Size Selection and Size‐Dependent Optoelectronic and Electrochemical Properties of 2D Titanium Carbide (Ti3C2Tx) MXene

Abstract 2D materials produced via liquid‐phase exfoliation commonly exhibit broad size and thickness distributions, where size selection is required to obtain nanosheets with desired dimensions and properties. Here, size selection of 2D Ti 3 C 2 T x MXene is systematically performed using liquid cascade centrifugation (LCC) and sedimentation‐based separation (SBS) techniques. Based on statistical atomic force and electron microscopy analyses, it is found that the SBS technique offers stronger separation power compared to the LCC technique with an expense of lower yield. Moreover, predominantly monolayer MXene flakes are obtained after centrifugation at low speeds (≤ 3000 rpm) for 15 min for both techniques. Films fabricated from large MXene flakes with the average flake length of 4.2 µm show high electrical figure of merit of 7.8 and improved rate performance as a cathode in Zn‐ion capacitor. This work serves as a guideline for choosing size selection techniques and conditions for MXene processing to obtain flakes with certain sizes and desired properties.