Upper and Lower Limits of Thermal Diffusivity for Ti3C2Tx MXene Fiber

Transition metal carbides and nitrides (MXenes), a family of two-dimensional materials, exhibit exceptional promise for energy storage applications due to their tunable structural and electrical properties. However, the pronounced adsorption properties inherent to their layered structure complicate the accurate characterization of their thermophysical properties. Here, we systematically investigate the thermal diffusivity of one-dimensional Ti₃C₂T_x MXene fibers using a transient electrothermal method under controlled electrical currents and vacuum environments. Our results reveal a strong correlation between the electrical and thermal responses of Ti₃C₂T_x MXene fibers during heating cycles. As heating progresses, the rate of voltage rise decreases, and the logarithm of the transient voltage response exhibits a robust linear dependence on time, enabling consistent extraction of thermal diffusivity. The thermal diffusivity fluctuates within experimentally determined upper and lower limits, corresponding to the degree of adsorption and desorption of water molecules, quantified at 3.6 × 10⁻⁵ m²·s⁻¹ and 1.0 × 10⁻⁶ m²·s⁻¹, respectively. By refining the understanding of MXene’s thermophysical behavior, this work provides critical insights for optimizing their energy applications and advancing materials with variable physical properties.