MXenes, the new 2D transition metal carbides and nitrides, have recently attracted
extensive attention due to their diverse applications and excellent performances.
However, the thermal and electrical properties of most MXene materials are yet to
be studied. In this work, we investigate the electrical and thermal properties of
semiconducting Sc2CT2 (T = F, OH) MXenes using first-principles calculations. Both
of the Sc2CT2 (T = F, OH) MXenes are determined to show excellent carrier mobilities.
The electron mobility in the Sc2CF2 MXene is found to be strongly anisotropic at room
temperature, with values of 5.03 × 10(3) and 1.07 × 10(3) cm(2) V(-1) s(-1) in the
zigzag and armchair directions, respectively. The predicted electron mobility in the
zigzag direction of the Sc2CF2 is nearly four-fold that in the armchair direction
of the promising semiconductor phosphorene. In contrast to Sc2CF2, Sc2C(OH)2 presents
approximately isotropic electron mobility. The values at room temperature in the zigzag
and armchair directions are calculated as 2.06 × 10(3) cm(2) V(-1) s(-1) and 2.19
× 10(3) cm(2) V(-1) s(-1), respectively. In regard to the thermal properties, the
thermal conductivities of the Sc2CT2 (T = F, OH) MXenes have been determined. The
predicted values are higher than those of most metals and semiconducting low-dimensional
materials, such as monolayer MoS2 and phosphorene. In particular, the room-temperature
thermal conductivity along the Sc2CF2 armchair direction has been determined to be
as high as 472 W m(-1) K(-1) based on a flake length of 5 μm, which is even higher
than that of the best traditional conductor silver. The corresponding value in the
zigzag direction of Sc2CF2 is calculated to be 178 W m(-1) K(-1). The thermal conductivity
in Sc2C(OH)2 is less anisotropic and lower compared to that in Sc2CF2. The room-temperature
value in the armchair (zigzag) direction is determined to be 173 W m(-1) K(-1) (107
W m(-1) K(-1)). Based on their excellent electron mobilities and high thermal conductivities,
both of the Sc2CT2 (T = F, OH) MXenes could be promising candidate materials for the
next generation of electronic devices.