title: Efficient and Durable Bifunctional Oxygen Catalysts Based on NiFeO@MnOxCore-Shell Structures for Rechargeable Zn-Air Batteries.
abstract: Rechargeable Zn-air battery is limited by the sluggish kinetics and poor durability of the oxygen catalysts. In this Research Article, a new bifunctional oxygen catalyst has been developed through embedding the ultrafine NiFeO nanoparticles (NPs) in a porous amorphous MnOxlayer, in which the NiFeO-core contributes to the high activity for the oxygen evolution reaction (OER) and the amorphous MnOx-shell functions as active phase for the oxygen reduction reaction (ORR), promoted by the synergistic effect between the NiFeO core and MnOxshell. The synergistic effect is related to the electron drawing of NiFeO core from MnOxshell, which decreases the affinity and adsorption energy of oxygen on MnOxshell and significantly increases the kinetics of ORR. The electrocatalytic activity and durability of NiFeO@MnOxdepends strongly on the NiFeO:MnOxratio. NiFeO@MnOxwith NiFeO:MnOxweight ratio of 1:0.8 shows the best performance for reversible ORR and OER, with a potential gap (ΔE) of 0.792 V to achieve a current density of 3 mA cm-2for ORR (EORR=3) and 5 mA cm-2for OER (EOER=5) in 0.1 M KOH solution. The high activity of the NiFeO@MnOx(1:0.8) has been demonstrated in a Zn-air battery. Zn-air battery fabricated using the NiFeO@MnOx(1:0.8) oxygen electrode shows similar initial performance with that of Pt-Ir/C oxygen electrode but a much better durability under charge and discharge cycles as the result of the structure confinement effect of amorphous MnOx. The results demonstrate NiFeO@MnOxas an effective bifunctional oxygen catalysts for rechargeable metal-air batteries.
authors.affiliation: Fuels and Energy Technology Institute & Department of Chemical Engineering, Curtin University , Perth, Western Australia 6102, Australia.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, Hunan, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Dou
authors.affiliation: John de Laeter Centre, Curtin University , Perth, Western Australia 6102, Australia.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Veder
authors.affiliation: State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, Hunan, China.
authors.forename: Shuangyin
authors.initials: S
authors.lastname: Wang
authors.affiliation: Centre for Microscopy, Characterization and Analysis (CMCA), The University of Western Australia , Clawley, Western Australia 6009, Australia.
authors.forename: Martin
authors.initials: M
authors.lastname: Saunders
authors.affiliation: Fuels and Energy Technology Institute & Department of Chemical Engineering, Curtin University , Perth, Western Australia 6102, Australia.
authors.forename: San Ping
authors.identifier: http://orcid.org/0000-0002-7042-2976
authors.initials: SP
authors.lastname: Jiang
keywords: NiFeO@MnOx core−shell catalysts; bifunctional oxygen catalysts; rechargeable Zn−air batteries; structure confinement; synergistic effect