摘要
在避光条件下采用溶胶凝胶法制备了Ag TiO2 光催化剂 ,通过XRD ,Raman ,PL和XPS表征及对光催化降解罗丹明B的性能评价 ,发现Ag的掺入抑制了TiO2 锐钛矿相的晶化 ,促进了TiO2 由锐钛矿相向金红石相的转变 .随着掺Ag量的增加 ,PL光谱强度下降 ,这说明Ag掺入抑制了光生电子空穴的复合 .在较低掺杂浓度区 (Ag/Tiatom <3 % )以Ag+ 的迁移、扩散为主 ,在较高浓度掺杂区 (Ag/Tiatom≥ 3 % )Ag+ 的迁移、扩散和表面还原共存 ,在浅表层扩散阈值附近 (Ag/Tiatom =3 %～ 5 % ) ,Ag TiO2 光催化剂既有丰富的浅表层电子捕获阱 ,又有利于电子向表面还原态Ag的导出 ,使光生电子和空穴的复合得到有效的抑制 ,从而使光催化效率显著提高 .当掺杂浓度大于阈值时 ,Ag TiO2
Ag-TiO2 catalysts with different contents of Ag were prepared by the sol-gel method in the absence of light. Through XRD, Raman, PL and XPS characterizations and activity evaluations of photocatalytic degradation of rhodamine B, it was found that the doped Ag promoted the phase transformation, but has a depression effect on the anatase grain growth. The PL intensity decreased with increasing of contents of Ag doping, suggesting that doped Ag inhibited recombination of photoinduced electrons and holes. In rather low doping concentration range (Ag/Ti atom < 3 %) there are mainly migration and diffusion of Ag+ ions, and in rather high doping concentration range (Ag/Ti atom greater than or equal to 3 %) migration and diffusion of Ag+ ions coexist with surface reductions. In the neighborhood of the shallow surface close to the diffusion threshold value (Ag/Ti atom = 3 % similar to 5 %), Ag-TiO2 catalysts have abundant shallow superficial layer electron traps and are favorable for the derivation towards Ag of superficial reduced state, leading to effective inhibition of recombination of photoinduced electrons and holes which significantly elevates the photocatalytic efficiency. When the silver dopant exceeded threshold value, the catalytic activity of Ag-TiO2 decreased.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2004年第12期1110-1114,MJ02,共6页
Acta Chimica Sinica
基金
国家自然科学基金 (Nos.2 0 1 71 0 1 6
2 0 30 1 0 0 6)
教育部重点项目计划 (No.0 2 0 51 )
黑龙江省杰出青年科学基金 (2 0 0 2 )
黑龙江省科学技术计划 (No.WB0 2 1 0 3)
黑龙江省自然科学基金 (No .B0 30 5)
黑龙江大学杰出科学基金 (No.JC2 0 0 30 8)资
