Cerium ion intercalated MnO2 nanospheres with high catalytic activity toward oxygen reduction reaction for aluminum-air batteries

Manganese oxide is one of the most extensively studied electrocatalysts for oxygen reduction reaction (ORR) due to its high abundance and environmental friendliness. In this work, cerium ion intercalated birnessite-type manganese oxide (δ-MnO2) dispersed on carbon (CeMnO2/C) with high-efficient oxygen reduction reaction(ORR) electrocatalytic ability in alkaline media is prepared via facile aqueous reactions for the first time. The as-prepared catalyst shows morphology like quasi special nanospheres intertwined by plenty of nanorods just like knitting wool balls. Compared with MnO2/C, the onset and half-wave potential of 4.8% CeMnO2/C shift positively 27 and 57 mV, respectively, and are close to those of Pt/C. The oxygen reduction reaction occurring on 4.8% CeMnO2/C undergoes a 4-electron transfer pathway with the HO2− yield lee than 2%, which is much lower than that produced on Pt/C. The CeMnO2/C catalyst also exhibits excellent long-term stability with current retention of 96.4% after aging for 40000 s. The aluminum-air battery applying 4.8% CeMnO2/C as cathode catalyst gives out the peak power density of 348.8 mW cm−2 in 4 M KOH aqueous solution. After more than 300-h discharging, the voltage degradation of 4.8% CeMnO2/C is only 2% per 100 h. In all, the excellent performance of the Ce-intercalated MnO2/C demonstrates its enormous potential as ORR catalyst in metal-air batteries.