Oxygen Evolution at Manganite Perovskite Ruddlesden-Popper Type Particles: Trends of Activity on Structure, Valence and Covalence
| Autor: | Julius Scholz, Norbert Osterthun, Marcel Risch, Christian Jooss, Majid Ebrahimizadeh Abrishami, Vladimir Roddatis |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Inorganic chemistry
chemistry.chemical_element oxygen evolution reaction manganite perovskite Ruddlesden-Popper systems electrocatalyst X-ray absorption spectroscopy 02 engineering and technology Crystal structure 010402 general chemistry lcsh:Technology 01 natural sciences Oxygen Article General Materials Science lcsh:Microscopy lcsh:QC120-168.85 Valence (chemistry) lcsh:QH201-278.5 lcsh:T Rietveld refinement Oxygen evolution 021001 nanoscience & nanotechnology Manganite 0104 chemical sciences chemistry lcsh:TA1-2040 Covalent bond Chemical physics lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering lcsh:Engineering (General). Civil engineering (General) 0210 nano-technology lcsh:TK1-9971 Powder diffraction |
| Zdroj: | Materials Materials, Vol 9, Iss 11, p 921 (2016) Materials; Volume 9; Issue 11; Pages: 921 |
| ISSN: | 1996-1944 |
| Popis: | 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 Ca1xPrxMnO3 and the first-order RP-system Ca2xPrxMnO4 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. peerReviewed |
| Databáze: | OpenAIRE |
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