Doped fullerene as a metal-free electrocatalyst for oxygen reduction reaction: A first-principles study

Abstract

The heteroatom-doped fullerene is systematically studied as an electrocatalyst for oxygen reduction reaction (ORR) on the cathode of fuel cells under the alkaline and acid conditions. Nitrogen-doped C60, i.e. C59N, can facilitate the ORR process and it is a promising candidate for efficient ORR electrocatalysts. The intrinsic C60 also possesses a high catalytic activity, which is different from graphene and is probably attributed to the curvature or pentagon defect of fullerene. We deduce that the curvature and pentagon defect are important factors to tune the catalytic ability. The fitted activity volcano diagram shows that the best achievable ORR activity of the heteroatom-doped fullerene, in the thermodynamic viewpoint, appears at ΔG*OH = 0.25 eV, which could be realized by dual or three-element-doping of C60 cage. The estimated standard equilibrium potential values are −0.52 and 0.25 V in alkaline and acid medium, respectively. Since the catalytic activity of the doped fullerenes depends on their IP and Egap, here we provide a simple and easy method, by measuring the IP and Egap, to roughly evaluate the catalytic ability of designed catalysts. This is vital to guide the design of new ORR catalysts with high catalytic activity and durability.