2D Transition-Metal Silicides as Analogs of MXenes: A First-Principles Exploration

The family of 2D transition metal carbides, carbonitrides, and nitrides (MXenes) has aroused scientific research due to their unique electrical, optical, and chemical properties and their versatile applications. Based on first-principles calculations, ten transition metal silicide (M2Si, M = Sc, Ti, V, Cr, Mn, Co, Zn, Y, Nb, and Mo) monolayers are studied. Three stable 2D M2Si (M = Mn, Co, and Y) crystals are identified through the investigation of thermodynamic, dynamical, and thermal perspectives. Among them, Y2Si monolayer is a nonmagnetic metal, whereas Mn2Si and Co2Si monolayers are antiferromagnetic metals. The three monolayers are chemically inert to H-2 and N-2, but highly active to O-2, and only Y2Si with its surface functionalized by oxygen exhibits good thermal stability, whose magnetic and electronic properties retain its pristine counterpart. In addition, it is found that the Y2Si shows good electrocatalytic performance in hydrogen evolution reaction (HER). These stable 2D M2Si monolayers have potential in the fields of electronics and electrocatalysis.