Universality of electronic characteristics and photocatalyst applications in the two-dimensional Janus transition metal dichalcogenides

摘要

Due to mirror symmetry breaking, two-dimensional Janus transition metal dichalcogenides MXY (M = Mo, W; X, Y = S, Se, Te) present charming electronic properties. However, there have not been many related studies as of yet, and the intrinsic physical pictures are unclear. Here, we use first-principles calculations to explore the universality of electronic characteristics and photocatalyst applications of Janus MXY, finding that the induced dipole moment, vibrational frequency, Rashba parameters, and direct-indirect band transition of monolayer MXY are deeply associated with the atomic radius and electronegativity differences of chalcogen X and Y elements. The internal electric field renders Janus MXY the ideal photocatalysts. Moreover, the stacking-dependent on/off switch of the dipole moment further confirms that asymmetric Janus MXY serves as a promising candidate for highly efficient photocatalysts within a broad range from infrared, visible, to ultraviolet light.