Probing the Catalytic Activity and Poisoning-Tolerance Ability of Endohedral Metallofullerene Fen@C60 (n = 1−7) Catalysts in the Oxygen Reduction Reaction

Abstract

In this paper, the oxygen reduction reaction catalytic activity and poisoning-tolerance ability of endohedral metallofullerene Fen@C60 (n = 1−7) catalysts are investigated by using DFT calculations. The calculation predicts very low catalytic activity of the pristine C60 fullerene, but significant activity enhancement is obtained when encapsulating iron clusters into C60 cage due to improved energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. With the increase of the size of encapsulated Fen cluster, the adsorption energies of all the oxygen reduction intermediates, such as OOH, O, and OH, become jointly stronger. Among all the screened Fen@C60 (n = 1−7) catalysts, Fe3@C60 possesses the highest oxygen reduction activity, with a predicted limiting potential of about 0.73 V that is comparable to that of Pt(111) surface (0.78 V). The limiting potentials for Fe2@C60, Fe4@C60 and Fe5@C60 are also relatively high, with the values of 0.64, 0.69, and 0.64 V, respectively. In addition, the above screened Fen@C60 catalysts also exhibit excellent poisoning-tolerance ability to SO2, H2S, CO, NO, and NH3 species, which is originated from the unstable physisorption interaction between these species and the catalysts that is completely different from the case of the easily poisoned Pt catalyst.