Electrochemical oxidation of H2S on polycrystalline Ni electrodes

Jian Yang, Vera Smulders, Joost J.T. Smits, Bastian T. Mei, Guido Mul*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Abstract: We have evaluated the applicability of Ni anodes in electrochemical conversion of H2S to form sulfur (polysulfides) and H2. Two different electrolytes containing sulfide were evaluated: a buffered solution of Na2HPO4 at pH 9.2, and a NaOH solution at pH 13. At pH 9.2, deposition of sulfur on the Ni anode was observed, resulting in a significant decrease in electrochemical performance. The composition, morphology, and thickness of the sulfur deposit, as determined by Raman spectroscopy and SEM, was found to strongly depend on the applied potential, and ranged from dense S8 films to highly porous spherical sulfur structures. Oxidation of the anode was also observed by conversion of Ni to NiS2. The formation of the sulfur film was prevented by performing the reaction at pH 13 in NaOH in the range of − 1.0 V to + 0.6 V versus Hg/HgO. It is proposed that at these highly basic pH values, sulfur is dissolved in the electrolyte in the form of polysulfides, such as S2 2− or S8 2−. When using Ni anodes some oxygen evolution was observed at the anode, in particular at pH 13, resulting in a Faradaic efficiency for sulfur removal of ~ 90%. Graphic Abstract: [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)929-936
Number of pages8
JournalJournal of applied electrochemistry
Volume49
Issue number9
Early online date22 Jul 2019
DOIs
Publication statusPublished - 15 Sep 2019

Keywords

  • UT-Hybrid-D
  • Basic conditions
  • HS
  • Ni anode
  • Phosphate buffer
  • Sulfide oxidation
  • Sulfide selectivity
  • Anode deactivation

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