Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (04): 355-359.doi: 10.3866/PKU.WHXB20040404

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Mechanism of Silver Modification for the Enhanced Photocatalytic Activity of Cr(VI) Reduction on TiO2 Photocatalyst

Liu Shou-Xin;Sun Cheng-Lin   

  1. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023;Northeast Forestry University, Harbin 150040
  • Received:2003-09-25 Revised:2003-11-24 Published:2004-04-15
  • Contact: Sun Cheng-Lin E-mail:clsun@dicp.ac.cn

Abstract: Under the condition that negative effects of proton starvation and photo-generated electron-hole recombination to the Cr6+ photocatalytic reduction process were minimized for the photocatalytic activities of TiO2 and Ag/TiO2 for Cr6+ reduction were comparatively investigated. Combined with the results of EPR, the mechanism of silver modification for the enhanced photocatalytic reduction of Cr6+ on TiO2 was discussed. The result revealed that Cr6+ reduction by the UV-Ag/TiO2 process was more effective than the UV-TiO2 process under the same conditions. Electron transfer from surface Ti3+ to Cr6+ was the key step for Cr6+ reduction. Cr6+ photocatalytic reduction by directly capturing photo-generated electrons is possible, but it occurs mainly indirectly by getting electrons from surface Ti3+. The higher reduction activity of Ag/TiO2 photocatalyst came mainly from the higher number of surface Ti3+.

Key words: Silver, Titanium dioxide, Photocatalytic reduction, Hexavalent chromium