Study of the bifunctional catalytic activity on Sr and Mn co-doped PrFeO3-δ Zinc-Air batteries cathode

Reasonable design of perovskite oxides with outstanding and durable oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is of vital importance to enhancing the performance of zinc-air batteries. In this paper, PrFeO3-δ and a series of Sr and Mn co-doped Pr0.6Sr0.4Fe1-xMnxO3-δ (x = 0, 0.2 and 0.4) perovskite materials were successfully prepared via a citrate-nitrate combustion process and used in rechargeable zinc-air batteries as bifunctional catalysts. The rotating disk electrode technique demonstrated the bifunctional catalytic activity of several materials in an alkaline medium increase in the order of Pr0.6Sr0.4Fe0.8Mn0.2O3-δ (PSFM-82), Pr0.6Sr0.4Fe0.6Mn0.4O3-δ (PSFM-64), Pr0.6Sr0.4FeO3-δ (PSFM-0) and PrFeO3-δ (PFO). Compare to PFO, PSFM-82 displayed a greater peak power density (56.3 mW·cm−2) as an oxygen electrode catalyst for zinc-air batteries. The smaller discharge-charge cycle difference (1.03 V) of PSFM-82 after 135 cycles (135 h) at the current density of 10 mA·cm−2 also demonstrates its notably bifunctional activity and excellent cycling stability than that of PFO. The enhanced electrocatalytic property of both ORR and OER could be owing to the greater specific surface area, higher electrical conductivity and the coexistence of Fe4+ and Mn3+ ions with optimal electron filling caused by the partial substitution of Pr with Sr and Fe with Mn.