Electrochemical stability of stainless-steel-made anode for alkaline water electrolysis: Surface catalyst nanostructures and oxygen evolution overpotentials under applying potential cycle loading

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Abstract

We investigated electrochemical stability of the NiFe-hydroxide/oxide-catalyst-layer covered stainless-steel(SS)-anode (NiFe-HyOx/SS) for alkaline water electrolysis. The NiFe-HyOx catalyst layer was synthesized through constant current density electrolysis of 30 mA/cm2 in 1 M KOH solution of a 316 SS plate at 75 ℃ for 5 h. The initial overpotential of oxygen evolution reaction (OER) was estimated to be ca. 270 mV at 100 mA/cm2 and the potential kept almost constant during applying the 20,000 potential cycles (PCs) of 0.5 and 1.8 V vs. reversible hydrogen electrode in 7 M KOH at 20 ℃. Scanning transmission electron microscopic observations conducted before and after the PCs loading revealed that the 50 nm-thick, nanofiber-like NiFe-HyOx catalyst layer remained unchanged in structure and in thickness, while the ca. 850 nm-thick, relatively dense NiFe-(hydro)oxide interlayer was generated under the catalyst layer. The results suggest that the superior OER property of the NiFe-HyOx/SS anode is originated from the surface catalyst layer.

Original languageEnglish
Article number106902
JournalElectrochemistry Communications
Volume122
DOIs
Publication statusPublished - 2021 Jan

Keywords

  • Alkaline water electrolysis
  • NiFe (hydro)oxide catalyst layer
  • Oxygen evolution reaction
  • Potential cycle loading
  • Stainless steel

ASJC Scopus subject areas

  • Electrochemistry

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