title: Ternary Spinel MCo2O4 (M = Mn, Fe, Ni, and Zn) Porous Nanorods as Bifunctional Cathode Materials for Lithium-O2 Batteries.
abstract: The development of Li-O2 battery electrocatalysts has been extensively explored recently. The Co3O4 oxide has attracted much attention because of its bifunctional activity and high abundance. In the present study, toxic Co(2+) has been replaced through the substitution on the tetrahedral spinel A site ions with environmental friendly metals (Mn(2+), Fe(2+), Ni(2+), and Zn(2+)), and porous nanorod structure are formed. Among these spinel MCo2O4 cathodes, the FeCo2O4 surface has the highest Co(3+) ratio. Thus, oxygen can be easily adsorbed onto the active sites. In addition, Fe(2+) in the tetrahedral site can easily release electrons to reduce oxygen and oxidize to half electron filled Fe(3+). The FeCo2O4 cathode exhibits the highest discharging plateau and lowest charging plateau as shown by the charge-discharge profile. Moreover, the porous FeCo2O4 nanorods can also facilitate achieving high capacity and good cycling performance, which are beneficial for O2 diffusion channels and Li2O2 formation/decomposition pathways.
authors.affiliation: †Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.|‡Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan University.
authors.forename: Saad Gomaa
authors.initials: SG
authors.lastname: Mohamed
authors.affiliation: †Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Yuan-Quei
authors.initials: YQ
authors.lastname: Tsai
authors.affiliation: †Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Chih-Jung
authors.initials: CJ
authors.lastname: Chen
authors.affiliation: †Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Tsai
authors.forename: Tai-Feng
authors.initials: TF
authors.lastname: Hung
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Chang
authors.affiliation: †Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.|∥Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 106, Taiwan.
authors.forename: Ru-Shi
authors.initials: RS
authors.lastname: Liu
keywords: MCo2O4; cathode materials; lithium−O2 batteries; porous nanorods; ternary metal oxides