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Amorphous Co-Mo cathodes for hydrogen evolution

Wojciech Gagatek ,  Remigiusz Kowalik ,  Piotr Zabinski 

AGH University of Science and Technology (AGH), al. Mickiewicza 30, Kraków 30-059, Poland


Tailoring of active cobalt alloy cathodes for hydrogen evolution in hot concentrated sodium hydroxide solution was attempted by electrodeposition. Enhancement of cathodic activity of cobalt for electrolytic hydrogen evolution has been carried out by the formation of cobalt alloys containing molybdenum.

The present work aims to prepare the Co-Mo alloys with high cathodic activity for hydrogen evolution by electrodepositing. Also we try to clarify the effect of the molybdenum addition in enhancing the high activity for hydrogen evolution and changes of electrodeposits morphology.

The hydrogen evolution activity of the electrodes was examined in 8M NaOH solutions at 90oC by the galvanostatic polarization curves measurement. The structure of the deposited alloys was identified by XRD. According to X-ray diffraction patterns electrodeposited of Co-Mo alloys with high molybdenum content are amorphous.

When the molybdenum contents in the deposit are low, the linear dependence between logarithms of current density and potential is observed (Tafel dependence). It suggests that the rate-determining step was proton discharge on the cathode surface. The hydrogen evolution is mainly the same as for pure cobalt. If the alloys contain high molybdenum content and the surface is mostly amorphous alloy and the activity for hydrogen evolution is much higher. For those alloys we do not observed Tafel dependence. It means that proton discharging is so fast that rate-determining step seems to be desorption of hydrogen from the surface of the electrode after recombination of two discharged protons.

The authors express their acknowledgment for financial support under grant No. 3 T08B 016 29.


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium D, by Piotr Zabinski
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-04-16 12:34
Revised:   2009-06-07 00:44