Modeling the 2D Van der Waals (vdW) heterostructure photocatalysts is an effective way to take advantage of solar energy and suppressing the fast recombination rate of photo-generated charge carriers. In the present work, we have systematically investigated the electronic, optical and photocatalytic properties of the GaS/BTe vdW heterostructure under an applied external electric field using first-principles calculations. Our results reveal that the GaS/BTe vdW heterostructure has an indirect band gap of 1.06/1.59 eV with PBE/HSE06 functional without electric field. The results also imply that electrons are likely to transfer from GaS to BTe monolayer due to the deeper potential of BTe monolayer. The GaS/BTe vdW system forms a type-II band alignment and established a large electric field at the interface, controlling to effective separation of the electron–hole pairs. Also, the transverse external electric considerably changes the band gap and transform from type-II to type-I and type-III band alignments. The GaS/BTe vdW heterostructure, also enhanced the optical absorption as compared to pristine GaS and BTe monolayer. Furthermore, the ($-$)ve electric field significantly increases the optical absorption spectrum in infrared (IR) to visible region, while the (+)ve electric field enhances the optical absorption coefficients in visible to ultraviolet (UV) region. The external transverse electric field enhances the hydrogen evolution reaction (HER) activity on the 2D vdW heterostructure. These obtained results predict that the 2D GaS/BTe vdW heterostructures carry potential applications to enhancing the photocatalytic performance under visible light irradiation.

对2D Van der Waals（vdW）异质结构光催化剂进行建模是一种利用太阳能并抑制光生电荷载流子快速重组速率的有效方法。在目前的工作中，我们使用第一性原理系统地研究了外加电场下GaS / BTe vdW异质结构的电子，光学和光催化性能。我们的结果表明，GaS / BTe vdW异质结构具有1.06 / 1.59 eV的间接带隙，具有PBE / HSE06的功能而没有电场。该结果还暗示，由于BTe单层的电势较深，电子很可能从GaS转移到BTe单层。GaS / BTe vdW系统形成II型能带对准并在界面处建立了大电场，控制电子-空穴对的有效分离。而且，横向外部电极大地改变了带隙并且从II型转变为I型和III型带取向。与原始的GaS和BTe单层相比，GaS / BTe vdW异质结构还增强了光吸收。此外，（$-$ve电场显着增加了红外（IR）到可见光区域的光吸收光谱，而（+）ve电场增强了可见光到紫外（UV）区域的光吸收系数。外部横向电场增强了二维vdW异质结构上的氢释放反应（HER）活性。这些获得的结果预测2D GaS / BTe vdW异质结构在增强可见光照射下的光催化性能方面具有潜在的应用前景。