Probing the activity of pure and N-doped fullerenes towards oxygen reduction reaction by density functional theory

Abstract

Fullerene can be potentially used as the electrocatalyst for oxygen reduction reaction (ORR) due to its curvature and pentagon defect. In this study, the ORR mechanisms and catalytic abilities of pure and N-doped fullerenes were investigated via DFT computations. Four different sized fullerenes, C20, C40, C60, and C180, with respectively the diameter of approximately 0.4, 0.6, 0.7, and 1.2 nm, were utilized to investigate the size effect on the ORR performance. The results reveal that the smallest (C20 and N-doped one) and the largest (C180 and C179N) fullerenes are not effective ORR catalysts candidates in view of their unsuitable adsorption strength to the ORR species. In contrast, N-doped C40 and C60, with the adsorption energy much close to those on Pt(111), manifest high ORR activity potentials. Further analysis of the relative energy diagram shows that the ORR process on C19N and C179N is completed through a H2OO dissociation mechanism, while on C39N and C59N it will undergo an OOH dissociation pathway. In addition, the C39N has the largest decreased energy of rate-determining step in the relative energy profile, suggesting its ORR activity is the best among all the different sizes of fullerenes that we studied.