Reconnaissance Peptide Labeling Grain Boundary of Chemically Grown MoS ₂ Polycrystalline Monolayer

ABSTRACT Chemically‐grown large‐size 2D nanomaterial monolayers, such as MoS ₂ , open a great opportunity for on‐demand applications in nano‐optics, nanoelectronics, and nanomagnetics. However, the existence of defects, grain boundaries (GBs) as a representative one, severely affects the performance of MoS ₂ ‐based devices in optics and electronics. Labeling nanoscale‐sized GBs still faces a big challenge, although much greater work for imaging GBs has been reported by electron microscopy, light microscopy, and other techniques. Alternatively, we introduce a simple, rapid, and efficient method, based on surface behaviors of peptide adsorption and aggregation, to label nanoscale GBs of chemically‐grown MoS ₂ polycrystalline monolayers (CG‐MoS ₂ ‐PM). Different peptide sequences (lengths, charges) via peptide binding and assembling show the same labelling abilities, indicating robustness and promising strategies. Besides, both GBs from the polycrystalline monolayer and multiplayer are identified. This work would provide an alternative strategy for examining the quality of CG‐MoS ₂ ‐PM, promoting the potent on‐demand applications of 2D materials‐based nanodevices.