Electronic communication between transition metal nanoparticle and single atom: Endohedral metallofullerenes single-atom catalysts for oxygen reduction reaction catalysis

Civil-used proton exchange membrane fuel cell (PEMFC) may be the potential candidate for the construction of the global new energy system including the use of hydrogen energy. Nevertheless, the cathode oxygen reduction reaction (ORR) occurs sluggishly, reining the conversion efficiency of it, which hinders the further commercialization of PEMFC. Currently, the replacement of undesirable Pt catalysts by more stable and economical catalytic materials is the main topic in the field of ORR. Herein, ferromagnetic metal-based endohedral metallofullerenes (EMFs) electrocatalyst with single-atomic shell decoration (M4@MN4C60, M = Fe, Co, Ni) are theoretically constructed and evaluated by the density functional theory method. The encapsulation energy calculation reveals that the synthesis of all EMFs requires additional external energy supply, which can explain why few successfully experimental synesis of EMFs have been reported. Among all studied catalysts, the CoN4C60 stands out with the highest ORR performance comparable to Pt, and the Fe- and Ni- based EMFs shows considerable activity enhancement after the cluster encapsulation. The electronic structure calculation reveals that the encapsulated Fe4 cluster leads to an electron accumulation around the Fe atom in active center, thereby weakening the *OH binding and enhance the ORR performance.