Epitaxial growth suffers from the mismatches in lattice and dangling bonds arising from different crystal structures or unit cell parameters. Here, we demonstrate the epitaxial growth of 2D MoS2 ribbon on 1D CdS nanowires (NWs) via surface and subsurface defects. The interstitial Cd0 in the (12̅10) crystal plane of the [0001]-oriented CdS NWs are found to serve as nucleation sites for interatomically bonded [001]-oriented MoS2, where the perfect lattice match (∼99.7%) between the (101̅1) plane of CdS and the (002)-faceted in-plane MoS2 result in coaxial MoS2 ribbon/CdS NWs heterojunction. The coaxial but heterotropic epitaxial MoS2 ribbon on the surface of CdS NWs induces delocalized interface states that facilitate charge transport and the reduced surface state. A less than 5-fold ribbon width of MoS2 as hydrogen evolution cocatalyst exhibits a ∼10-fold H2 evolution enhancement than state of the art Pt in an acidic electrolyte, and apparent quantum yields of 79.7% at 420 nm, 53.1% at 450 nm, and 9.67% at 520 nm, respectively.
Keywords: Epitaxial growth; MoS2 ribbon; chemically bonded interface; defective surface; hydrogen evolution.