Solar light induced photocatalytic degradation of Reactive Blue 220 (RB-220) dye with highly efficient Ag@TiO_2 core-shell nanoparticles: A comparison with UV photocatalysis

摘要

Ag core-TiO_2 shell (Ag@TiO_2) structured nanoparticles with Ag to TiO_2 molar ratio of 1:1.7 were synthesized using one pot synthesis method and post calcination was carried out at 450 ℃ for 3 h to convert it from amorphous to crystalline form. The Ag core and TiO_2 shell formation was confirmed by TEM and AFM. The particle size analysis revealed the average size of Ag@TiO_2 as approximately around 30 nm. 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_2 exhibited better photocatalytic activity as compared to Degussa P25-TiO_2, synthesized TiO_2, and the Ag doped TiO_2 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_2 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_2 can be recycled without much decline in the efficacy. Ag@TiO_2 has been found to be the effective photocatalyst for degradation of water contaminated with azo dyes under both UV and solar light irradiations.