Engineering structural and electronic properties of MXene-type Mo and W silicides via oxygen functionalization and strain

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Exploring two-dimensional (2D) materials with particular properties is essential for the development of nanoscale electronics devices. Here, we predict a new class of 2D MXene-type silicides M 2 Si (M = Mo, W) based on first-principles calculations. The intrinsic Mo 2 Si and W 2 Si monolayers are nonmagnetic metals but the MXene-type lattice is dynamically unstable. Interestingly, surface oxygen functionalization not only stabilizes the Mo 2 Si and W 2 Si monolayers, but also induces a giant band gap of up to 199[Formula: see text]meV, due to the large spin-orbit coupling effect in the W-5d orbital. Furthermore, this gap is robust against moderate biaxial strain, which is beneficial to the practical applications utilizing this material.