MOF衍生的多孔ZnO/C、Ag/ZnO/C复合材料光催化性能研究

Photocatalytic Properties of MOF-derived ZnO/C, Ag/ZnO/C Porous Composite Materials

以金属有机骨架(MOF-5)为前驱体,通过高温热处理和湿化学法获得ZnO/C和Ag/ZnO/C两种光催化复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDS)和紫外-可见分光漫反射(UV-Vis DRS)等方法对所得样品的晶体结构、形貌特征、组成及光谱特性进行了表征。结果显示,高温热处理保留了MOF-5的原始结构。ZnO/C比表面积为390 m^2/g,载银后比表面积仍达232 m^2/g,负载的银颗粒尺寸约30 nm。光催化降解实验表明ZnO/C和Ag/ZnO/C复合材料对亚甲基蓝(MB)都具有很高的降解效率,均优于商业TiO_2。Ag/ZnO/C的光催化性能更好,且具有较好的重复利用和稳定性。因此,适度的高温碳化和掺杂贵金属是获得优良光催化性能的根本原因。

Two photocatalytic materials, ZnO/C and Ag/ZnO/C, were synthesized by high temperature heat-treatment and wet-chemical methods using a typical metal-organic framework （MOF-5） as precursor. The samples were characterized by X-ray diffraction （XRD）, Scanning electron microscope （SEM）, X-ray energy dispersive spectroscope （EDS）, and UV-Vis diffuse reflection spectroscope （UV-Vis DRS）, respectively. After heat-treatment under nitrogen, the initial morphology of MOF-5 is mostly retained. As a result, relatively high surface area up to 390 mE/g of ZnO/C and 232 m^2/g of Ag/ZnO/C are realized. The size of Ag particles loaded on Ag/ZnO/C is about 30 nm. The photocatalytic efficiencies of both ZnO/C and Ag/ZnO/C composites on photo-degradation of methylene blue （MB） are higher than that of commercial TiO2 powder （Degussa P25）. Ag/ZnO/C possesses even higher photocatalytic ability, repeat- ability and stability than does ZnO/C. The results strongly suggest that high temperature heat-treatment of the MOF properly followed by moderate silver doping is a facile way to improve the photocatalytic properties.