Concurrent Synthesis and Immobilization of Ag Nanoparticles over TiO(2) via Plasma Reduction for Photocatalytic Treatment of Methyl Blue in Water

Pure TiO(2) nanoparticles (TiO(2)NPs) were produced via the sol–gel method and then coated with silver nanoparticles (AgNPs) to reduce their optical band gap. The concurrent synthesis and immobilization of AgNPs over TiO(2)NPs was achieved through the interaction of an open-air argon plasma jet with a solution of silver nitrate/stabilizer/TiO(2)NPs. The one-pot plasma synthesis and coating of AgNPs over TiO(2)NPs is a more straightforward and environmentally friendly method than others. The plasma-produced Ag/TiO(2) nanocomposites were characterized and tested for their photocatalytic potential by degrading different concentrations of methyl blue (MB) in water. The dye concentration, oxidant dose, catalyst dose, and reaction time were also optimized for MB degradation. XRD results revealed the formation of pure AgNPs, pure TiO(2)NPs, and Ag/TiO(2) nanocomposites with an average grain size of 12.36 nm, 18.09 nm, and 15.66 nm, respectively. The immobilization of AgNPs over TiO(2)NPs was also checked by producing SEM and TEM images. The band gap of AgNPs, TiO(2)NPs, and Ag/TiO(2) nanoparticles was measured about 2.58 eV, 3.36 eV, and 2.86 eV, respectively. The ultraviolet (UV) results of the nanocomposites were supportive of the degradation of synthetic dyes in the visible light spectrum. The AgNPs in the composite not only lowered the band gap but also obstructed the electron–hole recombinations. The Ag/TiO(2) composite catalyst showed 90.9% degradation efficiency with a 5 ppm dye concentration after 120 min of light exposure.