Electron-Withdrawing Effect of Native Terminal Groups on the Lattice Structure of Ti3C2Tx MXenes Studied by Resonance Raman Scattering: Implications for Embedding MXenes in Electronic Composites

MXenes comprise a class of 2D materials with attractive properties for use in electronically functional composites. However, a fundamental understanding of these properties at the scale of individual flakes is necessary. Here, we use resonance Raman scattering of Ti3C2Tx MXenes to study their vibrational modes as a function of the flake thickness and surface terminations. Enhancement enables a precise comparison of the peak shifts in MILD/HF-method etching environments that produce different functional group densities on the MXene layer surfaces. We find that the enhanced Raman modes are sensitive to the different electron-withdrawing character of the surface functional groups.