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O2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.
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+.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2004年第4期355-359,共5页
Acta Physico-Chimica Sinica
基金
中国博士后科学基金(2002032174)资助项目~~
