Bulk and surface modification of TiO2 with sulfur and silver: Synergetic effects of dual surface modification in the enhancement of photocatalytic activity
Sulfur ion (S6+) was incorporated into the TiO2 lattice (Ti0.85S0.15O2) using sulfur powder as precursor. 0.05% of silver was deposited on the surface of Ti0.85S0.15O2 by photoinduced deposition method. The photocatalytic reactivity of TiO2, Ag-TiO2, Ti0.85S0.15O2 and Ag-Ti0.85S0.15O2 photocatalysts were probed for the degrdn. of a model compd. congo red (CR) dye under UV/solar light illumination. FTIR and XPS results suggested that the dopant sulfur ion (S6+) was incorporated into the TiO2 crystal lattice at Ti4+ lattice site and the sulfur ions on the surface were modified as SO42- active sites serving as electron withdrawing group. TEM and XPS anal. of Ag-Ti0.85S0.15O2 has confirmed the deposition of silver in the Ag0 state. Ag-Ti0.85S0.15O2 shows better photoactivty under solar light irradn. when compared to all the other photocatalysts. The enhanced photocatalytic activity of this catalyst is attributed to the synergetic effects of the incorporated dopant electronic energy level with the dual surface modifications of the type SO42- active centers and Schottky junctions created by metallic Ag0. Further the deposited Ag particles plays a dual role one as a sensitizer due to the Surface Plasmon Resonance (SPR) effect and also acts as an electron trapper under solar light illumination reducing the recombination of photogenerated charge carriers
