A self-assembly strategy is developed to construct porous N and B doped carbon materials (BCN-P) as efficient metal-free ORR catalysts for zinc-air battery, which employs the macrocyclic molecule cucurbit[7]uril (CB7) and 3D aromatic-like closo-[B₁₂H₁₂]²⁻ as nitrogen and boron sources. BCN-P exhibits better ORR catalytic activity than its single dopant counterpart, and even comparable to Pt/C in zinc-air battery performance.

Abstract

Carbon nanomaterials doped with N and B could activate nearby carbon atoms to promote charge polarization through the synergistic coupling effect between N and B atoms, thus facilitating adsorption of O₂ and weakening O−O bond to enhance oxygen reduction reaction. Herein, a simple and controllable self-assembly strategy is applied to synthesize porous B, N co-doped carbon-based catalysts (BCN-P), which employs the macrocyclic molecule cucurbit[7]uril (CB7) as nitrogen source, and 3D aromatic-like closo-[B₁₂H₁₂]²⁻ as boron source. In addition, polystyrene microspheres are added to help introduce porous structure to expose more active sites. Benefitting from porous structures and the synergistic coupling effect between N and B atoms, BCN-P has a high onset potential (E_onset=0.846 V) and half-wave potential (E_1/2=0.74 V) in alkaline media. The zinc-air battery assembled with BCN-P shows high operating voltage (1.42 V), peak power density (128.7 mW cm⁻²) and stable charge/discharge cycles, which is even comparable with Pt/C.