A theoretical study of the thermoelectric properties of two-dimensional surface-functionalized MXene materials...

MXenes are a novel family of two-dimensional layered materials consisting of transition metal carbides, nitrides, or carbon-nitrides, and great interest has been shown in these materials because of their distinctive structural configurations. In this study, the electronic structures of functionalized ScYC(OH)H, ScYC(OH)F, and ScYCHF were initially evaluated through density-functional theory (DFT) to judge their stability in the two-dimensional state. Subsequently, based on the Boltzmann transport theory, we conducted an in-depth analysis of the key thermoelectric parameters of these materials, including the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF) and thermal conductivity (κ), with lattice thermal conductivity calculations accelerated using machine learning (MTP) methods. The results show that the n-type ScYCTT' (T = OH, H; T' = H, F) exhibits superior power factor performance compared to its p-type counterpart. Within the thermal range of 300 to 900 K, the thermoelectric figure of merit of the three materials (ZT) increases with increasing temperature, particularly under 900 K conditions, where the n-type ScYCTT' manifests remarkable ZT peaks of 0.97, 1.11, and 0.59, respectively, better than those of the p-type. Therefore, ScYCTT' exhibits promising thermoelectric performance across the 300-900 K temperature interval.