Synthesis, characterization and activity evaluation of (Cu2O or Ag2O)-N-TiO2 photocatalysts for E. coli inhibition and trichloroethylene degradation

Abstract Heterogeneous photocatalysis has been increasingly scrutinized in order to remove air pollutants. TiO₂ is the most widely employed semiconductor, although it absorbs radiation only within the UVA range, limiting visible light radiation use. Therefore, some strategies, such as doping and sensitization, have been adopted. This project aimed to develop TiO₂-based photocatalysts using visible-UVA radiation as a future alternative for air decontamination. The synthesized photocatalysts were N-TiO₂, Cu₂O/N-TiO₂ and Ag-N-TiO₂, impregnated on a glass surface via the sol-gel dip-coating method. The materials were characterized through UV-Vis Diffuse Reflectance, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy, X-ray Diffraction and X-ray Photoelectron Spectroscopy. These techniques corroborate the formation of polytriazines as products of urea thermolysis and suggest a synergistic effect between sensitization and doping with N. All photocatalysts exhibited a new band gap with energy associated with visible light. The photocatalytic activity of the materials was verified against trichloroethylene in the gaseous phase and against the bacteria Escherichia coli. The photocatalytic efficiency of the materials was higher using UVA and visible light than pure TiO₂, both for TCE and disinfection tests. The disinfection process was accelerated in the presence of photocatalysts containing copper and under visible light, and Ag-N-TiO₂ was more efficient than when under UVA light.