Photocatalytic Degradation of Congo Red and Methyl Orange Dye Under Visible Light Using Silver and Iron co-doped TiO2 Nanoparticles

Abstract

In the present report TiO₂ nanoparticles co-doped with iron and different mol % of silver have been successfully synthesized by sol-gel route and studied by X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), UV-visible absorption spectroscopy (UV-Vis), Photoluminescence spectroscopy (PL), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), and FTIR spectroscopy. The XRD data analysis confirms the formation of mixed phases of TiO₂ (anatase) and Ag₂O phase. The crystalline size was vary from 48.0 nm to 44.6 nm determined from XRD further verified from TEM micrograph. The EDXS measurements suggest that iron is completely incorporated however silver has not incorporated into TiO₂ matrix. The optical band gap of the prepared nanoparticles was calculated by UV-Visible absorption spectroscopy using Tauc-Davis and Mott expression and found to varying from 2.92 to 2.30 eV. The absorption bands in the UV-visible spectra shift towards higher wave length region and appearance of emission bands in PL spectra confirms the formation of energy substates in the forbidden gap of the prepared samples. TEM micrographs showed that prepared nanoparticles are somewhat spherical in shape. The formation of different functional groups and bonds in the structure of synthesized nanoparticles as observed in FTIR spectra helps in degradation of organic dyes (congo red and methyl orange) and enhance the photocatalytic activity under visible light. It is observed that the higher doping concentration of silver causes to decrease the band gap energy as a result the carrier recombination rate decreases and therefore enhance the degradation efficiency.