Defect-Induced Epitaxial Growth for Efficient Solar Hydrogen Production

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 MoS 2 ribbon on 1D CdS nanowires (NWs) via surface and subsurface defects. The interstitial Cd 0 in the (12̅10) crystal plane of the [0001]-oriented CdS NWs are found to serve as nucleation sites for interatomically bonded [001]-oriented MoS 2, where the perfect lattice match (∼99.7%) between the (101̅1) plane of CdS and the (002)-faceted in-plane MoS 2 result in coaxial MoS 2 ribbon/CdS NWs heterojunction. The coaxial but heterotropic epitaxial MoS 2 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 MoS 2 as hydrogen evolution cocatalyst exhibits a ∼10-fold H 2 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.