Stiffer Bonding of Armchair Edge in Single-Layer Molybdenum Disulfide Nanoribbons

The physical and chemical properties of nanoribbon edges are important for characterizing nanoribbons and applying them in electronic devices, sensors, and catalysts. The mechanical response of molybdenum disulfide nanoribbons, which is an important issue for their application in thin resonators, is expected to be affected by the edge structure, albeit this result is not yet being reported. In this work, the width-dependent Young's modulus is precisely measured in single-layer molybdenum disulfide nanoribbons with armchair edges using the developed nanomechanical measurement based on a transmission electron microscope. The Young's modulus remains constant at ≈166 GPa above 3 nm width, but is inversely proportional to the width below 3 nm, suggesting a higher bond stiffness for the armchair edges. Supporting the experimental results, the density functional theory calculations show that buckling causes electron transfer from the Mo atoms at the edges to the S atoms on both sides to increase the Coulomb attraction.