从三嗪到庚嗪：石墨碳氮化物作为光催化剂的起源。,ACS Omega

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从三嗪到庚嗪：石墨碳氮化物作为光催化剂的起源。
ACS Omega ( IF 4.1 ) Pub Date : 2020-05-18 , DOI: 10.1021/acsomega.0c01607
Nan Liu ₁ , Tong Li ₁ , Ziqiong Zhao ₁ , Jing Liu ₁ , Xiaoguang Luo ₂ , Xiaohong Yuan ₃ , Kun Luo _{1,

4} , Julong He ₁ , Dongli Yu ₁ , Yuanchun Zhao ₁

Affiliation

石墨碳氮化物（g-CN）已经成为一种有前途的无金属光催化剂，而光诱导氧化还原过程的催化机理仍在研究中。有趣的是，这种基于庚嗪的聚合物在光学上表现为“准单体”。在这项工作中，我们探索了从me烯（庚嗪单体）到基于三嗪的三聚氰胺和蜜胺的上游，并提供了一些理论/实验证据，其中g-CN的催化活性源自C–N的电子结构演变。杂环核。周期性密度泛函理论计算揭示了与基于三嗪的对映体不同的蜜胺电子结构。傅里叶变换红外光谱和X射线光电子能谱在这三种相关化合物的结构和化学键变化方面也提供了一致的结果。研究发现，在紫外线-可见光照射下，降解染料过程中，melam和melem均显示出稳定的光催化活性，而melem的光催化活性约为melam的5.4倍。与蜜胺和蜜胺相反，蜜胺中庚嗪单元的前沿电子轨道是均匀分布的并且彼此很好地互补，这进一步确定了末端胺是主要的还原位点。杂环骨架和端接的官能团中的这些引人注目的电子特征可以由聚合但准单体的g-CN继承，

"点击查看英文标题和摘要"

From Triazine to Heptazine: Origin of Graphitic Carbon Nitride as a Photocatalyst.

Graphitic carbon nitride (g-CN) has emerged as a promising metal-free photocatalyst, while the catalytic mechanism for the photoinduced redox processes is still under investigation. Interestingly, this heptazine-based polymer optically behaves as a “quasi-monomer”. In this work, we explore upstream from melem (the heptazine monomer) to the triazine-based melamine and melam and present several lines of theoretical/experimental evidence where the catalytic activity of g-CN originates from the electronic structure evolution of the C–N heterocyclic cores. Periodic density functional theory calculations reveal the strikingly different electronic structures of melem from its triazine-based counterparts. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy also provide consistent results in the structural and chemical bonding variations of these three relevant compounds. Both melam and melem were found to show stable photocatalytic activities, while the photocatalytic activity of melem is about 5.4 times higher than that of melam during the degradation of dyes under UV–visible light irradiation. In contrast to melamine and melam, the frontier electronic orbitals of the heptazine unit in melem are uniformly distributed and well complementary to each other, which further determine the terminal amines as primary reduction sites. These appealing electronic features in both the heterocyclic skeleton and the terminated functional groups can be inherited by the polymeric but quasi-monomeric g-CN, leading to its pronounced photocatalytic activity.

更新日期：2020-05-18

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