A Novel Two-Dimensional ZnSiP(2) Monolayer as an Anode Material for K-Ion Batteries and NO(2) Gas Sensing

Using the crystal-structure search technique and first-principles calculation, we report a new two-dimensional semiconductor, ZnSiP(2), which was found to be stable by phonon, molecular-dynamic, and elastic-moduli simulations. ZnSiP(2) has an indirect band gap of 1.79 eV and exhibits an anisotropic character mechanically. Here, we investigated the ZnSiP(2) monolayer as an anode material for K-ion batteries and gas sensing for the adsorption of CO, CO(2), SO(2), NO, NO(2), and NH(3) gas molecules. Our calculations show that the ZnSiP(2) monolayer possesses a theoretical capacity of 517 mAh/g for K ions and an ultralow diffusion barrier of 0.12 eV. Importantly, the ZnSiP(2) monolayer exhibits metallic behavior after the adsorption of the K-atom layer, which provides better conductivity in a period of the battery cycle. In addition, the results show that the ZnSiP(2) monolayer is highly sensitive and selective to NO(2) gas molecules.