负载金属对MoO3-TiO2光催化剂结构与催化性能的影响

用溶胶-凝胶和浸渍-还原相结合的方法制得M/MoO3-TiO2 (M=Pd, Cu, Ni和Ag)光催化剂。利用X-射线衍射(XRD)、程序升温还原(TPR)、红外光谱(IR)、程序升温脱附(TPD)、紫外-可见漫反射光谱(UV-VisDRS)和光反应等技术，研究了负载金属复合半导体的物相结构、吸附性能、吸光性能和光催化反应性能。结果表明，金属M(M=Pd, Cu)负载在复合半导体上，延迟了TiO2由锐钛矿向金红石相的转化，增强了Mo与载体TiO2的相互作用，促进Mo物种由四面体配位向八面体配位转化，使TiO2光吸收限发生蓝移，对可见光部分的吸收明显增加，拓宽了催化剂的光响应范围；固体材料吸光性能强弱顺序Pd/MoO3-TiO2 >Cu/MoO3-TiO2>Ag/MoO3-TiO2>Ni/MoO3-TiO2；Pd对CO2吸附能力过强，卧式吸附态脱附温度高，光催化效率不高；金属Cu对CO2吸附能力适中，CO2与C3H6脱附温度较接近，实现了光-表面-热的协同作用，光量子效率最高。

Effects of loaded metal on structure and photocatalytic performance of photocatalyst for MAA synthesis from propylene and carbon dioxide

M/MoO3-TiO2(M=Pd, Cu, Ni, Ag) photocatalysts were prepared by sol-gel and impregnation-reaction method. The surface structure, adsorption property, photo absorption performance and photo catalytic performance of M/MoO3-TiO2 catalysts were characterized by XRD, TPR, IR, TPD, UV-VisDRS and photoreaction techniques. The experiment results showed that the supported metallic M (M=Pd, Cu) on coupled semiconductor MoO3-TiO2 restrains TiO2 transformation from anatase to rutile and improves the transformation from the tetrahedrally coordinated Mo oxide species to the octahedrally coordinated Mo oxide species. The blue shifting of photo absorption edge and increasing of the photo absorption capacity to visible light were observed clearly after the addition of metallic M (M=Pd, Cu, Ag) on the surface of MoO3-TiO2. The photo absorption decreases in the order of Pd/MoO3-TiO2, Cu/MoO3-TiO2, Ag/MoO3-TiO2 and Ni/MoO3-TiO2. It can be concluded that the adsorption of CO2 on Pd/MoO3-TiO2 is very strong, and its desorption temperature of horizontal adsorption state increases, thus its photo quantum efficiency is lower than that of Cu/MoO3-TiO2, on which desorption temperature for both CO2 and C3H6 is about the same. Loaded metallic Cu realizes “photo-surface-thermal” synergistic effects and improves photo quantum yield.