Origin of Surface Amorphization and Catalytic Stability of Ca2- xIrO4Nanocrystals for Acidic Oxygen Evolution: Critical Roles of Acid Anions

Na Li, Liang Cai*, Guoping Gao, Yuying Liu, Chao Wang, Ziyi Liu, Qianqian Ji, Hengli Duan, Lin Wang Wang*, Wensheng Yan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Iridium-based perovskite oxides and complex oxides are being developed for efficient acidic oxygen evolution reaction (OER) electrocatalysts; however, the origin of their surface layer amorphization has remained poorly understood and the role of the surface amorphous layer for electrochemical OER performance is not clear. Here, we observe surface amorphization of Ca2-xIrO4nanocrystals during acidic OER in the H2SO4electrolyte, while there is no obvious surface amorphous state in the HClO4electrolyte, using scanning transmission electron microscopy imaging. The X-ray absorption near-edge structure (XANES) spectra reveal that a few CaSO4molecules are adsorbed on the Ca2-xIrO4surface in the H2SO4electrolyte, but the Ca coordination environments of the Ca2-xIrO4surface are almost unchanged in the HClO4electrolyte. Density functional theory calculations suggest that the Ca2IrO4surface with leached Ca atoms is responsible for the excellent acidic OER activity, and the strong binding strengths of SO42-and CaSO4on the surface of Ca2-xIrO4induce surface amorphization. Chronopotentiometric measurements indicate the critical role of acid anions for the long-term catalytic stability of Ca2-xIrO4nanocrystals in representative acidic electrolytes. Our results demonstrate the formation mechanism of surface amorphization on Ca2-xIrO4nanocrystal electrocatalysts and provide insights into the influence of different electrolytes on catalytic stability for highly active acidic OER nanocatalysts.

Original languageEnglish (US)
Pages (from-to)13475-13481
Number of pages7
JournalACS Catalysis
Issue number21
StatePublished - Nov 4 2022

Bibliographical note

Funding Information:
This work was financially supported by the National Key Research and Development Program of China (2021YFA1600800); the National Natural Science Foundation of China (Grant Nos. 11975234, 11775225, U2032150, U1932211, 12075243, 12005227, and 12105286); the Users with Excellence Program of Hefei Science Center, CAS (Nos. 2020HSC-UE002, 2020HSC-CIP013, 2021HSC-UE002, and 2021HSC-UE003); the Major Science and Technology Project of Anhui Province (202103a05020025); the Key Program of Research and Development of Hefei Science Center, CAS (2021HSC-KPRD002); the Fundamental Research Funds for the Central Universities (WK 2310000103); and the Postdoctoral Science Foundation of China (Grant Nos. 2022TQ0322, 2020M682041, and 2020TQ0316) and partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication. G.G. was supported by the “Young Talent Support Plan” of Xi’an Jiaotong University (Grant No. 11304222010715). L.-W.W. was supported by the Director, Office of Science, the Office of Basic Energy Science (BES), Materials Sciences and Engineering (MSE) Division of the U.S. Department of Energy (DOE) through the theory of material (KC2301) program under Contract No. DEAC02-05CH11231. The authors would like to thank Beijing Synchrotron Radiation Facility (BSRF), Shanghai Synchrotron Radiation Facility (SSRF), and Beamlines MCD-A and MCD-B (Soochow Beamline for Energy Materials) at NSRL for the synchrotron beamtime.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.


  • acidic OER electrocatalysis
  • impact of electrolyte anions
  • iridium-based complex oxides
  • surface amorphization mechanism

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry


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