On the mechanical response of graphene-capped copper nanoparticles

In this study, we investigated the mechanical behavior of pristine copper (Cu) nanoparticles (NPs) and Cu@graphene (Cu@G) hybrid NPs using molecular dynamics simulations. The longitudinal engineering strain was calculated as a measure of compression until reaching 25% of the initial size of the NPs. The stress-strain curves revealed the elastic-to-plastic transition in the Cu NPs at a longitudinal strain of 3.57% with a yield strength of 6.15 GPa. On the other hand, the Cu@G NPs exhibited a maximum average load point at a longitudinal strain of 6.81% with a yield strength of 8.26 GPa. The hybrid Cu@G NPs showed increased strength and resistance to plastic deformation compared to the pure Cu NPs, while the calculation of the elastic modulus indicated a higher load resistance provided by the graphene coverage for the Cu@G NPs. Furthermore, the analysis of atomic configurations, dislocations, and stress distribution demonstrated that the graphene flakes play a crucial role in preventing dislocation events and faceting in the Cu@G NPs by acting as a shock absorber, distributing the applied force on themselves, and producing a more homogeneous stress distribution on the Cu NPs; additionally, they prevent the movement of Cu atoms, reducing the occurrence of dislocations and surface faceting, thanks to their supportive effect. Overall, our findings highlight the potential of hybrid nanomaterials, such as Cu@G, for enhancing the mechanical properties of metallic NPs, which could have significant implications for the development of advanced nanomaterials with improved performance in a variety of applications.