Halogen‐Mediated Polymer‐Free Recovery of Pristine MoS ₂ Monolayers From Gold‐Assisted Exfoliation

Metal‐assisted mechanical exfoliation has recently emerged as a powerful strategy for producing large‐area monolayers of two‐dimensional (2D) transition‐metal dichalcogenides (TMDs) with near‐intrinsic crystalline quality. The strong adhesion between the TMD monolayer and the metallic adhesion layer poses a significant challenge for device integration, as it generally requires polymer‐assisted transfer processes that introduce contamination, mechanical strain, and structural defects. Here we report a halogen‐mediated biphasic etching strategy that enables the polymer‐free recovery of TMD monolayers directly from gold‐assisted exfoliation substrates. Sequential iodine vapor exposure followed by liquid‐phase iodine etching weakens the Au‐TMD interfacial interaction and subsequently removes the gold adhesion layer while preserving the structural integrity of the monolayer. Spectroscopic characterization, time‐resolved morphological analysis, and first‐principles calculations reveal that iodine adsorption modifies the electronic structure of the Au surface and reduces its binding strength to the TMD layer. MoS 2 monolayers recovered using this approach exhibit significantly reduced strain, lower charge doping, and suppressed wrinkle formation compared with polymer‐transferred counterparts. Optoelectronic devices fabricated from these monolayers demonstrate enhanced photocurrent and improved operational stability. These findings establish halogen‐mediated biphasic etching as a scalable route for integrating pristine 2D semiconductors with technologically relevant substrates and provide a promising pathway toward high‐performance 2D optoelectronic devices.