In situ construction of a heterojunction over the surface of a sandwich structure semiconductor for highly efficient photocatalytic H2 evolution under visible light irradiation

Abstract

Developing a heterostructure on the surface of a “sandwich” structure semiconductor is essential for full utilization of its heterojunction function and hence for designing efficient solar energy conversion systems. Here, we show that 2D–2D MoS₂/MnSb₂S₄ heterostructure composites are designed for the first time and successfully synthesized by a simple in situ calcination pathway. Under visible light irradiation, the ca. 3.3 wt% MoS₂/MnSb₂S₄ samples exhibited the highest activity for H₂ evolution, which was 7.7 times higher than that of the pristine MnSb₂S₄ monolayer. The outstanding photocatalytic performance was attributed to the MoS₂ nanosheets intimately growing on the surface [SbS]⁺ layers of monolayer MnSb₂S₄ nanosheets with the [SbS]⁺–[MnS₂]²⁻–[SbS]⁺ sandwich substructure to form the 2D–2D MoS₂/MnSb₂S₄ heterojunction structure. More importantly, we prove that this specific heterojunction structure can lead to more weakening of the constraint of the valence electrons in the composited photocatalysts, which can promote the transfer of photogenerated electrons from MnSb₂S₄ to MoS₂. The present study provides a new design strategy for the construction of a heterostructure to improve the photocatalytic H₂ production activity highly efficiently.