Single-step biosynthesis of Ag/AgCl@TiO2 plasmonic nanocomposite with enhanced visible light photoactivity through aqueous leaf extract of a mangrove tree

摘要： Ag/silver halides have recently received attention in the synthesis of heterostructured nanocomposites. Although important, the green biosynthesis of Ag/silver halide nanocomposites has not yet been reported. Herein, a simple, single-step biosynthesis process was implemented using aqueous leaf extract (ALE) of the mangrove Avicennia marina to synthesize Ag/AgCl@TiO2 plasmonic nanocomposites with enhanced visible light photoactivity. Characterization results showed that the ALE was necessary for nanocomposites preparation as a reducing and stabilizing agent. With increase in the ALE/AgNO3 ratio (R1) of the initial precursor from 0 to 1.63, the diffraction peaks of Ag/AgCl became visible slowly and their intensity increased. Besides, AgNO3/tetraethylorthotitanate ratio (R2) had a positive effect on increasing the intensity of Ag/AgCl diffraction peaks. The UV light absorption intensity of Ag/AgCl@TiO2 was improved and displayed stronger absorption by increasing R1 values. A broad absorption peak was recorded in the visible wavelength spectrum of the biosynthesized nanocomposites from 400 to 600 nm, centered at 500 nm, which could be associated with the surface plasmon resonance effect of spatially detained electrons in Ag/AgCl nanocrystals. This enhanced absorption showed the photoactivity of the biosynthesized nanocomposites in the visible light region, which was confirmed in a real application for degradation of eosin Y with 99.8% efficiency under sunlight. Thus, it seems that the biological procedure, which is environmentally friendly and inexpensive, could replace the conventional approaches to synthesize Ag/AgCl@TiO2 plasmonic nanocomposites with enhanced visible light photoactivity.