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Resolving atomistic structure and oxygen evolution activity in nickel antimonates

Rao, Karun K. and Zhou, Lan and Lai, Yungchieh and Richter, Matthias H. and Li, Xiang and Lu, Yubing and Yano, Junko and Gregoire, John M. and Bajdich, Michal (2023) Resolving atomistic structure and oxygen evolution activity in nickel antimonates. Journal of Materials Chemistry A, 11 (10). pp. 5166-5178. ISSN 2050-7488. doi:10.1039/d2ta08854a.

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The oxygen evolution reaction (OER) requires electrodes that are not only catalytically active, but also stable under harsh electrochemical environments to enable efficient, durable technologies. Our recent report of a stable amorphous Ni₀.₅Sb₀.₅O_z OER photoanode established Ni–Sb–O as an important system for computational understanding of both the structural and catalytic behavior of these complex oxides. In the present work we show that NiₓSb₁₋ₓO_z with x > 0.33 crystallizes into a previously unknown phase. Guided by experimental X-ray diffraction, we use density functional theory calculations to perform a prototype phase search to identify a broad family of stable and metastable mixed rutile and hexagonal-like phases for x = 0.33, 0.50, and 0.66 compositions. For the identified phases, we predict favorable oxygen vacancy formation energies for Ni-rich compositions under the reducing synthesis conditions which match measured Ni K-edge X-ray absorption spectra. The calculated overpotential for the most active site decreases with increasing Ni content, from 0.91 V (x = 0.33) to 0.49 V (x = 0.66), which captures the experimentally observed trend. We find the active site changes from the Ni–O–Sb bridge to a Ni–O–Ni bridge at increasing Ni concentrations, rather than the commonly studied singly under-coordinated sites. Finally, detailed Pourbaix analysis of the identified phases show excellent electrochemical stability, consistent with experimentally measured low metal ion concentrations in the electrolyte of photoelectrochemical cells. Collectively, our consideration of an ensemble of structures enables identification of the most catalytically prolific structural motifs, aiding the understanding of crystalline and amorphous catalysts and elucidating the co-optimization of activity and durability in nickel antimonates.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rao, Karun K.0000-0001-6695-6046
Zhou, Lan0000-0002-7052-266X
Lai, Yungchieh0000-0001-9392-1447
Richter, Matthias H.0000-0003-0091-2045
Li, Xiang0000-0002-3780-7735
Lu, Yubing0000-0002-5791-9697
Yano, Junko0000-0001-6308-9071
Gregoire, John M.0000-0002-2863-5265
Bajdich, Michal0000-0003-1168-8616
Additional Information:This material is primarily based on work performed by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award DE-SC0021266. XAS data collection (BL 9-3 and 7-3) was carried out at Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract DE-AC02-76SF00515. Computational resources were provided by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Author contributions. K. R. performed calculations under supervision of M. B. L. Z. synthesized and characterized materials with Y. Lai contributing electrochemical and M. R. contributing TEM analysis. X. L. and Y. Lu performed X-ray absorption spectroscopy measurements under supervision of J. Y. J. G. and M. B. supervised the research and coordinated the experimental and computational effort. The manuscript was written by K. R. and L. Z. with contributions from J. G. and M. B. using data from all authors. All authors have given approval to the final version of the manuscript. The authors declare no competing conflicts of interest, financial or otherwise. All atomic configurations and DFT calculated energies are available in CatalysisHub at
Group:Liquid Sunlight Alliance
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0021266
Department of Energy (DOE)DE-AC02-76SF00515
Department of Energy (DOE)DE-AC02-05CH11231
Issue or Number:10
Record Number:CaltechAUTHORS:20230214-87246900.12
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:119281
Deposited By: Research Services Depository
Deposited On:30 Mar 2023 15:20
Last Modified:30 Mar 2023 15:20

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