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Thickness dependent OER electrocatalysis of epitaxial thin film of high entropy oxide

Patel, RK and Jenjeti, RN and Kumar, R and Bhattacharya, N and Kumar, S and Ojha, SK and Zhang, Z and Zhou, H and Qu, K and Wang, Z and Yang, Z and Klewe, C and Shafer, P and Sampath, S and Middey, S (2023) Thickness dependent OER electrocatalysis of epitaxial thin film of high entropy oxide. In: Applied Physics Reviews, 10 (3).

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Official URL: https://doi.org/10.1063/5.0146005


High entropy oxides (HEOs), which contain multiple elements in the same crystallographic site, are a promising platform for electrocatalysis in oxygen evolution reaction (OER). Investigating these materials in epitaxial thin film form expands the possibility of tuning OER activity by several means, which are not realizable in polycrystalline samples. To date, very few such studies have been reported. In this work, the OER activity of single-crystalline thin films of (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)NiO3, grown on NdGaO3 substrates have been investigated in 0.1 M KOH electrolyte as a function of film thickness. The OER activity increases with the thickness of the film. X-ray absorption spectroscopy measurements find an increase in Ni d-O p covalency and a decrease in charge transfer energy with the increase in film thickness. These facilitate higher charge transfer between Ni and surface adsorbates, increasing OER activity. However, the OER process leads to excessive leaching of thicker films and the OER activity of a 75 unit cell thick film is found to be optimal in the present study. This work demonstrates that the thickness of perovskite oxides can be used as a parameter to enhance OER activity.

Item Type: Journal Article
Publication: Applied Physics Reviews
Publisher: American Institute of Physics Inc.
Additional Information: The copyright for this article belongs to the American Institute of Physics Inc.
Keywords: Charge transfer; Electrocatalysis; Electrolytes; Entropy; Film thickness; Gallium compounds; Lanthanum compounds; Neodymium compounds; Nickel; Nickel oxide; Potassium hydroxide; Thin films; X ray absorption spectroscopy, Crystallographic sites; Epitaxial thin films; Film-thickness; Multiple elements; Polycrystalline samples; Reaction activity; Single-crystalline thin films; Spectroscopy measurements; Thickness of the film; X-ray absorption spectroscopy, Perovskite
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 29 Nov 2023 09:10
Last Modified: 29 Nov 2023 09:10
URI: https://eprints.iisc.ac.in/id/eprint/82894

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