Atomistic Insights into the Influence of High Concentration H 2 O 2 /H 2 O on Al Nanoparticles Combustion: ReaxFF Molecules Dynamics Simulation.

The combination of Al nanoparticles (ANPs) as fuel and H 2 O 2 as oxidizer is a potential green space propellant. In this research, reactive force field molecular dynamics (ReaxFF-MD) simulations were used to study the influence of water addition on the combustion of Al/H 2 O 2 . The MD results showed that as the percentage of H 2 O increased from 0 to 30%, the number of Al-O bonds on the ANPs decreased, the number of Al-H bonds increased, and the adiabatic flame temperature of the system decreased from 4612 K to 4380 K. Since the Al-O bond is more stable, as the simulation proceeds, the number of Al-O bonds will be significantly higher than that of Al-H and Al-OH bonds, and the Al oxides (Al[O] x ) will be transformed from low to high coordination. Subsequently, the combustion mechanism of the Al/H 2 O 2 /H 2 O system was elaborated from an atomic perspective. Both H 2 O 2 and H 2 O were adsorbed and chemically activated on the surface of ANPs, resulting in molecular decomposition into free radicals, which were then captured by ANPs. H 2 molecules could be released from the ANPs, while O 2 could not be released through this pathway. Finally, it was found that the coverage of the oxide layer reduced the rate of H 2 O 2 consumption and H 2 production significantly, simultaneously preventing the deformation of the Al clusters' morphology.