Abstract
The interaction between catalyst surfaces and adsorbed oxygen intermediates is critical to catalytic performance for electrochemical water oxidation to oxygen. However, the relationship between adsorption energetics and electrocatalytic activity is primarily assessed for pristine catalyst materials, which leaves much unknown about the dynamics of these properties in relationship to catalyst performance during long-term operation. In this work, we experimentally assess OH and O adsorption on Ca2IrO4 nanoparticles and monitor their evolution during extensive chronoamperometry tests at highly oxidizing potentials in a range of low pH electrolytes. In situ x-ray absorption spectroscopy reveals changes for surface adsorbate energetics and local iridium structures with applied potentials. Increasingly unfavorable adsorption of OH and formation of O intermediates after long-term operation is correlated with severe metal dissolution, distorted [IrO6] octahedral linkages, and a decreased average Ir valence. This work establishes connections between surface adsorption energetics, Ir structure, OER kinetics, and material stability outcomes.
| Original language | English (US) |
|---|---|
| Article number | 115387 |
| Journal | Journal of Catalysis |
| Volume | 431 |
| DOIs | |
| State | Published - Mar 2024 |
Funding
This work made use of the Jerome B. Cohen X-Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation ( DMR-2308691 ) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology This work made use of the EPIC and Keck-II facilities of Northwestern University’s NUANCE Center, which has received support from the SHyNE Resource ( NSF ECCS-2025633 ), the IIN, and Northwestern's MRSEC program ( NSF DMR-1720139 ). Experimental (SHyNE) Resource ( NSF ECCS-1542205 ). Metal analysis was performed at the Northwestern University Quantitative Bioelement Imaging Center (QBIC) generously supported by the NIH under grant S10OD020118 . The authors graciously acknowledge the assistance of Rebecca Sponenburg with metal analysis at QBIC. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357 . Hard XAS measurement was performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by Northwestern University, The Dow Chemical Company, and DuPont de Nemours, Inc. The authors also graciously acknowledge the help of Denis Keane and Qing Ma for their assistance with XAS experimentation at the 5-BM-D Advanced Photon Source. This material is based upon work supported by a National Science Foundation CAREER Award ( 2144365-CBET ).
Keywords
- Dynamic Materials
- Electrocatalysis
- Iridium
- Oxygen Evolution Reaction
- Stability
- Surface Adsorbates
ASJC Scopus subject areas
- Catalysis
- Physical and Theoretical Chemistry