Defect engineering of MoS2/borophene/WS2 sandwich heterostructures enhanced the HER catalytic activity and improved water splitting efficiency

Abstract

To enhance the stability of borophene and improve its catalytic activity for the HER, we have proposed a MoS₂/borophene/WS₂ sandwich structure and have systematically examined the influence of defect morphology on its catalytic properties. Furthermore, the influence of five intrinsic defects on the HER catalytic activity at the interface of the MoS₂/borophene/WS₂ heterojunction has been studied. To estimate the HER catalytic properties of the heterojunction, we calculated the dissociation energy barriers of water molecules over the S-vacancy-containing MoS₂/borophene/WS₂ heterojunction and systematically analyzed the energy barriers with three potential dissociation pathways. The results demonstrate that the MoS₂/borophene/WS₂ sandwich structure substantially improves the stability of the 2D-borophene structure. Note that the MoS₂/borophene/WS₂ heterojunction with S-vacancies exhibited excellent catalytic properties, demonstrated by the calculated ΔG_H* of only −0.01 eV. This value is considerably lower than that of Pt and the borophene/WS₂ heterojunction, highlighting its enhanced catalytic efficiency. In particular, due to the synergistic effect between borophene and defective WS₂, the dissociation energy of water molecules was reduced to 0.71 eV. As a result, we propose that this MoS₂/borophene/WS₂ heterojunction not only demonstrates excellent HER catalytic activity but also effectively lowers the energy barrier for water dissociation in alkaline or neutral conditions. This advancement provides critical support for facilitating the practical application of borophene as an efficient HER catalyst.