Graphitic coated Al nanoparticles manufactured as superior energetic materials via laser ablation synthesis in organic solvents

The large heat release predicted in the early investigations of energetic aluminum nanoparticles (Al NPs) used in solid-state propulsion and pyrotechnics has been offset by hindered diffusion-limited detonation rates due to excess oxide shell formations and surface area loss from aggregations. We address these challenges by manufacturing graphitic shell coated Al NPs (< 20 nm sizes) via laser ablation synthesis in solution (LASiS) to preserve high surface areas and interfacial properties of Al NPs. Specifically, we use a high-energy laser to ablate Al pellets confined in either acetone or toluene to coat the laser-ablated Al NPs with graphitic shells generated from the thermal pyrolysis of the organic solvents. Energetic activities of the C/Al NPs were tested via the laser-induced air shock from energetic materials (LASEM) technique. We demonstrate that synthesis parameters such as organic solvents, laser flux and ablation times can be tuned to provide superior control of NP sizes/ag-gregation with the aid of the C shell formations and, in turn, their energetic behavior. This study unveils the synthesis-structure-property relations in LASiS-based manufacturing of energetic nanocapsules within graphitic shells that are safe to handle and can undergo kinetically controlled spontaneous energy release under desired conditions.