Ozone reaction with carbon nanostructures 1: Reaction between solid C-60 and C-70 fullerenes and ozone

摘要

The exposure of powdered crystals of C-60 and C-70 fullerenes to ozone with an O-3/O-2 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 C-60 and C-70 powders that were exposed to ozone show absorption bands indicating that oxidation was accompanied by formation of a,g-unsaturated carboxylic groups, aldehyde and other ketonic moieties. The spontaneous decay of O-3 in the O-3/O-2 atmosphere monitored by FT-IR spectroscopy was found to follow a pseudofirst order kinetic law with k(0) = 6.9 x 10(-5) s(-1). When powdered C-60 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 C-70. The accelerated disappearance of O-3 is due to its adsorption/reaction with the powdered fullerenes. After about similar to 1000 s the reaction enters in a second step wherein the disappearance of O-3 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.