Ti3C2Tx MXene as a surface-enhanced Raman scattering substrate

Surface-enhanced Raman scattering (SERS) of R6G molecule near Ti3C2Tx MXene flakes is analyzed theoretically. The flakes are modeled as nanoparticles of different shape and size. In order to determine the enhancement factor (EF) of SERS the dye molecule is modeled as a small sphere with polarizability spectrum based on experimental data. In the wavelength range 500 nm − 1000 nm the main contribution to SERS in the case of MXene substrate comes frompolarization induced by two mechanisms - interband transitions (IBT), longitudinal quadrupole and transversal quadrupole surface plasmon (LQSP and TQSP) resonances. We show that both polarization mechanisms present low sensitivity to the shape and size of MXene flakes, which makes it advantageous to use these 2D materials for manufacturing of SERS substrates. The electromagnetic SERS enhancement is determined by the “lightning rod” and “hot-spot” effects due to partial overlapping of absorption spectrum of the R6G molecule with these MXeneresonances. Good agreement between the calculated values of the EF and experimental data of Ti3C2Tx substrate is reached.