Ⅱ型范德华异质结g-C6N6/GaTe光催化剂的第一性原理研究

First-Principles Study on the Type Ⅱ Van Der Waals Heterojunction g-C6N6/GaTe Photocatalyst

摘要:

二维材料因其独特的物理性质在光催化领域备受关注，通过构建异质结是提高二维材料光催化性能的有效策略。基于密度泛函理论，采用第一性原理方法系统研究了g-C₆N₆/GaTe范德华异质结的光催化性质。计算结果表明：g-C₆N₆/GaTe的晶格失配率为0.6%，形成能为-486 eV，异质结构稳定；异质结是带隙值为1.45 eV的间接带隙材料，形成稳定的能带交错排列，价带和导带的能带偏置分别为0.56和1.54 eV，同时在界面处生成由g-C₆N₆指向GaTe的内置电场，构成典型的Ⅱ型异质结构。在内置电场和带偏作用下，有利于光生电子-空穴对的有效分离，提高异质结的光催化性能。异质结在可见光范围内的光吸收系数高达约7×10⁴ cm^-1，制氢转换效率为16.48%，有利于光解水反应。最后，尝试对异质结施加载荷，在拉伸应力作用下异质结有明显的红移显现。g-C₆N₆/GaTe异质结是一种具有应用前景的光催化剂，该研究结果为g-C₆N₆/GaTe异质结的设计和制备提供了理论基础。

Abstract:

Two-dimensional materials have attracted much attention in the field of photocatalysis due to their unique physical properties， and constructing heterojunctions is an effective strategy to improve the photocatalytic performance of two-dimensional materials. The photocatalytic properties of g-C₆N₆/GaTe van der Waals heterojunctions have been systematically investigated based on density functional theory. The calculated results show that the lattice mismatch ratio of g-C₆N₆/GaTe is 0.6%， the formation energy is -486 eV and the heterostructure is stable. The heterojunction is an indirect band gap material with a band gap value of 1.45 eV， forming a stable interlaced arrangement of energy bands with an energy band bias of 0.56 eV and 1.54 eV in the valence and conduction bands， respectively. The built-in electric field pointing to GaTe constitutes a typical type II heterostructure. Under the action of the built-in electric field and band polarization， it is conducive to the effective separation of photogenerated electron-hole pairs and improves the photocatalytic performance of the heterojunction. The light absorption coefficient of the heterojunction in the visible light range is as high as 7×10⁴ cm^-1， and conversion efficiency of the hydrogen production is 16.48%， which is favorable for the photolysis of water. Finally， an attempt was made to apply a load to the heterojunction， the heterojunction shows a clear red shift under tensile stress. g-C₆N₆/GaTe Heterojunction is a promising photocatalyst， and the results of this study provide a theoretical basis for the design and preparation of g-C₆N₆/GaTe heterojunction.