物理化学学报 >> 2004, Vol. 20 >> Issue (04): 355-359.doi: 10.3866/PKU.WHXB20040404

研究论文 上一篇    下一篇

Ag改性提高TiO2对Cr(VI)的光催化还原活性机理

刘守新;孙承林   

  1. 中国科学院大连化学物理研究所,大连 116023;东北林业大学,哈尔滨 150040
  • 收稿日期:2003-09-25 修回日期:2003-11-24 发布日期:2004-04-15
  • 通讯作者: 孙承林 E-mail:clsun@dicp.ac.cn

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

摘要: 在消除了质子缺乏、光生电子-空穴复合对Cr6+光催化还原负效应影响下,比较了TiO2和Ag/TiO2(Ag质量分数 1.0%)光催化还原活性.结果表明,相同条件下Ag/TiO2表现出比TiO2更高的催化活性. EPR分析表明,对于Ag/TiO2,UV照射后Ag表面有活性物种生成,在TiO2上有活性中心表相Ti3+生成.光生电子通过表相Ti3+向Cr6+传递电子是Cr6+光催化还原的速度控制步骤.较多的表相Ti3+参与还原反应是Ag/TiO2表现出较高催化活性的主要原因,担载Ag上积聚光生电子的较强流动性对反应也起到一定促进作用.

关键词: 银, 二氧化钛, 光催化还原, 六价铬, 机理

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