Developing large-scale and highly efficient oxygen reduction reaction (ORR) catalysts acts a vital role in realizing wide application of metal-air batteries.Here,we propose a gas-foaming strategy to fabricate sustainable and 3D hierarchically porous N-doped carbon with high specific surface area and abundant defects sites derived from biomass.The obtained catalyst exhibits prominent ORR property with higher half-wave potential (0.861 V) and slightly lower kinetic current density (32.44mAcm 2),compared to Pt/C (0,856V and 43.61 mAcm-1).Furthermore,employing it as catalyst of air cathode,the Al-air battery delivers remarkable discharge performance with excellent power density of 401 mWcm-2,distinguished energy density of 2453,4Wh kg-1 and extremely high open-circuit voltage of 1.85V among the reported metal-air batteries in the literatures.This gas-foaming strategy for full utilization of biomass affords a chance to explore scalable advanced catalysts in metal-air battery.