Synergistic effect of Ag deposition and nitrogen doping in TiO2 for the degradation of phenol under solar irradiation in presence of electron acceptor

Ag deposited nitrogen doped TiO2 (Ag–TiO2−xNx) was prepared using sol gel titania by grinding it with stoichiometric amount of Urea as nitrogen source followed by the photoreduction of Ag+ to Ag0. These samples were characterized by powder X-ray diffraction (PXRD), UV-visible absorption spectroscopy, Fourier transformed infrared spectroscopy (FTIR), photoluminescence (PL) and scanning electron microscope (SEM). PL analysis of the samples indicated that the electron-hole recombination has been effectively inhibited after the Ag deposition on TiO2 and TiO2−xNx. Ag–TiO2−xNx exhibits much higher visible-light photocatalytic activity when compared with N-doped or pristine TiO2. The catalysts along with the oxidants can accelerate electron transfer process and inhibit the fast electron-hole recombination. The observed high process efficiency (Φλ) of Ag–TiO2−xNx particles compared to TiO2−xNx and pure TiO2 photocatalyst can be accounted to the synergistic effect of Ag loading along with N doping. Strongly interacting electron accepting species such as hydrogen peroxide and ammonium persulphate chemisorbed at the photocatalyst surface are said to act like surface states enabling inelastic transfer of electrons from the conduction band to the oxidizing species. The electronic states of different energies within the band gap have a major role in enhancing the efficiency.

► The use of electron acceptors in photocatalytic reactions involving silver deposited nitrogen doped TiO2 is never attempted.
► The electronic states of different energies within the band gap have a major role in enhancing the efficiency.
► The mechanism of electron transfer from semiconductor to metal and vice versa is explained in detail.
► Photocatalytic activity of these catalysts is explained based on the photoluminescence results.
► Synergistic effect between nitrogen dopant and Ag deposition is shown to enhance the photocatalytic activity.