硫氰酸铵辅助双氰胺制备g-C3N4及其光催化性能研究-中国材料进展

文章信息/Info

Title:: Preparation of g-C3 N4 with Dicyandiamide Assisted by Ammonium Thiocyanate and Its Photocatalytic Performance

Author(s):: REN Xuechang; SHI Qiuhong; ZHANG Yujie; YANG Linhai; ZHANG Xi; School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China

Keywords:: photocatalysis; dicyandiamide; ammonium thiocyanate; heterojunction; rhodamine B

摘要:: 以双氰胺和硫氰酸铵为前驱体, 将它们按照不同的质量比混合, 600 ℃ 高温煅烧制备g-C3 N4 同型异质结复合材料光催化剂。采用X 射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅立叶红外光谱仪(FTIR)、紫外-可见漫反射吸收光谱仪(UV-vis DRS)等对制备的材料进行了表征分析。以罗丹明B 为模拟污染物, 考察了制备的g-C3N4 在可见光(λ>420 nm)下的催化活性及循环利用稳定性。通过活性物种捕捉实验探寻其降解机理, 结果表明, 双氰胺与硫氰酸铵按3∶ 2 混合制备的 g-C3 N4 的光催化降解罗丹明B 的效率2 h 达到了92. 53%, 是纯双氰胺制备的g-C3 N4 的1. 35 倍, 是纯硫氰酸铵制备的g-C3 N4的1. 75 倍。以双氰胺和硫氰酸铵为前驱体制备的g-C3 N4 是同型异质结, 提高了光生载流子的分离效率, 活性物种捕捉实验表明对催化活性起主要作用的是超氧自由基(·O2 - )。

Abstract:: Graphite phase carbon nitride heterojunction composites were prepared by calcination at 600 ℃ with dicyandiamide and ammonium thiocyanate as precursor. The materials were characterized by X-ray diffractometer (XRD),scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and UV-visible diffuse reflectance absorption spectrum (UV-vis DRS). The catalytic activity of g-C3N4 under visible light (λ>420 nm) and the recycling stability were investigated using rhodamine B (RhB) as a simulated pollutant. The degradation mechanism was explored by the active species capture experiment. The results showed that the photocatalytic degradation efficiency of g-C3N4 prepared by the mixture of dicyandiamide and ammonium thiocyanate at a ratio of 3∶2 reached 92. 53% in 2 h, which was 1. 35 times that of g-C3N4 prepared by pure dicyandiamide and 1. 75 times that of g-C3N4 prepared by pure ammonium thiocyanate. The g-C3N4 prepared by dicyandiamide and ammonium thiocyanate as precursor is a homotype heterojunction, which improves the separation efficiency of photogenerated carriers. The active species capture experiment showed that the superoxide radical (·O2- ) plays a major role in catalytic activity.