Shen, Zechao ; Qu, Mei ; Shi, Jueli ; Oropeza, Freddy E. ; Peña O'Shea, Victor A. de la ; Gorni, Giulio ; Tian, C. M. ; Hofmann, Jan P. ; Cheng, Jun ; Li, Jun ; Zhang, Kelvin H. L. (2022)
Correlating the electronic structure of perovskite La₁₋ₓSrCoO₃ with activity for the oxygen evolution reaction: The critical role of Co 3d hole state.
In: Journal of Energy Chemistry, 65
doi: 10.1016/j.jechem.2021.06.032
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Perovskite LaCoO₃ is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction (OER). Sr doping in LaCoO₃ (La₁₋ₓSrCoO₃ ) has been found to substantially increase its catalytic activity. In this work, we report a detailed study on the evolution of the electronic structure of La₁₋ₓSrCoO₃ with 0 ≤ x ≤ 1 and its correlation with electrocatalytic activity for the OER. A combination of X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) was used to unravel the electronic density of states (DOS) near the Fermi level (EF), which provide insights into the key electronic structure features for the enhanced OER catalytic activity. Detailed analysis on the Co L-edge XAS suggest that LaCoO3 has a low spin state with t2g6eg0 configuration at room temperature. This implies that the high OER catalytic activity of LaCoO3 should not be rationalized by the occupancy of eg = 1 descriptor. Substituting Sr²⁺ for La³⁺ in LaCoO₃ induces Co⁴⁺ oxidation states and effectively dopes hole states into the top of valence band. A semiconductor-to-metal transition is observed for × ≥ 0.2, due to the hole-induced electronic DOS at the EF and increased hybridization between Co 3d and O 2p. Such an electronic modulation enhances the surface adsorption of the *OH intermediate and reduces the energy barrier for interfacial charge transfer, thus improving the OER catalytic activity in La₁₋ₓSrCoO₃ . In addition, we found that the La₁₋ₓSrCoO₃ surface undergoes amorphization after certain period of OER measurement, leading to a partial deactivation of the electrocatalyst. High Sr doping levels accelerated the amorphization process.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2022 |
| Autor(en): | Shen, Zechao ; Qu, Mei ; Shi, Jueli ; Oropeza, Freddy E. ; Peña O'Shea, Victor A. de la ; Gorni, Giulio ; Tian, C. M. ; Hofmann, Jan P. ; Cheng, Jun ; Li, Jun ; Zhang, Kelvin H. L. |
| Art des Eintrags: | Bibliographie |
| Titel: | Correlating the electronic structure of perovskite La₁₋ₓSrCoO₃ with activity for the oxygen evolution reaction: The critical role of Co 3d hole state |
| Sprache: | Englisch |
| Publikationsjahr: | 2022 |
| Ort: | Amsterdam |
| Verlag: | Elsevier |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Journal of Energy Chemistry |
| Jahrgang/Volume einer Zeitschrift: | 65 |
| DOI: | 10.1016/j.jechem.2021.06.032 |
| Kurzbeschreibung (Abstract): | Perovskite LaCoO₃ is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction (OER). Sr doping in LaCoO₃ (La₁₋ₓSrCoO₃ ) has been found to substantially increase its catalytic activity. In this work, we report a detailed study on the evolution of the electronic structure of La₁₋ₓSrCoO₃ with 0 ≤ x ≤ 1 and its correlation with electrocatalytic activity for the OER. A combination of X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) was used to unravel the electronic density of states (DOS) near the Fermi level (EF), which provide insights into the key electronic structure features for the enhanced OER catalytic activity. Detailed analysis on the Co L-edge XAS suggest that LaCoO3 has a low spin state with t2g6eg0 configuration at room temperature. This implies that the high OER catalytic activity of LaCoO3 should not be rationalized by the occupancy of eg = 1 descriptor. Substituting Sr²⁺ for La³⁺ in LaCoO₃ induces Co⁴⁺ oxidation states and effectively dopes hole states into the top of valence band. A semiconductor-to-metal transition is observed for × ≥ 0.2, due to the hole-induced electronic DOS at the EF and increased hybridization between Co 3d and O 2p. Such an electronic modulation enhances the surface adsorption of the *OH intermediate and reduces the energy barrier for interfacial charge transfer, thus improving the OER catalytic activity in La₁₋ₓSrCoO₃ . In addition, we found that the La₁₋ₓSrCoO₃ surface undergoes amorphization after certain period of OER measurement, leading to a partial deactivation of the electrocatalyst. High Sr doping levels accelerated the amorphization process. |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Oberflächenforschung |
| Hinterlegungsdatum: | 10 Mai 2024 13:58 |
| Letzte Änderung: | 11 Sep 2024 08:30 |
| PPN: | 518192989 |
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