Bimetallic alloys encapsulated in fullerenes as efficient oxygen reduction or oxygen evolution reaction catalysts: A density functional theory study.

• The ORR and OER on bimetallic alloys encapsulated in fullerenes are studied by DFT. • C 50 and C 60 are the better carbon shell to encapsulate bimetallic alloys than C 40. • Co 1 Ni 3 @C 50 possesses the best ORR activity with the overpotential of 0.35 V. • Co 2 Ni 2 @C 60 has the most excellent OER activity with the overpotential of 0.36 V. [Display omitted] Revealing the structure-activity relationship of catalysts is conducive to design high-activity catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this paper, the ORR and OER catalytic activity of bimetallic alloys encapsulated in fullerenes M1 x M2 4− x @C n (M1 x M2 4− x represents Fe x Co 4− x , Fe x Ni 4− x , Co x Ni 4− x ; x = 1, 2, 3; n = 40, 50, 60) are investigated by density functional theory methods. The calculated encapsulation energy (E enc) indicates that except for the value on Fe 1 Ni 3 @C 60 , all the E enc values are positive on the studied M1 x M2 4− x @C n , suggesting that additional externally supplied energy will be needed to encapsulate bimetallic alloys in fullerenes. As the size of the C n cage decreases, the charge transfer between the alloy core and the carbon shell becomes greater, resulting in a roughly increase in the binding strength of the reaction intermediates on M1 x M2 4− x @C n. Compared with C 40 , C 50 and C 60 fullerenes are recognized as the more suitable shell for encapsulating bimetallic alloys toward ORR and OER. Based on the current study, Co 1 Ni 3 @C 50 is screened out with the best ORR activity (η ORR = 0.35 V) and Co 2 Ni 2 @C 60 shows the most excellent OER activity (η OER = 0.36 V) among all the M1 x M2 4− x @C n. [ABSTRACT FROM AUTHOR]