title: A Metal-Organic Framework Derived Porous Cobalt Manganese Oxide Bifunctional Electrocatalyst for Hybrid Na-Air/Seawater Batteries.
abstract: Spinel-structured transition metal oxides are promising non-precious-metal electrocatalysts for oxygen electrocatalysis in rechargeable metal-air batteries. We applied porous cobalt manganese oxide (CMO) nanocubes as the cathode electrocatalyst in rechargeable seawater batteries, which are a hybrid-type Na-air battery with an open-structured cathode and a seawater catholyte. The porous CMO nanocubes were synthesized by the pyrolysis of a Prussian blue analogue, Mn3[Co(CN)6]2·nH2O, during air-annealing, which generated numerous pores between the final spinel-type CMO nanoparticles. The porous CMO electrocatalyst improved the redox reactions, such as the oxygen evolution/reduction reactions, at the cathode in the seawater batteries. The battery that used CMO displayed a voltage gap of ∼0.53 V, relatively small compared to that of the batteries employing commercial Pt/C (∼0.64 V) and Ir/C (∼0.73 V) nanoparticles and without any catalyst (∼1.05 V) at the initial cycle. This improved performance was due to the large surface area (catalytically active sites) and the high oxidation states of the randomly distributed Co and Mn cations in the CMO. Using a hard carbon anode, the Na-metal-free seawater battery exhibited a good cycle performance with an average discharge voltage of ∼2.7 V and a discharge capacity of ∼190 mAh g-1hard carbonduring 100 cycles (energy efficiencies of 74-79%).
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Mari
authors.initials: M
authors.lastname: Abirami
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Soo Min
authors.initials: SM
authors.lastname: Hwang
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Juchan
authors.initials: J
authors.lastname: Yang
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Sirugaloor Thangavel
authors.initials: ST
authors.lastname: Senthilkumar
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Junsoo
authors.initials: J
authors.lastname: Kim
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Woo-Seok
authors.initials: WS
authors.lastname: Go
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Baskar
authors.initials: B
authors.lastname: Senthilkumar
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Hyun-Kon
authors.initials: HK
authors.lastname: Song
authors.affiliation: School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 44919, Republic of Korea.|Energy Materials and Devices Lab, 4TOONE Corporation , UNIST-gil 50, Ulsan 44919, Republic of Korea.
authors.forename: Youngsik
authors.initials: Y
authors.lastname: Kim
keywords: Na−air; Prussian blue analogue; cobalt manganese oxide; electrocatalyst; metal organic framework; seawater battery