Solar light induced photocatalytic degradation of Reactive Blue 220 (RB-220) dye with highly efficient Ag@TiO2 core-shell nanoparticles: A comparison with UV photocatalysis

Abstract

Ag core-TiO<inf>2</inf> shell (Ag@TiO<inf>2</inf>) structured nanoparticles with Ag to TiO<inf>2</inf> molar ratio of 1:1.7 were synthesized using one pot synthesis method and post calcination was carried out at 450°C for 3h to convert it from amorphous to crystalline form. The Ag core and TiO<inf>2</inf> shell formation was confirmed by TEM and AFM. The particle size analysis revealed the average size of Ag@TiO<inf>2</inf> as approximately around 30nm. EDS spectra showed the presence of O, Ag, and Ti elements. The improvement in optical properties was proved by DRS which showed significant red shift by Ag core in visible region. Ag@TiO<inf>2</inf> exhibited better photocatalytic activity as compared to Degussa P25-TiO<inf>2</inf>, synthesized TiO<inf>2</inf>, and the Ag doped TiO<inf>2</inf> photocatalysts under UV and solar light irradiation for degradation of Reactive Blue 220 (RB-220) dye. Higher rate of photocatalysis of RB-220 with Ag@TiO<inf>2</inf> was obtained under solar light irradiation as compared to UV light irradiation, confirming the capability of the catalyst to absorb both UV and visible light. The kinetics of degradation of dye was found to follow modified Langmuir Hinshelwood (L-H) kinetic model. Ag@TiO<inf>2</inf> can be recycled without much decline in the efficacy. Ag@TiO<inf>2</inf> has been found to be the effective photocatalyst for degradation of water contaminated with azo dyes under both UV and solar light irradiations. © 2013 Elsevier Ltd.