Dissociation of O2 molecule on Fe/Nx clusters embedded in C60 fullerene, carbon nanotube and graphene

Abstract

The O2 dissociation and yielding two separated O atoms is an essential step for the oxygen reduction reaction. Dissociation of the strong bond in the O2 often involves large activation barriers on metal particles used as catalysts. Here, the O2 dissociation on the Fe/Nx clusters embedded in the fullerene C60, carbon nanotube, and graphene nanomaterials have been studied theoretically using density functional theory. The following outcomes can be derived from our calculations: (1) The Fe/Nx clusters embedded in the C60, carbon nanotube, and graphene enhance the reactivity of these nanomaterials, however, it is more effective in the case of Fe/Nx clusters embedded in the graphene. (2) Consistent with the prediction of the reactivity descriptors, the maximum catalytic activity toward the O2 dissociation is related to the Fe/N4 cluster embedded in graphene. (3) The adsorption energies of the O2 adsorbed on the Fe/Nx clusters embedded in the C60, carbon nanotube and graphene increase with the increase Fe transition metal positive charges. (4) Our study demonstrates that the Fe/N4 cluster embedded in graphene can act as driving force for the O2 dissociation. (5) The energy barrier of the O2 dissociation process shows that the O2 dissociation on the Fe/N4 cluster embedded in the graphene will be kinetically preferable. These predictions open the route for the experimental studies of catalysts that offer high activity for oxygen reduction reaction processes.