金纳米簇光敏化二氧化钛紫色光照射下选择性催化氧化苄胺

Gold Nanocluster Photosensitized TiO_(2) Photocatalysis:Selective Oxidation of Benzylamine under Violet Light

用加热还原法合成谷胱甘肽(GSH)保护的金纳米簇(Au-GSH),并用浸渍法将其负载到二氧化钛(TiO_(2))上,得到Au-GSH-TiO_(2)复合材料,用高分辨透射电镜(HR-TEM)、X射线衍射(XRD)、紫外-可见漫反射(UV-Vis DRS)等技术对样品进行了表征。以苄胺的选择性氧化为模型反应,空气中的氧气为氧化剂,LED灯为光源,构建了异相可见光催化反应体系,并在优化的反应条件下,探究了其反应机理。实验表明,当Au-GSH负载量为3.36%、紫色光(400 nm)照射、ST-01型TiO_(2)为载体、乙腈为溶剂时光催化效率最高,1 h转化率达78%。上述反应符合零级动力学特征,反应速率常数为0.024 mol·L^(-1)·h^(-1)。在该反应体系中,TiO2提供了反应平台,金纳米簇吸收可见光将电子注入TiO2发生光生电子空穴分离,O_(2)^(·-)为反应体系的活性氧物种。

Glutathione-protected gold nanoclusters(Au-GSH)were synthesized by heat reduction method,and were modified on the surface of TiO_(2) by impregnation method.The prepared Au-GSH-TiO_(2) samples were characterized by high resolution transmission electron microscopy(HR-TEM),X-ray diffraction(XRD),and UV-visible diffuse-reflectance spectrum(UV-Vis DRS).A heterogeneous photocatalytic reaction was constructed using the selective oxidation of benzylamine as the model reaction,the oxygen in the air as the oxidant,and the LED as the light source.The reaction mechanism was investigated under the optimized reaction condition.The results showed that when the loading capacity of Au-GSH was 3.36%,violet light(400 nm)was the light source,TiO_(2)(ST-01)was the carrier and CH3CN was the solvent,the catalytic efficiency was the highest,and the conversion rate could reach 78% after 1 h reaction.The kinetic studies indicated that for the visible light driven selective oxidation benzylamine exhibited the characteristics of zero order reaction kinetics with a reaction rate constant of 0.024 mol·L^(-1)·h^(-1).In the reaction,the Au-GSH nanocluster was excited to generate electrons and holes under light,and the photogenerated electrons were injected into the TiO2 for generating O_(2)^(·-) as the reactive oxygen species.