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Bulletin of Materials Science

, Volume 23, Issue 5, pp 383–391 | Cite as

Kinetics of hydrogen evolution reaction on Zr0.5Ti0.5V0.6Cr0.2Ni1.2 alloy in KOH electrolyte

  • Shalini Rodrigues
  • N. Munichandraiah
  • A. K. Shukla
Article

Abstract

A hydrogen-storage alloy of the composition Zr0.5Ti0.5V0.6Cr0.2Ni1.2 has been investigated for corrosion resistance and hydrogen-evolution reaction (HER) in KOH electrolyte of varying concentrations. Activation of the electrode by absorption of hydrogen takes place after prolonged cathodic polarization in the potential range of HER. Prior to activation, the open-circuit potential is about −0.4 V vs Hg/HgO, OH, at which the alloy electrode tends to undergo corrosion with oxygen-reduction reaction (ORR) as the conjugate reaction. The corrosion-current density measured from Tafel polarization of ORR is found to be independent of KOH concentration and has an average value of about 30 μA cm−2. Subsequent to activation, the open circuit potential of the electrode is shifted to about −0.93 V vs Hg/HgO, OH, which is equal to the reversible potential of HER. The exchange current density values measured from Tafel polarization of HER are marginally higher in relation to the values obtained before the electrode is activated. Alternating-current impedance spectra in the Nyquist form contain two overlapped semicircles. The high-frequency semicircle is attributed to the electrode geometry, while the low-frequency semicircle is due to the charge-transfer reaction and double-layer capacitance. The impedance data are analyzed by a non-linear least square curve fitting technique and impedance parameters are evaluated.

Keywords

Hydrogen-storage alloy hydrogen-evolution reaction Tafel polarization a.c. impedance exchange-current density 

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Copyright information

© Indian Academy of Sciences 2000

Authors and Affiliations

  • Shalini Rodrigues
    • 1
  • N. Munichandraiah
    • 1
    • 2
  • A. K. Shukla
    • 1
  1. 1.Solid State and Structural Chemistry UnitIndian Institute of ScienceBangaloreIndia
  2. 2.Department of Inorganic and Physical ChemistryIndian Institute of ScienceBangaloreIndia

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