MoS2–WS2 Heterostructures with Vertical Nanosheets for Enhanced Photocatalytic Hydrogen Generation through Morphology-Controlled Chemical Vapor Deposition

Abstract

Constructing a nanostructure that combines abundant active edge sites with a well-designed heterostructure is an effective strategy for enhancing photocatalytic hydrogen generation. However, controllable approaches for creating heterostructures based on vertically standing transition metal dichalcogenide (TMD) nanosheets remain insufficient despite their potential for efficient hydrogen production. In this paper, we present efficient photocatalysts featuring heterojunctions composed of vertically grown TMD (MoS2 and WS2) nanosheets. These structures (WS2, MoS2, and MoS2/WS2 heterostructure) were fabricated using a controllable metal–organic chemical vapor deposition method, which expanded the surface area and facilitated effective photocatalytic hydrogen evolution. The vertical MoS2/WS2 heterostructures demonstrated significantly enhanced hydrogen generation, driven by the synergistic effects of improved light absorption, a large specific surface area, and appropriately arranged staggered heterojunctions. Furthermore, the photocatalytic activity was considerably influenced by the size and density of the vertical nanosheets. Consequently, the nanosheet size-tailored MoS2/WS2 heterostructure achieved a photocatalytic hydrogen generation rate (454.2 μmol h−1 cm−2), which is 2.02 times and 2.19 times higher than that of WS2 (225.6 μmol h−1 cm−2) and MoS2 (207.2 μmol h−1 cm−2). Hence, the proposed strategy can be used to design staggered heterojunctions with edge-rich nanosheets for photocatalytic applications.