Violation of the Wiedemann-Franz Law and Ultralow Thermal Conductivity of TiCT MXene.

The high electrical conductivity and good chemical stability of MXenes offer hopes for their use in many applications, such as wearable electronics, energy storage, and electromagnetic interference shielding. While their optical, electronic, and electrochemical properties have been widely studied, information on the thermal properties of MXenes is scarce. In this study, we investigate the heat transport properties of TiCT MXene single flakes using scanning thermal microscopy and find exceptionally low anisotropic thermal conductivities within the TiCT flakes, leading to an effective thermal conductivity of 0.