Metallic edge states in zig-zag vertically-oriented MoS₂ nanowalls

The remarkable properties of layered materials such as MoS₂ strongly depend on their dimensionality. Beyond manipulating their dimensions, it has been predicted that the electronic properties of MoS₂ can also be tailored by carefully selecting the type of edge sites exposed. However, achieving full control over the type of exposed edge sites while simultaneously modifying the dimensionality of the nanostructures is highly challenging. Here we adopt a top-down approach based on focus ion beam in order to selectively pattern the exposed edge sites. This strategy allows us to select either the armchair (AC) or the zig-zag (ZZ) edges in the MoS₂ nanostructures, as confirmed by high-resolution transmission electron microscopy measurements. The edge-type dependence of the local electronic properties in these MoS₂ nanostructures is studied by means of electron energy-loss spectroscopy measurements. This way, we demonstrate that the ZZ-MoS₂ nanostructures exhibit clear fingerprints of their predicted metallic character. Our results pave the way towards novel approaches for the design and fabrication of more complex nanostructures based on MoS₂ and related layered materials for applications in fields such as electronics, optoelectronics, photovoltaics, and photocatalysts.