Ozone Reaction with Carbon Nanostructures 1: Reaction Between Solid C60 and C70 Fullerenes and Ozone

The exposure of powdered crystals of C60 and C70 fullerenes to ozone with an O3/O2 ratio of 9.7% w/w causes their immediate oxidation. The FT-IR spectroscopy shows the formation of CO2 and the accelerated disappearance of ozone. The infrared spectra of crystalline C60 and C70 powders that were exposed to ozone show absorption bands indicating that oxidation was accompanied by formation of alpha,beta-unsaturated carboxylic groups, aldehyde and other ketonic moieties. The spontaneous decay of O3 in the O3/O2 atmosphere monitored by FT-IR spectroscopy was found to follow a pseudofirst order kinetic law with k0 = 6.9 x 10(-5) s(-1). When powdered C60 is present in the system a k(C60)(1) = 2.0 x 10(-4) s(-1); k(C70)(1) = 1.4 x 10(-4) s(-1) for C70. The accelerated disappearance of O3 is due to its adsorption/reaction with the powdered fullerenes. After about approximately 1000 s the reaction enters in a second step wherein the disappearance of O3 slows down significantly due to the lack of further reaction sites on the powdered fullerene surfaces and due to accumulated CO2 in the gas phase which exerts an inhibitory effect in the ozone spontaneous decomposition.