一锅法制备Co_3O_4/g-C_3N_4复合光催化剂及其光催化性能

Preparation and Photocatalytic Activity of Co_3O_4/g-C_3N_4 Composite Photocatalysts via One-Pot Synthesis

以三聚氰胺和六水合氯化钴为原料,一锅法制备Co_3O_4负载的多孔石墨相氮化碳(Co_3O_4/g-C_3N_4)复合光催化材料。采用X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光光谱(PL)等手段对其结构和光学特性进行表征。以盐酸四环素(TC)为目标污染物,评价了不同负载量Co_3O_4/g-C_3N_4复合光催化剂的可见光催化性能。结果表明,所制备的Co_3O_4/g-C_3N_4复合光催化剂为多孔结构,其比表面积较大,并在可见光区域具有显著的吸收。利用原位生成的Co_3O_4纳米粒子在氮化碳表面形成异质结构,可有效转移光生载流子,降低光生电子-空穴的再结合率,从而提高光催化活性。并且存在最佳Co_3O_4复合量,当六水合氯化钴加入量为三聚氰胺的8%(w/w)时,所制备的复合光催化剂CoCN-8具有最佳的光催化性能。在可见光的照射下,60 min内可降解85%的TC,而同样条件下,纯g-C_3N_4仅降解23%的TC。

A series of Co3O4/g-C3N4 composite photocatalysts were prepared by a one-pot method using melamine and cobalt chloride hexahydrate as raw materials. The structure and optical properties of the synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectrum (PL). The photocatalytic activities of Co3O4/g-C3N4 composites were evaluated by using tetracycline hydrochloride(TC) as a model pollutant under visible light irradiation. The results indicated that Co3O4/g-C3N4 composite photocatalysts were porous structures with high specific surface area, which have significant light absorption in visible light region. The in-situ generated Co3O4 nanoparticles can form heterojunctions on the surface of g-C3N4, which can effectively transfer the photon-generated carriers and decrease the recombination rate of electrons and holes, thus the photocatalytic activity can be efficiently improved. Besides, there was an optimal amount of Co3O4 for the Co3O4/g-C3N4 composite photocatalysts. When the adding amount of cobalt chloride hexahydrate was 8%(w/w) of melamine, the obtained composite photocatalyst (CoCN-8) showed the highest photocatalytic performance and the degradation of TC can reach 85% within 60 min under visible light irradiation. However, in the same condition, the degradation of TC can only reach 23% by pure g-C3N4 photocatalyst.