Bulk and surface modification of TiO2 with sulfur and silver: Synergetic effects of dual surface modification in the enhancement of photocatalytic activity

摘要

Sulfur ion (S6+) was incorporated into the TiO lattice (TiSO) using sulfur powder as precursor. 0.05 of silver was deposited on the surface of TiSO by photoinduced deposition method. The photocatalytic reactivity of TiO, Ag-TiO, TiSO and Ag-TiSO photocatalysts were probed for the degradation of a model compound congo red (CR) dye under UV/solar light illumination. FTIR and XPS results suggested that the dopant sulfur ion (S6+) was incorporated into the TiO crystal lattice at Ti4+ lattice site and the sulfur ions on the surface were modified as SO2- active sites serving as electron withdrawing group. TEM and XPS analysis of Ag-TiSO has confirmed the deposition of silver in the Ag0 state. Ag-TiSO shows better photoactivty under solar light irradiation 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 SO2- 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. © 2015 Elsevier Ltd.