Effect of Base on the Facile Hydrothermal Preparation of Highly Active IrOx Oxygen Evolution Catalysts

Jonathan Ruiz Esquius, David J. Morgan, Ioannis Spanos, Daniel G. Hewes, Simon J. Freakley, Graham J. Hutchings

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The efficient electrochemical splitting of water is limited by the anodic oxygen evolution reaction (OER). IrO2 is a potential catalyst with sufficient activity and stability in acidic conditions to be applied in water electrolyzers. The redox properties and structural flexibility of amorphous iridium oxo-hydroxide compared to crystalline rutile-IrO2 are associated with higher catalytic activity for the OER. We prepared IrOx OER catalysts by a simple hydrothermal method varying the alkali metal base (Li2CO3, LiOH, Na2CO3, NaOH, K2CO3, KOH) employed during the synthesis. This work reveals that the surface area, particle morphology, and the concentration of surface hydroxyl groups can be controlled by the base used and greatly influence the catalyst activity and stability for OER. It was found that materials prepared with bases containing lithium cations can lead to amorphous IrOx materials with a significantly lower overpotential (100 mV @ 1.5 mA·cm-2) and increased stability compared to materials prepared with other bases and rutile IrO2. This facile method leads to the synthesis of highly active and stable catalysts which can potentially be applied to larger scale catalyst preparations.

Original languageEnglish
Pages (from-to)800-809
Number of pages10
JournalACS Applied Energy Materials
Issue number1
Early online date5 Dec 2019
Publication statusPublished - 27 Jan 2020


  • amorphous iridium oxo-hydroxide
  • electrocatalysis
  • hydrothermal synthesis
  • iridium oxide
  • oxygen evolution reaction

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Materials Chemistry
  • Electrical and Electronic Engineering


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