Alkhalifah, Mohammed A., Howchen, Benjamin, Staddon, Joseph, Celorrio, Veronica, Tiwai, Devendra and Fermin, David J. (2022) Correlating Orbital Composition and Activity of LaMnxNi1-xO3 Nanostructures Towards Oxygen Electrocatalysis. Journal of the American Chemical Society, 144 (10). pp. 4439-4447. ISSN 0002-7863
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Abstract
The atomistic rationalization of the activity of transition metal oxides towards oxygen electrocatalysis is one of the most complex challenges in the field of electrochemical energy conversion. Transition metal oxides exhibit a wide range of structural and electronic properties, which are acutely dependent on composition and crystal structure. So far, identifying one or several properties of transition metal oxides as descriptors for oxygen electrocatalysis remains elusive. In this work, we performed a detailed experimental and computational study of LaMnxNi1-xO3 perovskites nanostructures, establishing an unprecedented correlation between electrocatalytic activity and orbital composition. The composition and structure of the single-phase rhombohedral oxide nanostructures are characterized by a variety of techniques, including X-ray diffraction, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and electron microscopy. Systematic electrochemical analysis of pseudocapacitive responses in the potential region relevant to oxygen electrocatalysis shows the evolution of Mn and Ni d-orbitals as a function of the perovskite composition. We rationalize these observations on the basis of electronic structure calculations employing DFT with HSE06 hybrid functional. Our analysis clearly shows a linear correlation between the OER kinetics and the integrated density of states (DOS) associated with Ni and Mn 3d states in the energy range relevant to operational conditions. On the other hand, the ORR kinetics exhibits a second-order reaction with respect to the electron density in Mn and Ni 3d states. For the first time, our study identifies the relevant DOS dominating both reactions and the importance of understanding orbital occupancy under operational conditions.
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| Additional Information: | Funding information: MA acknowledges the financial support from the Saudi Ministry of Education. BH is indebted by the financial support from the EPSRC Centre for Doctoral Training in Catalysis (EP/P016405/1). JS and DJF are thankful for the financial support provided by Johnson Matthey. The authors are grateful to Diamond Light Source for the access to the B18 beamline (SP10306). DT and DJF are grateful for the access to the high-performance computational facilities of the Advanced Computing Research Centre, University of Bristol - http://www.bris.ac.uk/acrc/. DT and DJF also acknowledge the support from EPSRC through the grants EP/V008692/1 and EP/V008676/1. The authors also acknowledge the EPSRC support via the capital grant EP/K035746/1, which contributed to the Electron Microscopy tools. XPS analysis was performed at the Bristol University NanoESCA Laboratory (Brunel). |
| Subjects: | F200 Materials Science G100 Mathematics |
| Department: | Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering |
| Depositing User: | John Coen |
| Date Deposited: | 02 Mar 2022 13:05 |
| Last Modified: | 07 Mar 2023 08:00 |
| URI: | https://nrl.northumbria.ac.uk/id/eprint/48590 |
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