Catalytic active interfacial B–C bonds of boron nanosheet/reduced graphene oxide heterostructures for efficient oxygen reduction reaction

Abstract

The boron doped carbon nanomaterials that include in-plane B–C bonds at the local structure are considered as an efficient electrocatalyst for oxygen reduction reaction (ORR). However, a fundamental understanding about the electrocatalytic activity of out-of-plane B–C bonds remains unclear. Herein, we synthesize a boron nanosheet/reduced graphene oxide (B@rGO) heterostructure, where out-of-plane B–C chemical bonds are formed at the heterointerfaces, greatly improving the ORR activity. As verified by the combined experimental analyses and theoretical calculations, the ORR activity is boosted because the out-of-plane B–C chemical bonds contribute to the cleavage of O–O bond of O2* intermediate. The B@rGO heterostructure composite exhibits much higher ORR activity than those of respective boron and rGO nanosheets as demonstrated by half-wave potential, Tafel slope, electron transfer number, and electrochemical active area, achieving better durability and methanol tolerance than the commercial 20 wt% Pt/C catalyst. In this context, primary Zn–air battery, using the as-synthesized B@rGO heterostructure composite as metal-free electrocatalyst, delivers high peak power density of 131 mW cm−2 and specific capacity of 639.3 mAh gZn−1.