title: Comprehensive Study of an Earth-Abundant Bifunctional 3D Electrode for Efficient Water Electrolysis in Alkaline Medium.
abstract: We report efficient electrolysis of both water-splitting half reactions in the same medium by a bifunctional 3D electrode comprising Co3O4 nanospheres nucleated on the surface of nitrogen-doped carbon nanotubes (NCNTs) that in turn are grown on conductive carbon paper (CP). The resulting electrode exhibits high stability and large electrochemical activity for both oxygen and hydrogen evolution reactions (OER and HER). We obtain a current density of 10 mA/cm(2) in 0.1 M KOH solution at overpotentials of only 0.47 and 0.38 V for OER and HER, respectively. Additionally, the experimental observations are understood and supported by analyzing the Co3O4:NCNT and NCNT:CP interfaces by ab initio calculations. Both the experimental and the theoretical studies indicate that firm and well-established interfaces along the electrode play a crucial role on the stability and electrochemical activity for both OER and HER.
authors.affiliation: Department of Physics, Umeå University , S-901 87 Umeå, Sweden.
authors.forename: Tiva
authors.initials: T
authors.lastname: Sharifi
authors.affiliation: Department of Physics, Umeå University , S-901 87 Umeå, Sweden.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Gracia-Espino
authors.affiliation: Department of Physics, Umeå University , S-901 87 Umeå, Sweden.
authors.forename: Xueen
authors.initials: X
authors.lastname: Jia
authors.affiliation: Department of Physics, Umeå University , S-901 87 Umeå, Sweden.
authors.forename: Robin
authors.initials: R
authors.lastname: Sandström
authors.affiliation: Department of Physics, Umeå University , S-901 87 Umeå, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wågberg
keywords: bifunctional catalyst; hydrogen evolution reaction; nitrogen-doped carbon nanotubes; oxygen evolution reaction; transition metal oxides; water splitting