三嗪共价骨架(CTF)材料是一类由三嗪环连接构筑的结晶性二维骨架材料, 于光催化领域受到了越来越多的关注. 由于其特殊的二维结构, 各层之间通过非化学键的方式进行堆叠形成体相结构, 因此其各层之间的相互作用力较弱. 在形成骨架过程以及光催化过程中可能发生堆积方式的变化. 然而目前CTFs材料产生层间位错的机理尚未有所研究. 因此本工作采用密度泛函方法, 探究了四种三嗪骨架材料(CTF-1、CTF-2、CTF-13以及CTF-133)的层间位错行为的主要影响因素. 结果表明, 四种CTF发生层间位错行为的过程均为一自发行为, 是由于相邻两层之间三嗪环基团中氮原子上π电子斥力造成的, 而苯环单元的层间堆积能够稳定层间构型. 最后, 对不同堆积方式的CTF-1骨架的光生载流子动力学进行了研究, 发现AA堆积的CTF-1骨架材料具有合适的带隙以及光生载流子迁移速率, 是一种潜在的半导体光催化剂.

Covalent triazine frameworks (CTFs) represent a class of crystalline two-dimensional materials constructed by the interconnection of triazine rings. These materials are increasingly recognized for their potentials in photocatalysis due to their tunable functionality, adjustable bandgap, and structural stability. However, the inherent two-dimensional nature of these frameworks results in stacking through non-covalent interactions between layers, which means that the interlayer forces are relatively weak. This characteristic introduces the possibility of variations in stacking arrangements during both the framework formation process and its subsequent photocatalytic applications. Such variations in stacking can significantly impact the photocatalytic performance by altering its light absorption properties, exciton excitation, and migration characteristics, which, in turn, affect the photocatalytic dynamics of the material. Currently, the mechanisms underlying the formation of interlayer displacements in CTFs have not been extensively studied. Moreover, the influence of different displacement behaviors on the photocatalytic carrier dynamics within these frameworks remains underexplored and not well understood. To address this gap, this study employs density functional theory (DFT) to investigate the key factors influencing interlayer displacement behaviors in four types of CTFs: CTF-1, CTF-2, CTF-13, and CTF-133. The findings reveal that the process of interlayer displacement in these CTFs is a spontaneous process. Through analyses of electronic localization functions and charge density distributions, it was determined that the displacement is primarily caused by repulsive π-electron interactions on the nitrogen atoms within the triazine rings of adjacent layers. This repulsion creates a tendency for layer displacement, while the stacking of benzene ring units serves to stabilize the interlayer arrangement. Additionally, the study explores the photocatalytic carrier dynamics of CTF-1 frameworks with various stacking configurations. The results demonstrate that the CTF-1 frameworks with AA-stacking mode exhibits an optimal bandgap and carrier migration rate, positioning it as a promising candidate for use as a semiconductor photocatalyst. This study investigates the interlayer displacement behavior of triazine-based covalent organic framework materials from a microscopic perspective, and will provide theoretical insights and a basis for the design of novel catalysts based on CTFs.