Surface galvanic formation of Co-OH on Birnessite and its catalytic activity for the oxygen evolution reaction

Yayun Pu, Veronica Celorrio, Jöerg M. Stockmann, Oded Sobol, Zongzhao Sun, Wu Wang, Matthew J. Lawrence, Jörg Radnik, Andrea E. Russell, Vasile-dan Hodoroaba, Limin Huang, Paramaconi Rodriguez

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Abstract

Low-cost, high-efficient catalysts for water splitting can be potentially fulfilled by developing earth-abundant metal oxides. In this work, surface galvanic formation of Co-OH on K0.45MnO2 (KMO) was achieved via the redox reaction of hydrated Co2+ with crystalline Mn4+. The synthesis method takes place at ambient temperature without using any surfactant agent or organic solvent, providing a clean, green route for the design of highly efficient catalysts. The redox reaction resulted in the formation of ultrathin Co-OH nanoflakes with high electrochemical surface area. X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the changes in the oxidation state of the bulk and surface species on the Co-OH nanoflakes supported on the KMO. The effect of the anions, such as chloride, nitrate and sulfate, on the preparation of the catalyst was evaluated by electrochemical and spectrochemical means. XPS and Time of flight secondary ion mass spectrometry (ToF-SIMS) analysis demonstrated that the layer of CoOxHy deposited on the KMO and its electronic structure strongly depend on the anion of the precursor used during the synthesis of the catalyst. In particular, it was found that Cl- favors the formation of Co-OH, changing the rate-determining step of the reaction, which enhances the catalytic activity towards the OER, producing the most active OER catalyst in alkaline media.
Original languageEnglish
Pages (from-to)304-314
Number of pages11
JournalJournal of Catalysis
Volume396
Early online date5 Mar 2021
DOIs
Publication statusPublished - Apr 2021

Bibliographical note

Funding Information:
This work was financially supported by Southern University of Science and Technology (SUSTech) start fund through Shenzhen Peacock Talent program, Guangdong Provincial Key Laboratory of Energy Materials for Electric Power (2018B030322001), Guangdong Provincial Key Laboratory of Catalysis (2020B121201002), Shenzhen Clean Energy Research Institute (CERI-KY-2019-003), and Shenzhen Key Laboratory of Solid State Batteries (ZDSYS20180208184346531). P.R. acknowledges the University of Birmingham for financial support through the Birmingham fellowship program and the travel fund to perform experiments at BAM. TEM, Raman data were obtained using equipment maintained by Southern University of Science and Technology Core Research Facilities. The authors wish to acknowledge the Diamond Light Source for provision of beamtime (SP21659 and SP19850). YP, PR and LH conceived the experiments. YP performed the experiments and analyses the data. EXAFS characterization and analyses were performed by VC, ML and AER. XES data were collected and analyzed by VC and AER. STEM characterization was performed by WW and ZS. JMS and JR performed the XPS experiments in BAM and OS performed the ToF-SIMS experiments at BAM. All authors contributed to the analysis of the results, discussion, writing and revision of the manuscript. All authors have given approval to the final version of the manuscript.

Publisher Copyright:
© 2021 Elsevier Inc.

Keywords

  • Oxygen evolution reaction
  • Surface galvanic synthesis
  • Layered manganese oxide
  • Anion effect

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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