Next Article in Journal
Preparation of Cement Composites with Ordered Microstructures via Doping with Graphene Oxide Nanosheets and an Investigation of Their Strength and Durability
Next Article in Special Issue
Controlling Oxygen Mobility in Ruddlesden–Popper Oxides
Previous Article in Journal
(Bi,Sr) (Fe1−x,Mx)O3−δ (M = Co, Ni and Mn) Cathode Materials with Mixed Electro-Ionic Conductivity
Open AccessArticle

Oxygen Evolution at Manganite Perovskite Ruddlesden-Popper Type Particles: Trends of Activity on Structure, Valence and Covalence

Institute of Materials Physics, University of Goettingen, Friedrich-Hund-Platz 1, Goettingen 37077, Germany
*
Author to whom correspondence should be addressed.
Academic Editor: Sofoklis Makridis
Materials 2016, 9(11), 921; https://doi.org/10.3390/ma9110921
Received: 7 October 2016 / Revised: 3 November 2016 / Accepted: 4 November 2016 / Published: 14 November 2016
(This article belongs to the Special Issue (Photo)Electrochemistry of Perovskites)
An improved understanding of the correlation between the electronic properties of Mn-O bonds, activity and stability of electro-catalysts for the oxygen evolution reaction (OER) is of great importance for an improved catalyst design. Here, an in-depth study of the relation between lattice structure, electronic properties and catalyst performance of the perovskite Ca1−xPrxMnO3 and the first-order RP-system Ca2−xPrxMnO4 at doping levels of x = 0, 0.25 and 0.5 is presented. Lattice structure is determined by X-ray powder diffraction and Rietveld refinement. X-ray absorption spectroscopy of Mn-L and O-K edges gives access to Mn valence and covalency of the Mn-O bond. Oxygen evolution activity and stability is measured by rotating ring disc electrode studies. We demonstrate that the highest activity and stability coincidences for systems with a Mn-valence state of +3.7, though also requiring that the covalency of the Mn-O bond has a relative minimum. This observation points to an oxygen evolution mechanism with high redox activity of Mn. Covalency should be large enough for facile electron transfer from adsorbed oxygen species to the MnO6 network; however, it should not be hampered by oxidation of the lattice oxygen, which might cause a crossover to material degradation. Since valence and covalency changes are not entirely independent, the introduction of the energy position of the eg pre-edge peak in the O-K spectra as a new descriptor for oxygen evolution is suggested, leading to a volcano-like representation of the OER activity. View Full-Text
Keywords: oxygen evolution reaction; manganite perovskite; Ruddlesden-Popper systems; electrocatalyst; X-ray absorption spectroscopy oxygen evolution reaction; manganite perovskite; Ruddlesden-Popper systems; electrocatalyst; X-ray absorption spectroscopy
Show Figures

Figure 1

MDPI and ACS Style

Ebrahimizadeh Abrishami, M.; Risch, M.; Scholz, J.; Roddatis, V.; Osterthun, N.; Jooss, C. Oxygen Evolution at Manganite Perovskite Ruddlesden-Popper Type Particles: Trends of Activity on Structure, Valence and Covalence. Materials 2016, 9, 921.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop