Ag nanoparticle dispersed TiO2 thin films by single step sol gel process: Evaluation of the physical properties and photocatalytic degradation

Abstract

The photocatalyst must be low cost, high performing, and recyclable for efficient water treatment applications. Herein, we deposited TiO2 and Ag-dispersed TiO2 thin films via sol-gel spin coating and post-deposit annealing at 400 °C for 50 min. The physical properties of TiO2 and Ag: TiO2 thin films were analyzed by X-ray, Raman analysis, Atomic Force Microscope, Scanning Electron Microscopy, Electron Dispersive Spectroscopy, Transmission Electron Microscopy, and UV–visible transmittance spectroscopy. The structural evaluation established that the films were of anatase phase without any peaks related to metallic Ag or Ag oxides. The scanning transmission electron microscopy images demonstrated the presence of Ag nanoparticles with a diameter of ∼8 nm distributed on the film surface. The cross-sectional images from the high-angle annular dark-field scanning transmission electron microscopy confirmed the presence of Ag nanoparticles along the thickness of the Ag: TiO2 thin films. The optical bandgap of the Ag: TiO2 samples red shifted from 3.35 eV to 3.00 eV when the doping concentration reached 8 wt%. Photocatalysis showed by all samples were analyzed following the degradation of methylene blue (MB) with UV-light illumination. The Ag: TiO2 thin films demonstrated a substantial improvement in photocatalytic efficiency. The 4 wt% Ag doped TiO2 sample degraded 98% of MB in 180 min, a degradation efficiency 60% higher than the undoped samples.