C59N Heterofullerene: A Promising Catalyst for NO Conversion into N2O

We report, for the first time, the possibility of using N-doped C-60 fullerene (C59N) as a novel and highly active metal-free catalyst for reduction of NO molecules to N2O. First-principles density functional theory calculations are used to find the most energetically favorable adsorbed/coadsorbed configurations of NO molecules over C59N. Our results indicate that introducing a N impurity in C-60 can induce a positive charge and large spin density over the carbon atoms nearest to the dopant atom. Consequently, these carbon atoms are identified as the most reactive sites to interact with the NO molecule. According to our results, the dissociation of NO molecule over C59N is almost impossible, due to its relatively high activation energy (1.35eV). The reduction of NO over C59N starts with the coadsorption of two NO molecules to form (NO)(2) species, followed by the dissociation of (NO)(2) into N2O and an active atomic oxygen (O-ads). The energy barrier to convert NO molecules into N2O ranges from 0.33 to 0.75eV, which indicates this process is likely to proceed at normal temperature. Besides, by overcoming a negligible energy barrier (0.18eV), the remaining O-ads moiety can be easily eliminated by a CO molecule. To further understand the role of nitrogen atoms in the NO reduction process, the catalytic performance of high percentage N-doped fullerene (C48N12) is also studied.