электрохимическая активность

Electrochemical activity of the electrodes with electrocatalytic coatings

Electrochemical activity of electrodes for electrolysis of water is investigated. As catalysts coating Ni-S-Co, suspension LaNi2.5Co2.4Al0.1 or their combinations were applied. As electrolyte at test of electrodes 30% KOH or NaOH is used. Current density varied in a range from 10 to 600 мА/cm2 at temperature 20-80°C. When the temperature increases from 20 to 80°C the current density on cathodes with composite LaNi2.5Co2.4Alo.i/Ni-S-Co catalyst increases 4 times at constant potential E = –1.10 V (rel. Hg/HgO). When the current density of more than 100 mA/cm2 cathodes with all catalysts offered by us in this work have lower value of potential than the similar cathodes described in the scientific literature. In contrast to the cathodes, catalyst LaNi2.5Co2.4Al0.1/Ni–S–Co does not render influence on electrochemical activity of the anode.

Development of the effective ways of the activation of the anodes for water electrolysis

Electrochemical activity of anodes on the basis of a nickel mesh grid for water electrolysis is investigated. Activation of anodes was made by three ways:
1) chemical covering sulfur-containing compounds of nickel and iron;
2) immersing in solution Na2S2O3 + H2SO4 (till pH=3);
3) immersing in solution Na2S + H2SO4 (till pH=3).
The water solution 6M KOH was used as the electrolyte while the electrodes testing. Current density varied in a range from 1 to 600 mAJ cm2 at temperature 20, 50 and 70°C. The greatest electrochemical activity have anodes activated by the third method. The anode potential at current density 600 mA/cm2 and temperature 70°C is equal +0.57 V (concerning Hg/HgO – the comparison electrode).

Electrochemical activity of the cathodes with platinum or platinum-palladium electrocatalysts for alkaline water electrolysis

Electrochemical activity of cathodes with Pt or Pt-Pd-electrocatalysts was studied by voltammetry method under galvanostatic conditions. The dependence of the overvoltage of hydrogen evolution reaction on the logarithm of current density and on the test time of the cathode with Pt-Pd-electrocatalysts are defined. It is shown that the electrochemical activity of cathode with Pt-Pd-electrocatalyst is two times higher than with Pt-electrocatalyst at the hydrogen evolution reaction in 30% KOH solution at 90°C. As the temperature increases from 15 to 90° C the current density at 40 mV overvoltage at the cathode with Pt-Pd-electrocatalyst increases by 8 times. The test results with this cathode electrocatalyst in the laboratory electrolyzer at a current density of 400 mA/cm2 and 65° C temperature within 11 days of intermittent regime work confirm the overvoltage stability in time.

Electrochemical activity of the cathodes with chemical coatings Ni-S-Fe

The electrochemical activity of nickel mesh cathodes activated by electrocatalysts of chemically deposited coatings Ni-S-Fe is investigated. The maximum reduction of overvoltage at current density 6 kA/m2 and temperature 70°C is 0.34 V. Comparison of the electrochemical activity of such cathodes with similar cathodes described in the scientific literature revealed that at the same temperature and same overvoltage the current density is twice higher than for the known electrodes. It is shown that with increasing temperature from 20 to 90°C overvoltage at the current density 4kA/m2 reduced by 110mV. Testing of the electrodes with electrocatalysts Ni-S-Fe in the laboratory electrolyser for 850 hours of continuous operation at current density 12kA/m2 indicate the stability of their electrochemical activity.