Abstract
Recently, 2D Mo2C, a new member of the MXene family, has attracted much attention due to the exotic superconducting properties discovered in 2D alpha-Mo2C. Here, not only 2D alpha-Mo2C but also 2D beta-Mo2C crystal sheets with distinct disordered carbon distributions were successfully grown. 2D beta-Mo2C shows a much stronger superconductivity than 2D alpha-Mo2C, and their superconductivities have different hydrostatic pressure responses. The superconducting transition temperatureT(c)of 2D alpha-Mo2C shows a dome-shaped profile under pressure, implying the existence of two competing effects arising from phononic and electronic properties, while for 2D beta-Mo2C,T(c)decreases monotonically with increasing pressure, possibly due to phonon stiffening. These results indicate that the electronic properties have a more important influence on the superconductivity in 2D alpha-Mo2C compared to 2D beta-Mo2C. The ordered and disordered carbon distributions in 2D alpha-Mo2C and beta-Mo2C, respectively, may be the underlying origin for their different electronic and superconducting properties.