Enhanced Thermoelectric Properties of Ti₂CO₂–Bismuthene–Ti₂CO₂: Optimized Power Factor and Reduced Thermal Conductivity

In this study, bismuthene was intercalated between bilayer Ti₂CTx 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 Ti₂CO₂ system from a semiconductor into a metal and optimizes the thermoelectric properties of bilayer Ti₂CO₂ 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 Ti₂CO₂ 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 Ti₂C system and from 0.07 to 0.05 in the Ti₂CCl₂ 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.