Metal Nanoparticles for Modifying Graphene Aerogels: A Molecular Dynamics Study

Honeycomb graphene aerogels offer a combination of graphene wall qualities, such as mechanical strength and binding, and the unique, engineered architecture of honeycombs. The honeycomb structure opens new opportunities for property modification, such as reinforcement with metal nanoparticles, which can increase strength and electrochemical performance. This study uses molecular dynamics simulations to examine the reinforcement of graphene honeycomb aerogels containing 2.7% and 5.8% randomly distributed Ni or Al nanoparticles. Metal nanoparticles considerably increase the resistance to compression: stress increase occurred for aerogels with Al nanoparticles at a density of 1.3 g/cm3, while for aerogels and filled with Ni, stress increase occurred at 2.0 g/cm3. The strengthening mechanism is volume repulsion when Al NPs repel the graphene cell walls, while Ni nanoparticles easily spread along the cell walls and provide less compression resistance, analogous to pure graphene aerogels. The tensile properties remained unaffected by the presence of either nanoparticle type since the same deformation mechanism (cell collapse) occurred for all aerogels. The maximal ultimate tensile strength achieved was 160 GPa. Temperatures ranging from 300 to 3000 K slightly affected the strength of all aerogels.