In-situ activated hydrogen evolution by molybdate addition to neutral and alkaline electrolytes

  • John Gustavsson Applied Electrochemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE 100 44 Stockholm
  • Christine Hummelgård Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, SE 851 70 Sundsvall
  • Joakim Bäckström Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, SE 851 70 Sundsvall
  • Inger Odnevall Wallinder Department of Surface and Corrosion Science, KTH Royal Institute of Technology, SE 100 44 Stockholm
  • Seikh Mohammed Habibur Rahman Department of Chemical and Biological Engineering, Chalmers University of Technology, SE 412 96 Gothenburg
  • Göran Lindbergh Applied Electrochemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE 100 44 Stockholm
  • Sten Eriksson Department of Chemical and Biological Engineering, Chalmers University of Technology, SE 412 96 Gothenburg
  • Ann Cornell Applied Electrochemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE 100 44 Stockholm

Abstract

Activation of the hydrogen evolution reaction (HER) by in-situ addition of Mo(VI) to the electrolyte has been studied in alkaline and pH neutral electrolytes, the latter with the chlorate process in focus. Catalytic molybdenum containing films formed on the cathodes during polarization were investigated using scanning electron microscopy (SEM), energy-dispersive X‑ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), and X‑ray fluorescence (XRF). In-situ addition of Mo(VI) activates the HER on titanium in both alkaline and neutral electrolytes and makes the reaction kinetics independent of the substrate material. Films formed in neutral electrolyte consisted of molybdenum oxides and contained more molybdenum than those formed in alkaline solution. Films formed in neutral electrolyte in the presence of phosphate buffer activated the HER, but were too thin to be detected by EDS. Since molybdenum oxides are generally not stable in strongly alkaline electrolyte, films formed in alkaline electrolyte were thinner and probably co-deposited with iron. A cast iron‑molybdenum alloy was also investigated with respect to activity for HER. When polished in the same way as iron, the alloy displayed a similar activity for HER as pure iron.

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Published
30-08-2012
Section
Electrochemical Science