Influence of High Temperature Synthesis on the Structure of Graphitic Carbon Nitride and Its Hydrogen Generation Ability
Influence of High Temperature Synthesis on the Structure of Graphitic Carbon Nitride and Its Hydrogen Generation Ability
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DOI：
10.3390/ma13122756
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发表时间：
2020-06-01
期刊：
影响因子：
3.4
通讯作者：
Pietrowski, Mariusz
中科院分区：
文献类型：
--
作者：
Alwin, Emilia;Koci, Kamila;Pietrowski, Mariusz
石墨碳氮化物（g-C3 N4）通过双氰胺、硫脲或三聚氰胺在高温（550和600 ℃）下使用不同的加热速率（2或10 ℃ min（-1））和合成时间（0或4 h）进行热聚合而获得。研究了合成条件和前驱体种类对g-C（3）N（4）合成效率的影响。以双氰胺为原料的合成效率最高，为53%，而以三聚氰胺和硫脲为原料的合成效率要低得多，分别为26%和11%。通过X射线衍射（XRD）、X射线光电子能谱（XPS）、红外光谱（FTIR）、紫外-可见光谱（UV-vis）、热重分析（TGA）、元素分析（EA）等测试手段，确定了合成g-C（3）N（4）的最佳前驱体和最佳条件，得到了结构最稳定的产物，结构的有序化和缩合程度最高，最终光催化活性最高。结果表明，随着质子浓度的降低和缩合度的增加，水-甲醇溶液光催化分解过程中的氢气产率显着提高。氢的生成量为1200 μ mol·g ~（-1），对氢的选择性大于98%。
Graphitic carbon nitride (g-C3N4) was obtained by thermal polymerization of dicyandiamide, thiourea or melamine at high temperatures (550 and 600 degrees C), using different heating rates (2 or 10 degrees C min(-1)) and synthesis times (0 or 4 h). The effects of the synthesis conditions and type of the precursor on the efficiency of g-C(3)N(4)were studied. The most efficient was the synthesis from dicyandiamide, 53%, while the efficiency in the process of synthesis from melamine and thiourea were much smaller, 26% and 11%, respectively. On the basis of the results provided by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), thermogravimetric analysis (TGA), elemental analysis (EA), the best precursor and the optimum conditions of synthesis of g-C(3)N(4)were identified to get the product of the most stable structure, the highest degree of ordering and condensation of structure and finally the highest photocatalytic activity. It was found that as the proton concentration decreased and the degree of condensation increased, the hydrogen yields during the photocatalytic decomposition of water-methanol solution were significantly enhanced. The generation of hydrogen was 1200 mu mol g(-1)and the selectivity towards hydrogen of more than 98%.