Screening of 225 Double-Transition-Metal o-MXenes for Superior Thermoelectric Property at Room Temperature from First-Principles Electron and Phonon Calculations

The high-throughput workflows are developed to efficiently and reliably predict the electrical and thermal conductivities of double-transition-metal o-MXenes. We conduct the calculations for 225 double-transition-metal o-MXenes with different transition-metal combinations, surface terminations (−H, −F, −O, and −OH), and structural types (“212” and “223”). For all investigated o-MXenes, their electrical conductivities are found to be in the range from 10⁵ up to 10⁷ S/m, indicating that o-MXenes are good electron conductors. With regard to the thermal conductivity, electron thermal conduction dominates the total thermal conductivity for surface functionalized o-MXenes. In the case of intrinsic o-MXenes, lattice thermal conductivity is comparable to that of electron thermal conduction. Surface terminations show great influence on both phonon and electron transport properties. It is revealed that O-termination tends to produce semiconducting o-MXenes, while the OH-termination effectively reduces the lattice thermal conductivity of o-MXenes. Dozens of o-MXenes are predicted to be potentially excellent thermoelectric materials for the first time and which are found to possess Seebeck coefficients higher than 100 μV/K and have ZT values larger than 0.5 at room temperature.