Enhanced Thermoelectric Properties of TiCO-Bismuthene-TiCO: Optimized Power Factor and Reduced Thermal Conductivity.

In this study, bismuthene was intercalated between bilayer TiCTx to induce significant modifications in its electronic and phonon structures, thereby enhancing its thermoelectric properties. First-principles calculations reveal that the insertion of bismuthene transforms the TiCO system from a semiconductor into a metal and optimizes the thermoelectric properties of bilayer TiCO by enhancing its power factor and reducing its lattice thermal conductivity. Under the first-principles calculation parameters used in this study, the ZT of the TiCO system increased from 0.12 to 0.55. Conversely, for metallic bilayer MXenes, the introduction of bismuthene led to a substantial decrease in ZT (from 0.53 to 0.11 in the TiC system and from 0.07 to 0.05 in the TiCCl system). This study investigates the physical mechanisms underlying the enhancement of thermoelectric properties from both electronic and phononic perspectives and provides theoretical insights into the development and application of MXene-based thermoelectric materials.