Multilayer graphene crystals with enhanced performances in oxygen reduction and zinc-air batteries interlayer carbon promoted O[double bond, length as m-dash]O bond dissociation.

O[double bond, length as m-dash]O bond activation determines activities of oxygen reduction reaction (ORR) catalysts, and developing metal-free catalysts that outperform precious metals remains challenging. Herein, we demonstrate the mechanochemical polymerization of pyrrole tandem carbonization for designing nitrogen-containing, micropore-penetrated multilayer graphene crystals (NM-MGCs) with abundant barrier-free nanochannels for O, leading to high exposure of carbon atoms adjacent to graphitic nitrogen. Due to the ordered multilayer structure with steady layer-by-layer van der Waals interaction, the resultant exposed interlayer carbon atoms exhibit much improved ability to activate O through adsorption-configuration-induced O[double bond, length as m-dash]O bond dissociation in the ORR with approximately zero energy barrier. Thus, the NM-MGCs show record-breaking ORR performance among metal-free catalysts, which can be fabricated as air cathodes for both flow and flexible Zn-air batteries, exhibiting high maximum power density, high specific capacity (815.30 mA h g at 5 mA cm), and extraordinary long-term cycling durability (>800 h) and round-trip energy efficiency (63.7%). The overall performance of Zn-air batteries assembled using the NM-MGCs surpass those of commercial Pt/C (20 wt%) and many literature-reported metal and/or metal-free electrocatalysts.