title: Co@Co3O4 Encapsulated in Carbon Nanotube-Grafted Nitrogen-Doped Carbon Polyhedra as an Advanced Bifunctional Oxygen Electrode.
abstract: Efficient reversible oxygen electrodes for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are vitally important for various energy conversion devices, such as regenerative fuel cells and metal-air batteries. However, realization of such electrodes is impeded by insufficient activity and instability of electrocatalysts for both water splitting and oxygen reduction. We report highly active bifunctional electrocatalysts for oxygen electrodes comprising core-shell Co@Co3O4 nanoparticles embedded in CNT-grafted N-doped carbon-polyhedra obtained by the pyrolysis of cobalt metal-organic framework (ZIF-67) in a reductive H2 atmosphere and subsequent controlled oxidative calcination. The catalysts afford 0.85 V reversible overvoltage in 0.1 m KOH, surpassing Pt/C, IrO2 , and RuO2 and thus ranking them among one of the best non-precious-metal electrocatalysts for reversible oxygen electrodes.
authors.affiliation: Laboratory of Industrial Chemistry, Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Arshad
authors.initials: A
authors.lastname: Aijaz
authors.affiliation: Analytical Chemistry-Center for Electrochemical Sciences (CES), Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Justus
authors.initials: J
authors.lastname: Masa
authors.affiliation: Inorganic Chemistry II-Organometallics & Materials, Department of Chemistry and Biochemistry, Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Rösler
authors.affiliation: Laboratory of Industrial Chemistry, Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Wei
authors.initials: W
authors.lastname: Xia
authors.affiliation: Laboratory of Industrial Chemistry, Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Weide
authors.affiliation: Analytical Chemistry-Center for Electrochemical Sciences (CES), Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Alexander J R
authors.initials: AJ
authors.lastname: Botz
authors.affiliation: Inorganic Chemistry II-Organometallics & Materials, Department of Chemistry and Biochemistry, Ruhr-University Bochum, 44780, Bochum, Germany. roland.fischer@rub.de.
authors.forename: Roland A
authors.initials: RA
authors.lastname: Fischer
authors.affiliation: Analytical Chemistry-Center for Electrochemical Sciences (CES), Ruhr-University Bochum, 44780, Bochum, Germany. wolfgang.schuhmann@rub.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schuhmann
authors.affiliation: Laboratory of Industrial Chemistry, Ruhr-University Bochum, 44780, Bochum, Germany. muhler@techem.rub.de.|Max Planck Institute for Chemical Energy Conversion, 45470, Mülheim an der Ruhr, Germany. muhler@techem.rub.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Muhler
keywords: heterogeneous catalysts; metal nanoparticles; nanostructured materials; oxygen reduction; water oxidation