Combined experimental and reactive molecular dynamics study on stability and oxidation of aluminum nanoparticles with silane-based coatings

The introduction of high-energy aluminum nanoparticles (ANPs) into hydrocarbon-based liquid fuels enhances energy density and combustion efficiency. However, their strong tendency to aggregate and oxidize at storage temperatures poses significant challenges, affecting dispersion stability and fuel performance. This study investigates the effectiveness of silane coatings in mitigating these challenges through a combination of experimental synthesis and reactive molecular dynamics (MD) simulations. Experimentally, FT-IR analysis and sedimentation tests confirm the successful adsorption of octadecyltriethoxysilane (OTES), triethoxy(octyl)silane (TEOS), (3-aminopropyl)triethoxysilane (APTS), and tris(trimethylsilyloxy)silane (TMSS) onto ANPs, with OTES exhibiting the highest dispersion stability in hydrocarbon fuels. MD simulations further reveal atomic-level reaction steps in the surface coating, highlighting that OTES undergoes C–O bond dissociation, forming Al–O–Si linkages that strengthen its adhesion to ANPs. RDF analysis demonstrates a progressive increase in surface coverage across multiple coating cycles, leading to a stable hydrophobic layer that effectively prevents water-induced hydrolysis and oxidation. Additional MD analyses confirm that OTES-ANPs suppress aggregation and sintering at elevated temperatures (2000 K), while improving oxidation efficiency by enabling the self-detachment of the coating. These findings establish silane coatings, particularly OTES, as a promising strategy for stabilizing metal nanoparticles in high-energy-density fuel applications, mitigating oxidation, and optimizing combustion performance.