of nanostructured photocatalysts with the tunable surface plasmon band is eco-friendly and worth attending. In the same vein, this study was an endeavor to synthesize Ag/AgCl@TiO2 plasmonic photocatalyst, with an enhanced photoactivity under the sunlight by a facile biosynthesis method using aqueous leaf extract of mangrove plant Avicennia marina, as a reducing and stabilizing agent as well as a chlorine source. To this end, the plasmonic Ag/AgCl@TiO2 nanocomposite, with the particle size of ∼35 nm, the specific surface area of 31.94 m2 g−1, and the bandgap energy of 1.73 eV, was successfully synthesized with aqueous leaf extract/AgNO3 (R1) and AgNO3/TiO2 (R2) ratios of 0.31 and 1.61, respectively. Different techniques examined the effect of R1 and R2 on the characteristics of the products. Consequently, the results indicated that Ag/AgCl@TiO2 nanocomposite exhibited a swift degradation of the eosin Y dye in 60 min under the sunlight. A topmost dye photodegradation of 99% was attained at pH 4 with the photocatalyst concentration of 0.05 g/100 mL and the eosin Y concentration of 50 mg/L at the ambient temperature. The surface plasmon resonance and the effective charge separation due to the heterostructure developed among Ag, AgCl, and TiO2 could be accountable for the absorption band expansion to the visible light area and the significant photocatalytic activity of Ag/AgCl@TiO2 under the sunlight. Recycling experiments for the five cycles elucidated the magnificent long-term photocatalytic stability of the biosynthesized Ag/AgCl@TiO2. The operation simplicity and the potential of utilizing the sunlight energy prompted the biosynthesized Ag/AgCl@TiO2 to be a noteworthy reusable candidate for the photodegradation of the toxic organic pollutants in the aqueous solutions. © 2020 Elsevier B.V.