NANOSCALE SnO2 WITH WELL-DEFINED FACETS IMPROVING COMBUSTION PERFORMANCE OF ENERGETIC MATERIALS

Abstract

Catalytic activity of SnO2 nanocrystals with different percentages of the exposed [221] facets for the thermal decomposition of Cyclotrimethylenetrinitramine (RDX) was investigated. An enhancement in the catalytic activity was observed for the SnO2 nanocrystals with a higher percentage of the exposed [221] facets, in which the activation energy (Ea) of RDX decomposition was lowered from 172.6 to 125.5 kJ/mol, for octahedral SnO2 with over 90% of the exposed [221] facets. Theoretically evidenced by density functional theory calculations, such highly exposed [221] facets can be favorable for the adsorption and diffusion of NO2, and also facilitate the formation of active oxygen which can lead to the oxidation reaction of HCHO more completely in the catalytic decomposition of RDX. The effect of octahedral SnO2 on the combustion of solid rocket propellant was also investigated, which increased the burning rate of propellant strands by 30%. More important, typical fast-burning propellants are unstable due to oversensitivity to pressure variations, but the octahedral SnO2 yielded propellants with high yet stable burning rates over a broad pressure range.