Thermochemistry modeling of hydrogen and water influence on C20 cage decay

Abstract

Nanoscale materials based on fullerenes have a high density of covalent carbon–carbon bonds storing a great amount of energy, thus providing a high heat release upon their spontaneous explosion, as it is shown in the detailed theoretical analysis /1/ of nitrofullerene C60(NO2)12 decomposition by using of nonequilibrium reactive molecular dynamics. The initiation temperature of this explosion was found to be ≈1000 K and full decomposition into 96 individual atoms was achieved at temperature ≈5000 K, yielding energy release of (3/2)kB(96×5000 K – 1×1000 K) ≈ 62 eV, where kB is the Boltzmann constant. We propose to consider a decomposition of hydrogenated C20 cage molecule as a more stable form of nanoscale explosive. The fullerene C20 can be effectively hydrogenated unlike the fullerene C60, which is typically hydrogenated to C60H36 molecule /2/. It is known that a metastable state of the C20 cage molecule is thermally stable due to the considerable potential barrier between this state and the equilibrium state of the C20 bowl /3/. We propose to use this relative stability of the metastable state of the C20 cage covered by 20 hydrogen atoms (i.e. each carbon atom is bonded with one hydrogen atom). A detailed description of formation and decay of the hydrogenated C20 molecule requires to take into account a great number of processes like vibrations of atomic systems, thermodynamic processes, kinetics of carbon nanostructure hydrogenation, nonequilibrium statistical processes, electromagnetic radiation effects etc. Here we limit ourselves to an elementary thermochemistry consideration.