Operando Identification of Active Species and Intermediates on Sulfide Interfaced by Fe3O4for Ultrastable Alkaline Oxygen Evolution at Large Current Density

Qianqian Ji, Yuan Kong, Hao Tan, Hengli Duan, Na Li, Bing Tang, Yao Wang, Sihua Feng, Liyang Lv, Chao Wang, Fengchun Hu, Wenhua Zhang, Liang Cai, Wensheng Yan

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73 Scopus citations


Transition-metal sulfides are investigated as promising electrocatalysts for oxygen evolution reaction (OER) in alkaline media; however, the real active species remain elusive and the development of oxyhydroxides reconstructed from sulfides delivering stable large current density at low applied potentials is a great challenge. Here, we report a synergistic hybrid catalyst, composed of nanoscale heterostructures of Co9S8and Fe3O4, that exhibits only a low potential of 350 mV and record stability of 120 h at the 500 mA cm-2in 1.0 M KOH. Voltage-dependent soft X-ray absorption spectroscopy (XAS) and Operando Raman spectroscopy demonstrate that the initial Co9S8@Fe3O4is reconstructed into CoOOH/CoOx@Fe3O4and further to complete CoOOH@Fe3O4. Operando XAS and electron microscopy imaging analyses reveal that the completely reconstructed CoOOH acts as active species and Fe3O4components prevent the aggregation of CoOOH. Operando infrared spectroscopy indicates cobalt superoxide species (*OOH) as the active intermediates during the OER process. Density functional theory calculations demonstrate the formation of *OOH as the rate-determining step of OER and CoOOH@Fe3O4exhibits a lower energy barrier for OER. Our results provide an in-depth understanding of the dynamic surface structure evolutions of sulfide electrocatalysts for alkaline OER and insights into the design of excellent nanocatalysts for stable large current density.

Original languageEnglish (US)
Pages (from-to)4318-4326
Number of pages9
JournalACS Catalysis
Issue number8
StatePublished - Apr 15 2022

Bibliographical note

Funding Information:
This work was financially supported by the Excellence Program of Hefei Science Center CAS (Nos. 2019HSC-UE002, 2020HSC-UE002, and 2021HSC-UE002), the National Natural Science Foundation of China (Grants No. 11975234, 11775225, 12075243, 12005227, and U1932211), and the Fundamental Research Funds for the Central Universities (WK2310000103). Financial supports by the Postdoctoral Science Foundation of China (Grants No. 2020M682041 and 2020TQ0316) and the Ministry of Science and Technology of China (Grant No. 2017YFA0204904) are also acknowledged. This work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication. The authors would like to thank the Beijing Synchrotron Radiation Facility (BSRF), the 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.


  • large current density
  • nanoscale heterostructures
  • OER electrocatalysis
  • operando spectroscopy
  • surface reconstruction process
  • transition-metal sulfides

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry


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