Surfactant-free Ultrasonication-assisted Synthesis of 2d Tellurium Based on Metastable 1T'-MoTe 2 .

Elemental two-dimensional materials (E2DMs) have been attracting considerable attention owing to their chemical simplicity and excellent/exotic properties. However, the lack of robust chemical synthetic methods seriously limits their potential. Here, we report a surfactant-free liquid-phase synthesis of high-quality 2D tellurium based on ultrasonication-assisted exfoliation of metastable 1T'-MoTe 2 . The as-grown 2D tellurium nanosheets exhibit excellent single crystallinity, ideal 2D morphology, surfactant-free surface, and negligible 1D by-products. Furthermore, a unique growth mechanism based on the atomic escape of Te atoms from metastable transition metal dichalcogenides and guided 2D growth in the liquid phase was proposed and verified. 2D tellurium-based field-effect transistors show ultrahigh hole mobility exceeding 1000 cm 2 ·V -1 ·s -1 at room temperature attributing to the high crystallinity and surfactant-free surface, and exceptional chemical and operational stability using both solid-state dielectric and liquid-state electrical double layer. The facile ultrasonication-assisted synthesis of high-quality 2D tellurium paves the way for further exploration of E2DMs and expands the scope of liquid-phase exfoliation (LPE) methodology towards the controlled wet-chemical synthesis of functional nanomaterials. This article is protected by copyright. All rights reserved.