Electrochemical stability of RuO2(110)/Ru(0001) model electrodes in the oxygen and chlorine evolution reactions

Andrey Goryachev, Marco Etzi Coller Pascuzzi, Francesco Carlà, Tim Weber, Herbert Over (Corresponding author), Emiel J.M. Hensen (Corresponding author), Jan Philipp Hofmann (Corresponding author)

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Abstract

RuO 2 is commercially employed as an anodic catalyst in the chlor-alkali process. It is also one of the most active electrocatalysts for the oxidation of water, relevant to electrochemical water splitting. However, the use of RuO 2 is limited by its low anodic stability under acidic conditions, especially at high overpotentials. In the present work, the electrochemical stability of model RuO 2(110)/Ru(0001) anodes was investigated in order to gain a deeper understanding of the relation between structure and performance in Cl 2 and O 2 evolution reactions (CER and OER, respectively). Online electrochemical mass spectrometry was used to determine the onset potential of CER and OER in HCl and H 2SO 4 electrolytes, respectively. The onset potential of OER was higher in HCl than in H 2SO 4 due to competition with the kinetically more favorable CER. A detailed stability evaluation revealed pitting corrosion of the electrode surface with exposure of Ru(0001) metal substrate concomitant with the formation of a hydrous RuO 2 in some areas regardless of the applied electrochemical treatment. However, despite local pitting, the RuO 2(110) layer preserves its thickness in most areas. Degradation of the electrode was found to be less severe in 0.5 M HCl due to a decrease in the faradaic efficiency of RuO 2 oxidation caused by competition with the kinetically more favorable CER.

Original languageEnglish
Article number135713
Number of pages11
JournalElectrochimica Acta
Volume336
DOIs
Publication statusPublished - 10 Mar 2020

Keywords

  • Chlorine evolution reaction
  • Electrocatalysis
  • Oxygen evolution reaction
  • Ruthenium dioxide
  • Stability

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