g-C_3N_4/BiOBr异质结光催化剂的制备与可见光催化活性

以三聚氰胺作为合成g-C_3N_4纳米片的前躯体,以Bi(NO3)3·5H2O和KBr作为合成BiOBr的原料,采用水热法构建g-C_3N_4/Bi OBr二维异质结可见光催化剂,有效的晶面复合和合适的能带组合有助于增强g-C_3N_4和BiOBr的可见光催化活性。利用X射线衍射(XRD)、透射电镜(TEM)、X射线光电子能谱(XPS)、光致发光光谱(PL)和紫外-可见漫反射光谱(UVvis DRS)等方法表征其结构、光学性质以及组成结构。在可见光(λ420 nm)下以光催化降解RhB来评价合成催化剂的光催化活性,结果表明,g-C_3N_4/BiOBr光催化降解罗丹明B(Rh B)的效率高于单体g-C_3N_4和BiOBr,并对g-C_3N_4/BiOBr增强可见光催化RhB机理进行解释。

Preparation of p-n heterojunction g-C3N4/BiOBr and its photocatalytic performance under visible light

g-C₃N₄ nanosheet was obtained from the precursors melamine and BiOBr nanosheets was synthesized from the raw materials Bi(NO₃)₃·5H₂O and KBr. The two-dimensional g-C₃N₄/BiOBr heterojunction was synthesized by hydrothermal method. The intimated interface and suitable crystal facets of g-C₃N₄ and BiOBr were favorable the combination of this two photocatalysts, resulting in enhancing the visible-light photocatalytic activity. The phase structure, optical absorption property as well as composition and structure of as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflection spectroscopy (DRS) and photoluminescence emission spectroscopy. The potential mechanisms of constructing two-dimensional g-C₃N₄/BiOBr heterojunction were revealed. The photocatalytic activity of as-synthesized photocatalysts was evaluated by photocatalytic degradation of RhB under visible light (λ>420 nm) irradiation. Results show that the as-synthesized heterojunctions can significantly enhance photocatalytic activity in comparison with pure g-C₃N₄ and BiOBr. The mechanisms of enhanced photocatalytic performance were explained.