光谱学与光谱分析, 2020, 40 (7): 2159, 网络出版: 2020-12-05  

硝酸辅助合成氮缺陷石墨型氮化碳材料及光谱学分析

Spectroscopic Analysis of Nitric Acid-Assisted Synthesis of Nitrogen-Defected Graphite Carbon Nitride Materials
作者单位
上海理工大学环境与建筑学院, 上海 200093
摘要
通过硝酸辅助高温缩聚三聚氰胺的方法合成了氮缺陷石墨型氮化碳(g-C3N4)光催化材料, 并利用scanning electron microscope (SEM), brunauer emmett teller (BET), X射线衍射(X-ray diffraction, XRD), ultraviolet-visible spectroscopy (UV-Vis), X射线光电子能谱(X-ray photoelectron spectroscopy, XPS)和Fourier transform infrared spectroscopy (FTIR)等手段对其微观结构和光谱学特征进行了分析, SEM给出了氮化碳和改性材料的表面微观形貌, 改性材料表现出了更小的孔径与更加粗糙类似于“矾花”状的表面, 说明硝酸的加入显著改变了材料的表面结构。 BET图谱可以明显看出硝酸辅助合成材料显示出了较大的比表面积和孔径。 XRD图谱显示改性后的材料保持了氮化碳材料的一般结构特征, 并且两个特征峰均发生了峰宽以及角度的变化, 说明了酸辅助可以改变原材料的结构。 从UV-Vis图谱中看出改性材料发生了明显的红移现象, 说明材料对可见光的响应较原始氮化碳材料有一定增强。 FTIR图谱显示改性后材料在保持原有材料基团的基础上碳氮单键以及氨基基团增多等变化。 从XPS图谱中发现改性材料的结合能以及峰面积发生变化, 由此得出N元素含量显著提高, 推测由于三聚氰胺与硝酸产生部分反应后被高温焙烧引入硝酸中的氮元素。 最后测试了材料在可见光和太阳光照射下的催化性能。 结果表明, 该方法不仅简单易行, 硝酸消耗量低, 而且合成的g-C3N4材料具有很好的多孔结构、 更小的粒度和更高的比表面积等微观结构优势, 以及增强的光吸收响应特征, 更重要的是与由其他方法合成材料的碳氮(C/N)比上升不同, 该方法合成的材料C/N比有明显的下降趋势, 氨基基团也有增多的表现, 这可能因硝酸与三聚氰胺在高温烧结过程中的化学反应所导致。 可见光和太阳光照射催化降解罗丹明B(RhB)的试验结果表明, 当硝酸用量为2 mL时g-C3N4材料的催化效果最佳, 降解率均达到99%, 分别是无硝酸条件下的2.8倍和2.5倍, 并且材料的循环性降解测试表明材料的可回收性强。 这种高效易得、 方便工业化推广和可回收性强的g-C3N4材料为今后的实际应用提供了极好的参考。
Abstract
Nitrogen-defective g-C3N4 catalytic materials were synthesized by nitric acid-assisted high-temperature polycondensation of melamine. The microstructure and spectroscopic characteristics were analyzed by scanning electron microscope (SEM), Brunauer Emmett Teller (BET), X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy(FTIR). The modified material of sem images exhibits a smaller pore size and a rougher surface resembling a “flower” shape, indicating that the addition of nitric acid significantly changes the structure of the material. The BET spectrum clearly shows that the nitric acid-assisted synthetic material exhibits a large specific surface area and pore size. The XRD pattern shows that the modified material not only maintains the general structural characteristics of the carbon nitride material, but also changes the peak width and angle at both peaks, indicating that assistance of the acid can change the structure of the raw material. It is seen from the UV-Vis spectrum that the modified material has a significant red shift phenomenon, indicating that the material has a certain enhancement to the visible light compared to the original carbon nitride material. The FTIR spectrum shows that the modified material has a change in the carbon-nitrogen single bond and an increase in the amino group on the basis of maintaining the original material groups. From the image of the XPS spectrum, it was found that the binding energy of the modified material and the peak area changed, and the N element content was significantly improved. It is speculated that the conversion of the melamine caused by the action of nitric acid caused the increase of nitrogen. Finally, the Catalytic performance of the materials was tested under visible light and sunlight. The results show that the method is not only simple, the consumption of nitric acid is also low, and the synthesized g-C3N4 material has better micro-structure advantages such as porous structure, smaller particle size and higher specific surface area, and more importantly, The C/N ratio of the materials synthesized by this method has a significant downward trend, and the amino groups also have an increased performance, which may be caused by the chemical reaction between nitric acid and melamine during high-temperature sintering. The results of catalytic degradation of RhB by visible light and sunlight showed that the catalytic effect of g-C3N4 was the best when the volume of nitric acid was 2 mL, and the degradation rate reached 99%, which was 2.8 times and 2.5 times than non-nitric acid materials, respectively. The cyclic degradation test of the material indicates that the material has high recyclability. This materials which include highly efficient, easy-to-industrial and recyclable provides an excellent reference for future practical applications.

陈闽南, 陶红, 宋晓峰, 王怡心, 邵玲, 韩啸, 刘伟, 殷广艺, 谢心语, 严南峡. 硝酸辅助合成氮缺陷石墨型氮化碳材料及光谱学分析[J]. 光谱学与光谱分析, 2020, 40(7): 2159. CHEN Min-nan, TAO Hong, SONG Xiao-feng, WANG Yi-xin, SHAO Ling, HAN Xiao, LIU Wei, YIN Guang-yi, XIE Xin-yu, YAN Nan-xia. Spectroscopic Analysis of Nitric Acid-Assisted Synthesis of Nitrogen-Defected Graphite Carbon Nitride Materials[J]. Spectroscopy and Spectral Analysis, 2020, 40(7): 2159.

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