Title: Characterization of a Dynamic Y ₂ Ir ₂ O ₇ Catalyst during the Oxygen Evolution Reaction in Acid

Abstract

We report reducing precious metal content and improving the efficiency of proton exchange membrane water electrolyzers is critical for producing renewable hydrogen cost-effectively. Mixed metal iridium oxide catalysts (AIr_xO_y, A = nonprecious metal) have demonstrated superior oxygen evolution reaction (OER) activity relative to IrO₂ catalysts while utilizing less Ir. However, improved stability is required if these materials are to be implemented commercially. In this work, we use a combination of ex situ and in situ characterization techniques to study physical and electronic properties of Y₂Ir₂O₇ as it evolves during OER in acidic electrolyte. We identify and quantify dissolution of Y and Ir, finding that this material exhibits similar stability to other reported mixed metal Ir oxides (10⁴–10⁵ mol_{O2 evolved}/mol_{Ir dissolved}) and appears to become more stable over time. We find that the catalyst surface becomes enriched with Ir after electrochemical testing. We further monitored the Ir oxidation state in situ using high-energy resolution fluorescence detected X-ray absorption spectroscopy. Our results suggest that the Ir oxidation state is dynamic: an IrO_x surface forms that is more oxidized than the bulk pyrochlore material but subsequently dissolves. Such detailed characterization of material properties can be used to develop design principles for improving catalystmore » stability.« less

Authors:

Hubert, McKenzie A.  ^[1];

• Search DOE PAGES for author "Hubert, McKenzie A."
• Search DOE PAGES for ORCID "0000-0002-9987-0748"

Gallo, Alessandro  ^[2];

• Search DOE PAGES for author "Gallo, Alessandro"
• Search DOE PAGES for ORCID "0000-0003-4687-8188"

Liu, Yunzhi  ^[3];

• Search DOE PAGES for author "Liu, Yunzhi"
• Search DOE PAGES for ORCID "0000-0003-0524-4023"

Valle, Eduardo ^[1]; Sanchez, Joel ^[1]; Sokaras, Dimosthenis ^[4]; Sinclair, Robert ^[3]; King, Laurie A.  ^[5];

• Search DOE PAGES for author "King, Laurie A."
• Search DOE PAGES for ORCID "0000-0002-0772-2378"

Jaramillo, Thomas F.  ^[6]

• Search DOE PAGES for author "Jaramillo, Thomas F."
• Search DOE PAGES for ORCID "0000-0001-9900-0622"

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+ Show Author Affiliations

1. SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
2. SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
3. Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
4. SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
5. Faculty of Science and Engineering, Manchester Metropolitan University, Manchester M1 5GD, United Kingdom
6. SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States, SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States

Publication Date:

Fri Jan 21 00:00:00 EST 2022

Research Org.:

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

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Science Foundation (NSF)

OSTI Identifier:

1857996

Alternate Identifier(s):

OSTI ID: 1873511

Grant/Contract Number:  

AC02-76SF00515; ECCS-1542152; DGE-1656518

Resource Type:

Published Article

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Name: Journal of Physical Chemistry. C Journal Volume: 126 Journal Issue: 4; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY