Probing Thermal Transport on a Suspended Ti₃C₂T_x MXene Film via a Photothermally Actuated Resonator

Two-dimensional (2D) Ti₃C₂T_x MXene materials show great potential in electrochemical and flexible sensors due to their high electrical conductivity, good chemical stability, and special delaminated structure. However, their thermal properties were rarely studied, which remarkably affect the stability and safety of various devices. Here, we fabricated a suspended MXene drum resonator photothermally driven by a sinusoidally modulated laser, measured the thermal time constant by demodulating the thermomechanical motion, and then calculated the thermal conductivity and thermal diffusivity of the MXene film. Experiments show the thermal conductivity of the film increases from 3.10 to 3.58 W/m·K while the thermal diffusivity from 1.06 × 10^-6 to 1.22 × 10^-6 m²/s when temperature increases from 300 to 360 K. We also confirm the film thermal conductivity is mainly contributed by phonon transport rather than electron transport. Furthermore, the relationship between the mechanical and thermal properties of the MXene films was disclosed. The thermal conductivity decreases when film strain increases, caused by enhanced phonon scattering and softening of high-frequency phonons. The measurements provide a noninvasive method to analyze the thermal characteristics of suspended MXene films, which can be further extended to the thermal properties of other 2D materials.