Title: Active Learning Accelerated Discovery of Stable Iridium Oxide Polymorphs for the Oxygen Evolution Reaction

Abstract

The discovery of high-performing and stable materials for sustainable energy applications is a pressing goal in catalysis and materials science. Understanding the relationship between a material’s structure and functionality is an important step in the process, such that viable polymorphs for a given chemical composition need to be identified. Machine-learning-based surrogate models have the potential to accelerate the search for polymorphs that target specific applications. Herein, we report a readily generalizable active-learning (AL) accelerated algorithm for identification of electrochemically stable iridium oxide polymorphs of IrO₂ and IrO₃. The search is coupled to a subsequent analysis of the electrochemical stability of the discovered structures for the acidic oxygen evolution reaction (OER). Structural candidates are generated by identifying all 956 structurally unique AB2 and AB3 prototypes in existing materials databases (more than 38000). Next, using an active learning approach, we find 196 IrO₂ polymorphs within the thermodynamic amorphous synthesizability limit and reaffirm the global stability of the rutile structure. We find 75 synthesizable IrO₃ polymorphs and report a previously unknown FeF₃-type structure as the most stable, termed α-IrO₃. To test the algorithms performance, we compare to a random search of the candidate space and report at least a 2-fold increase in themore » rate of discovery. Additionally, the AL approach can acquire the most stable polymorphs of IrO₂ and IrO₃ with fewer than 30 density functional theory optimizations. Analysis of the structural properties of the discovered polymorphs reveals that octahedral local coordination environments are preferred for nearly all low-energy structures. Subsequent Pourbaix Ir–H₂O analysis shows that α-IrO3 is the globally stable solid phase under acidic OER conditions and supersedes the stability of rutile IrO₂. Calculation of theoretical OER surface activities reveal ideal weaker binding of the OER intermediates on α-IrO₃ than on any other considered iridium oxide. We emphasize that the proposed AL algorithm can be easily generalized to search for any binary metal oxide structure with a defined stoichiometry.« less

Authors:

Flores, Raul A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-5047-2530"

Paolucci, Christopher  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-4506-9306"

Winther, Kirsten T.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1254-1165"

Jain, Ankit  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-8091-9129"

Torres, Jose Garrido  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1727-0862"

Aykol, Muratahan  ^[4];

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• Search DOE PAGES for ORCID "0000-0001-6433-7217"

Montoya, Joseph ^[4]; Nørskov, Jens K. ^[5]; Bajdich, Michal  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1168-8616"

Bligaard, Thomas ^[6]

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+ Show Author Affiliations

1. Stanford Univ., CA (United States). SUNCAT Center for Interface Science and Catalysis
2. Stanford Univ., CA (United States). SUNCAT Center for Interface Science and Catalysis; Univ. of Virginia, Charlottesville, VA (United States)
3. Stanford Univ., CA (United States). SUNCAT Center for Interface Science and Catalysis; Indian Inst. of Technology Bombay, Powai (India)
4. Toyota Research Institute, Los Altos, CA (United States)
5. Technical Univ. of Denmark, Lyngby (Denmark)
6. Technical Univ. of Denmark, Lyngby (Denmark); Stanford Univ., CA (United States). SUNCAT Center for Interface Science and Catalysis

Publication Date:

Thu Jun 18 00:00:00 EDT 2020

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1656769

Grant/Contract Number:  

AC02-76SF00515; SC0008685

Resource Type:

Accepted Manuscript

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Volume: 32; Journal Issue: 13; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Algorithms; Radiology; Crystal structure; Chemical structure; Stability