Raman Spectroscopy of Dispersive Two-Dimensional Materials: A Systematic Study on MoS₂Solution

Two-dimensional (2D) material solution attracts intense attention from the fields of energy, healthcare, and electronics. Raman spectroscopy is a versatile tool for studying the properties of 2D materials. Despite the numerous elaborate Raman studies of solid-state 2D materials, few have focused on the solution-phase 2D materials. In this work, we systematically investigated the representative 2D MoS2 solution using angle-resolved polarized Raman spectroscopy, helicity-resolved Raman spectroscopy, and resonant Raman spectroscopy. With careful analysis, we find that the Raman spectra of 2D MoS2 solution feature the distinctively detected forbidden Raman modes, the unique Raman anisotropy, and detailed information of the Raman tensor elements, which are unavailable with commonly studied solid-state 2D MoS2. We further established a theoretical model, considering the random orientation of 2D materials in the solution phase, which applies to all the 2D material solutions. With the systematic Raman characterization of the representative 2D MoS2 solution, we expect it to open up more Raman studies on the abundant 2D material solution families.