Graphitic carbon nitride (g-C3N4)-based materials have attracted interdisciplinary attention from many fields. However, their crystal structures have not yet been described well. Poly(triazine imide)/LiCl (PTI/LiCl) of good crystallinity synthesized from salt melts enables a confident structural solution for a better understanding of g-C3N4-based materials. In this study, we synthesize PTI/LiCl of high crystallinity in air without byproducts and confirm the orthorhombic feature, which is not observed in powder X-ray diffraction (PXRD) patterns at room temperature, by employing low-temperature synchrotron PXRD. Together with spectroscopic techniques (X-ray photoelectron spectroscopy, solid-state nuclear magnetic resonance, and Fourier-transform infrared/Raman), the orthorhombic structure (space group Cmc21, No. 36) was determined and found to be a superstructure of the previously reported hexagonal structure, as confirmed by electron diffraction. The temperature-dependent synchrotron PXRD data also reveal a highly anisotropic expansion. This work also shows the much higher activity of PTI/LiCl than of g-C3N4 for the photocatalytic degradation of methyl orange under ultraviolet irradiation, especially so for PTI/LiCl with a densely packed (001) plane. This study demonstrates the structural complexity of the g-C3N4 class of materials and illustrates how their temperature-dependent anisotropies facilitate the discovery of the structural features in resolving the structure of g-C3N4-related materials and their structure-property relationship.

中文翻译：

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揭开聚三嗪酰亚胺/ LiCl光催化剂的结构：轻松合成和低温同步加速器方法的合作。

石墨碳氮化物（g-C3N4）基材料已吸引了许多领域的跨学科关注。然而，它们的晶体结构尚未被很好地描述。由盐熔体合成的具有良好结晶度的聚（三嗪酰亚胺）/ LiCl（PTI / LiCl）可提供令人信服的结构解决方案，以更好地理解基于g-C3N4的材料。在这项研究中，我们在空气中合成了高结晶度的PTI / LiCl，没有副产物，并通过使用低温同步加速器PXRD证实了在室温下粉末X射线衍射（PXRD）模式中未观察到的正交晶体特征。结合光谱技术（X射线光电子能谱，固态核磁共振和傅立叶变换红外/拉曼光谱），正交结构（空间群Cmc21，No。如通过电子衍射所证实的，确定36）是先前报道的六边形结构的上层结构。随温度变化的同步加速器PXRD数据还显示出高度各向异性的膨胀。这项工作还表明，PTI / LiCl在紫外线照射下对甲基橙的光催化降解活性比g-C3N4高得多，尤其是对于具有密集堆积（001）平面的PTI / LiCl。这项研究证明了g-C3N4类材料的结构复杂性，并说明了它们的温度依赖性各向异性如何促进解析g-C3N4相关材料的结构及其结构-性质关系的结构特征的发现。随温度变化的同步加速器PXRD数据还显示出高度各向异性的膨胀。这项工作还表明，PTI / LiCl在紫外线照射下对甲基橙的光催化降解活性比g-C3N4高得多，尤其是对于具有密集堆积（001）平面的PTI / LiCl。这项研究证明了g-C3N4类材料的结构复杂性，并说明了它们的温度依赖性各向异性如何促进解析g-C3N4相关材料的结构及其结构-性质关系的结构特征的发现。随温度变化的同步加速器PXRD数据还显示出高度各向异性的膨胀。这项工作还表明，PTI / LiCl在紫外线照射下对甲基橙的光催化降解活性比g-C3N4高得多，尤其是对于具有密集堆积（001）平面的PTI / LiCl。这项研究证明了g-C3N4类材料的结构复杂性，并说明了它们的温度依赖性各向异性如何促进解析g-C3N4相关材料的结构及其结构-性质关系的结构特征的发现。特别是对于具有密集堆积（001）平面的PTI / LiCl。这项研究证明了g-C3N4类材料的结构复杂性，并说明了它们的温度依赖性各向异性如何促进解析g-C3N4相关材料的结构及其结构-性质关系的结构特征的发现。特别是对于具有密集堆积（001）平面的PTI / LiCl。这项研究证明了g-C3N4类材料的结构复杂性，并说明了它们的温度依赖性各向异性如何促进解析g-C3N4相关材料的结构及其结构-性质关系的结构特征的发现。