University of Oulu

Energy Fuels 2022, 36, 19, 12160–12169. Publication Date:September 14, 2022

Mechanism of iron integration into LiMn1.5Ni0.5O₄ for the electrocatalytic oxygen evolution reaction

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Author: Ahmed, Imtiaz1; Biswas, Rathindranath1; Dastider, Saptarshi Ghosh1;
Organizations: 1Department of Chemistry, Central University of Punjab, Bathinda, Punjab 151401, India
2Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan
3Indian Institute of Science Education and Research Kolkata, Nadia, West Bengal 741246, India
4Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra 400094, India
5Department of Physics, Central University of Punjab, Bathinda, Punjab 151401, India
6Nano and Molecular Systems Research Unit, University of Oulu, FI-90014 Oulu, Finland
Format: article
Version: accepted version
Access: embargoed
Persistent link:
Language: English
Published: American Chemical Society, 2022
Publish Date: 2023-09-14


Spinel-type LiMn1.5Ni0.5O₄ has been paid temendrous consideration as an electrode material because of its low cost, high voltage, and stabilized electrochemical performance. Here, we demonstrate the mechanism of iron (Fe) integration into LiMn1.5Ni0.5O₄ via solution methods followed by calcination at a high temparature, as an efficient electrocatalyst for water splitting. Various microscopic and structural characterizations of the crystal structure affirmed the integration of Fe into the LiMn1.5Ni0.5O₄ lattice and the constitution of the cubic LiMn1.38Fe0.12Ni0.5O₄ crystal. Local structure analysis around Fe by extended X-ray absorption fine structure (EXAFS) showed Fe3+ ions in a six-coordinated octahedral environment, demonstrating incorporation of Fe as a substitute at the Mn site in the LiMn1.5Ni0.5O₄ host. EXAFS also confirmed that the perfectly ordered LiMn1.5Ni0.5O₄ spinel structure becomes disturbed by the fractional cationic substitution and also stabilizes the LiMn1.5Ni0.5O₄ structure with structural disorder of the Ni²⁺ and Mn⁴⁺ ions in the 16d octahedral sites by Fe²⁺ and Fe³⁺ ions. However, we have found that Mn³⁺ ion production from the redox reaction between Mn⁴⁺ and Fe²⁺ influences the electronic conductivity significantly, resulting in improved electrochemical oxygen evolution reaction (OER) activity for the LiMn1.38Fe0.12Ni0.5O4 structure. Surface-enhanced Fe in LiMn1.38Fe0.12Ni0.5O₄ serves as the electrocatalytic active site for OER, which was verified by the density functional theory study.

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Series: Energy & fuels
ISSN: 0887-0624
ISSN-E: 1520-5029
ISSN-L: 0887-0624
Volume: 36
Issue: 19
Pages: 12160 - 12169
DOI: 10.1021/acs.energyfuels.2c02447
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: Imtiaz Ahmed and Harjinder Singh are thankful to the Council of Scientific and Industrial Research (CSIR) for awarding the CSIR–SRF fellowship. Rathindranath Biswas is thankful to the Department of Science and Technology (DST) for providing the INSPIRE fellowship for the Ph.D. programme [DST/INSPIRE Fellowship/(IF190052)].
Copyright information: © 2022 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy and Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see