Abstract

Graphite-like carbon nitride (g-C₃N₄) nanopowders were synthesized by heat treatment of urea in air at a temperature of 450–550°С for 30 min and studied by X-ray diffraction and infrared spectroscopy. The main processes resulting in the formation of g-C₃N₄ from urea under the above conditions was established using the method of simultaneous thermal analysis. It was found that with an increase in the processing temperature of urea from 450 to 550°C, a rise in the specific surface of the powders occurs from 43.3 to 58.6 m² g^–1, as well as an increase in the crystallite sizes of graphite-like carbon nitride in the crystallographic direction (002) from 2.8 to 4.1 nm. According to the results of scanning electron microscopy and low-temperature nitrogen adsorption, the obtained graphite-like carbon nitride powders have a mesoporous structure and are characterized by an average pore size of 6.6–13.8 nm and porosity of 0.07–0.20 cm³ g^–1. According to the results of diffuse reflectance spectroscopy, it was found that g-C₃N₄ nanopowders absorb radiation in the visible region and have a band gap of 2.9 eV. The photocatalytic activity of the obtained graphite-like carbon nitride during the oxidation of an aqueous murexide solution under the influence of visible light was analyzed and it was shown that the obtained g-C₃N₄ nanopowders have activity close to that of the commercial TiO₂ photocatalyst (AEROXIDE P25). In view of the high activity and low cost, the obtained powders of graphite-like carbon nitride can be used as the substrate for new photocatalytic materials.

中文翻译：

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石墨状氮化碳纳米粉的合成及可见光催化活性

摘要

通过尿素在空气中于450–550°С的温度下进行30分钟的热处理，合成了石墨状的氮化碳（gC ₃ N ₄）纳米粉，并通过X射线衍射和红外光谱进行了研究。使用同时热分析的方法，建立了在上述条件下由尿素生成gC ₃ N ₄的主要过程。研究发现，随着尿素的加工温度从450升高到550°C，粉末比表面积从43.3升高到58.6 m ² g ^–1，以及类石墨氮化碳在晶体学方向（002）上的微晶尺寸从2.8 nm增加到4.1 nm。根据扫描电子显微镜和低温氮吸附的结果，获得的类石墨氮化碳粉末具有中孔结构，其特征是平均孔径为6.6–13.8 nm，孔隙率为0.07–0.20 cm ³ g ^{– 1}。根据漫反射光谱法的结果，发现gC ₃ N ₄纳米粉末吸收可见光区域的辐射，其带隙为2.9 eV。分析了得到的石墨状氮化碳在可见光影响下的无水硫脲水溶液氧化过程中的光催化活性，结果表明，所得到的gC ₃ N ₄纳米粉体的活性接近于商用TiO ₂光催化剂。 （AEROXIDE P25）。鉴于其高活性和低成本，所得的类石墨氮化碳粉末可以用作新型光催化材料的基材。