Multilevel Theoretical Screening of Novel Two-Dimensional MA2Z4 Family for Hydrogen Evolution.

Abstract

The synthesis of 2D MoSi2N4 marked the birth of a new family of 2D MA2Z4 materials, whose potential applications are expected to sweep the field of nanoscale devices and catalysis in the future. In this work, we propose a multilevel screening workflow to systematically explore the mechanic stabilities, electronic properties, and hydrogen evolution performances of the 2D MA2Z4 family, among which seven stable, metallic, and highly active 2D MA2Z4 monolayers (2H-α-VGe2N4, 2H-α-NbGe2N4, 2H-α-TaGe2N4, 2H-α-NbSi2N4, 2H-β-VGe2N4, 2H-β-NbGe2N4, and 2H-β-TiGe2P4) are predicted as promising hydrogen evolution reaction (HER) catalysts with near-zero hydrogen adsorption free energy (ΔGH). The lowest unoccupied state energy (ELUS) of the MA2Z4 basal plane is identified as a concise descriptor to influence the electron filling and eventually determine its ΔGH. The criteria of -6.0 < ELUS < -5.6 eV is confirmed as the HER active window to explore novel HER catalysts. In particular, group-VI-terminated MA2Z4 basal planes have a higher ELUS (> -5.6 eV), which leads to weak H adsorption and poor HER activities accordingly.