Electronic structure, interfacial characteristics and sodium ion dynamics in GaN/SnS2@GDY heterostructures: a first-principles study

Abstract

In this study, we successfully constructed GaN/SnS₂@graphdiyne (GaN/SnS₂@GDY) heterostructures and used first-principles calculations to deeply investigate their electronic structure features and sodium ion storage kinetics. The thermodynamic structural stability was verified through ab initio molecular dynamics (AIMD) simulation calculations. Besides, calculations reveal that the Young’s modulus of the GaN/SnS₂@GDY heterostructure is 331 N/m, with a Poisson’s ratio of 0.38, significantly higher than that of the individual materials, which can effectively resist volume changes during charging and discharging cycles. Moreover, the coupling effects and charge transfer mechanisms at different interfaces were analyzed through the calculation system of differential charge density and work function. The DOS calculations results show that the GaN/SnS₂@GDY heterostructure exhibits a zero band-gap feature, resulting in excellent electrical conductivity. The migration energy of Na⁺ at the SnS₂/GDY interface is significantly reduced to 0.57 eV. In addition, the differential charge density results reveals that the electron transfer of Na⁺ at the GaN/SnS₂ and SnS₂/GDY heterointerfaces are 0.76 e and 0.91 e, respectively. Meanwhile, the binding energy calculations reveals that the binding energies of Na⁺ at the GaN/SnS₂ and SnS₂/GDY heterointerfaces are − 0.37 eV and − 3.17 eV, respectively. These results provide important information for studying the storage mechanisms of Na⁺ at different interfaces.