摘要
用溶胶 凝胶法制备了在可见光照射下具有光催化活性的掺杂Pt(Ⅳ )离子的非晶态微孔TiO2 ,表面积为 160～ 2 0 0m2 /g ;含 3 .0 %Pt(Ⅳ )的AMM Ti具有最大的光催化活性 .X射线精细结构分析 (EXAFS)表明 ,单个的PtCl4 分子均匀地分布在非晶态二氧化钛表面 ;用这种光催化剂降解 2 ,4 二氯苯氧基乙酸时 ,2 ,4 二氯苯酚是主要的中间物 ,通过Langmuir Hinshelwood方程的线性形式估算了反应速率常数k和吸附平衡常数K ,研究了光催化起始反应速率和反应物起始浓度之间的关系 ,同时 ,提出了Pt(Ⅳ ) /AMM Ti上电荷分离的可能机理和 2 ,4
Amorphous microporous metal oxides of titanium (AM M -Ti) which can induce photocatalytic reactions under visible light irradiation was prepared by using Na 2PtCl 6 according to the sol-gel procedure affording high specific surface areas of 160～200 m 2/g. The most active photocatalysts c ontained 3.0%Pt(Ⅳ). According to extended X-ray absorption fine structure (E XAFS) results, isolated PtCl 4 molecules were homogeneously distributed in an a lmost exclusively amorphous matrix of titania. During the photocatalytic degrada tion of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution containing a suspension of AMM-Ti, it was found that 2,4-dichlorophenol was the major int ermediate. The initial rate of photo-degradation was studied as a function of t he initial concentration of reactants by the linearised form of the Langmuir-Hi nshelwood equation, by which rate constants k and equilibrium adsorption con stants K were evaluated. The postulated charge separation mechanism at Pt( Ⅳ)/AMM-Ti and photocatalytic degradation mechanism of 2,4-D were also propos ed.
基金
ProjectsupportedbytheNationalNaturalScienceFoundationofChina(602740 61)
关键词
非晶态材料
光催化
TIO2
掺杂
Amorphous material, Photocatalytic, Titania, Modi fication
