Cobalt/Cobalt Oxide Surface for Water Oxidation

Hadi Feizi, Robabeh Bagheri, Zhenlun Song, Jian-Ren Shen, Suleyman Allakhverdiev, Mohammad Mahdi Najafpour

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Water splitting to produce molecular hydrogen is an essential method to store sustainable energies. One of the bottlenecks for water splitting is the availability of an efficient and stable water-oxidizing catalyst. Herein, metallic cobalt foil, after the treatment under high potential (10-60.0 V), was used for water oxidation. The cobalt/cobalt oxide surface was characterized by various spectroscopic, microscopy, X-ray diffraction, and electrochemical methods. Diffuse reflectance infrared Fourier transform spectroscopy showed peaks for Co oxide at 489 and 595 cm -1 attributed to the stretching of Co-O and bending of O-Co-O bonds in the CoO 6 octahedra. Small aggregated particles (ca. 50-100 nm) with a spherical morphology were detected by scanning electron microscopy, and high-resolution transmission electron microscopy from the mechanically separated particles indicated spacings of 2.5-2.6 Å corresponding to the interplanar spacings of the (011) plane for Co 3 O 4 . Selected area (electron) diffraction showed concentric rings centered on a bright central spot, indicating a polycrystalline material. Each ring is related to planes of different orientation and different interplanar spacing, attributed to metallic cobalt and cobalt oxides. X-ray diffraction resulted in patterns corresponding to Co 3 O 4 and CoO(OH), and X-ray photoelectron spectroscopy could confirm the formation of metallic cobalt, Co(II) and Co(III) oxides on the surface of the electrode. These results suggest that the oxide on the surface of foil could be a mixture of different phases of Co oxide containing Co 3 O 4 and CoO(OH). Under overpotentials of 460 and 780 mV, current densities of 0.144 and 0.5 A/cm 2 were observed at pH-14 without dropping of IR. To the best of our knowledge, the three-dimensional electrode obtained here is among the most efficient cobalt-based water-oxidizing electrodes under alkaline conditions reported so far and may be applied in large scale water-splitting systems.

Original languageEnglish
Pages (from-to)6093-6105
Number of pages13
JournalACS Sustainable Chemistry and Engineering
Volume7
Issue number6
DOIs
Publication statusPublished - Mar 18 2019

Fingerprint

Cobalt
cobalt
oxide
oxidation
Oxidation
Oxides
Water
electrode
spacing
water
Metal foil
Electrodes
X ray diffraction
X-ray diffraction
Polycrystalline materials
electrochemical method
High resolution transmission electron microscopy
Electron diffraction
Stretching
cobalt oxide

Keywords

  • Artificial photosynthesis
  • Cobalt
  • Energy
  • Oxygen
  • Water oxidation

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment

Cite this

Cobalt/Cobalt Oxide Surface for Water Oxidation. / Feizi, Hadi; Bagheri, Robabeh; Song, Zhenlun; Shen, Jian-Ren; Allakhverdiev, Suleyman; Najafpour, Mohammad Mahdi.

In: ACS Sustainable Chemistry and Engineering, Vol. 7, No. 6, 18.03.2019, p. 6093-6105.

Research output: Contribution to journalArticle

Feizi, Hadi ; Bagheri, Robabeh ; Song, Zhenlun ; Shen, Jian-Ren ; Allakhverdiev, Suleyman ; Najafpour, Mohammad Mahdi. / Cobalt/Cobalt Oxide Surface for Water Oxidation. In: ACS Sustainable Chemistry and Engineering. 2019 ; Vol. 7, No. 6. pp. 6093-6105.
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AB - Water splitting to produce molecular hydrogen is an essential method to store sustainable energies. One of the bottlenecks for water splitting is the availability of an efficient and stable water-oxidizing catalyst. Herein, metallic cobalt foil, after the treatment under high potential (10-60.0 V), was used for water oxidation. The cobalt/cobalt oxide surface was characterized by various spectroscopic, microscopy, X-ray diffraction, and electrochemical methods. Diffuse reflectance infrared Fourier transform spectroscopy showed peaks for Co oxide at 489 and 595 cm -1 attributed to the stretching of Co-O and bending of O-Co-O bonds in the CoO 6 octahedra. Small aggregated particles (ca. 50-100 nm) with a spherical morphology were detected by scanning electron microscopy, and high-resolution transmission electron microscopy from the mechanically separated particles indicated spacings of 2.5-2.6 Å corresponding to the interplanar spacings of the (011) plane for Co 3 O 4 . Selected area (electron) diffraction showed concentric rings centered on a bright central spot, indicating a polycrystalline material. Each ring is related to planes of different orientation and different interplanar spacing, attributed to metallic cobalt and cobalt oxides. X-ray diffraction resulted in patterns corresponding to Co 3 O 4 and CoO(OH), and X-ray photoelectron spectroscopy could confirm the formation of metallic cobalt, Co(II) and Co(III) oxides on the surface of the electrode. These results suggest that the oxide on the surface of foil could be a mixture of different phases of Co oxide containing Co 3 O 4 and CoO(OH). Under overpotentials of 460 and 780 mV, current densities of 0.144 and 0.5 A/cm 2 were observed at pH-14 without dropping of IR. To the best of our knowledge, the three-dimensional electrode obtained here is among the most efficient cobalt-based water-oxidizing electrodes under alkaline conditions reported so far and may be applied in large scale water-splitting systems.

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