Modulation of 2D GaS/BTe vdW heterostructure as an efficient HER catalyst under external electric field influence

Abstract

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.