title: Electronic Coupling of Cobalt Nanoparticles to Nitrogen-Doped Graphene for Oxygen Reduction and Evolution Reactions.
abstract: The rational design of nonprecious-metal electrocatalysts with activities comparable to or greater than that of platinum is extremely valuable to the development of high energy density metal-air batteries. Herein, the two-step preparation of a highly active oxygen electrocatalyst based on ultrasmall cobalt nanoparticles stabilized in a nitrogen-doped graphene matrix is reported. The catalyst performs as well as the commercial Pt/C catalyst in the oxygen reduction reaction, and better than the Pt/C catalyst in the oxygen evolution reaction. This particular electrocatalyst could significantly lower the overpotentials of oxygen electrochemical reactions in aqueous lithium-air batteries to attain a round-trip efficiency of about 79.0 % at a current density of 0.1 mA cm-2, thereby surpassing the performance of the commercial Pt/C catalyst. The good performance may be attributed to strong metal-support interactions, maximized by a high dispersion of ultrasmall cobalt nanocrystals in a nitrogen-doped graphene matrix, which yields electrocatalytic properties greater than the sum of its parts.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Dr. Singapore, 119260, Singapore.|Department of Mechanical Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore, 117581, Singapore.
authors.forename: Chaohe
authors.initials: C
authors.lastname: Xu
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Dr. Singapore, 119260, Singapore.
authors.forename: Meihua
authors.initials: M
authors.lastname: Lu
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore, 117581, Singapore.
authors.forename: Binggong
authors.initials: B
authors.lastname: Yan
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Dr. Singapore, 119260, Singapore.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhan
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore, 117581, Singapore.
authors.forename: Palani
authors.initials: P
authors.lastname: Balaya
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore, 117581, Singapore.
authors.forename: Li
authors.initials: L
authors.lastname: Lu
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Dr. Singapore, 119260, Singapore.
authors.forename: Jim Yang
authors.initials: JY
authors.lastname: Lee
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D011211:Electric Power Supplies; D055664:Electrochemical Techniques; D006108:Graphite / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009584:Nitrogen; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*
chemical_list: D003035:Cobalt; D006108:Graphite; D009584:Nitrogen; D010100:Oxygen
keywords: cobalt; electrochemistry; graphene; heterogeneous catalysis; nanoparticles