▎ 摘　　要

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 nano-sheet/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 O-2* 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).