Molecular Dynamics Investigation of the Toughening Mechanism in Core–Shell Nanoporous Gold Modified by Pt Layers: Implications for Sensing Applications

Abstract

Nanoporous metals demonstrate significant potential in a variety of innovative structures and functional domains, but their limited macroscopic plasticity hinders their industrial application. In this work, we constructed a core–shell structure by modifying nanoporous gold (NP-Au) with Pt atoms and investigated its mechanical response via molecular dynamics simulations. The results showed that the introduction of the Pt shell layer to form a core–shell structure effectively enhances the plasticity of NP-Au. Specifically, the lattice mismatch between the Pt shell layer and Au core layer induces elevated interfacial stress, leading to heightened initial dislocation density and intensified dislocation activity during deformation, which promotes the formation of Lomer–Cottrell locks and helps resist fracture. Additionally, the Pt shell layer mitigates strain localization and facilitates the nucleation and propagation of nanotwins. These synergistic mechanisms collectively contribute to the observed enhancement in plasticity, with greater reinforcement observed as the thickness of the Pt coating layer increases. Through quantitative comparative analysis between decorated specimens with equivalent relative density to NP-Au, it can be concluded that the strength and modulus augmentation in coated NP-Au@Pt might primarily stem from an increase in relative density rather than the special core–shell structure. Our findings clarify the toughening mechanism of the core–shell nanoporous structure, which provides a structural design strategy of ductile nanoporous materials for sensing applications.