Kinetic and DIFT studies on the Ag/TiO2-photocatalyzed selective reduction of nitrobenzene to aniline
Kinetic and DIFT studies on the Ag/TiO2-photocatalyzed selective reduction of nitrobenzene to aniline
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DOI：
10.1002/cphc.200500031
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发表时间：
2005-08-12
期刊：
影响因子：
2.9
通讯作者：
Kobayashi, H
中科院分区：
文献类型：
--
作者：
Tada, H;Ishida, T;Kobayashi, H
负载平均直径为1.5 nm的银纳米粒子的TiO2在CH3OH（浓度= 100 m m）存在下具有很高的光催化活性（照射1 h后转化率为84%），可100%选择性地将硝基苯还原为苯胺。对pt光沉积Ag/TiO2的高分辨率透射电镜研究表明，Ag非粒子在光催化反应中充当了还原位点。光谱测量和密度泛函理论（DFT）计算表明，硝基苯通过部分电子从Ag转移到硝基苯，选择性地吸附在Ag/TiO2的Ag表面，而苯胺与Ag/TiO2之间的相互作用较弱。动力学分析表明，流入Ag纳米粒子的电子与TiO2价键中留下的空穴之间的复合被明显抑制，特别是在CH3OH存在的情况下。从电荷分离效率、催化剂表面对反应物的选择性吸附以及对产物再吸附的限制等方面证明了Ag/ tio2光催化还原的高活性和选择性。
TiO2 particles loaded with silver nanoparticles with a mean diameter of 1.5 nm exhibit a high photocatalytic activity (84% conversion after I h irradiation) for the reduction of nitrobenzene to aniline with 100% selectivity in the presence of CH3OH (concentration = 100 m m). High-resolution transmission electron microscopic studies of Pt-photodeposited Ag/TiO2 demonstrate that the Ag nonoparticles act as reduction sites in the photocatalytic reaction. Both spectroscopic measurements and density functional theory (DFT) calculations reveal that nitrobenzene is selectively adsorbed onto the Ag surfaces of Ag/TiO2 via partial electron transfer from Ag to nitrobenzene, whereas the interaction between aniline and Ag/TiO2 is weak. The kinetic analysis indicates that the recombination between the electrons flowing into the Ag nanoparticle and the holes left in the TiO2 valence bond is significantly suppressed, particularly in the presence of CH3OH. The high activity and selectivity in the present Ag/TiO2-photocatalyzed reduction ore rationalized in terms of the charge separation efficiency, the selective adsorption of the reactants on the catalyst surfaces, and the restriction of the product readsorption.