Effect of temperature on the current-voltage characteristics of PdFe/Cu and NiCo/Cu bimetallic catalysts in alkaline alcohol electrolytes

Abstract

Abstract The temperature rise effect on the electrochemical activity of catalysts on a copper substrate in alkaline alcohol solutions has been studied. The object of research was bimetallic PdFe/Cu and NiCo/Cu catalysts obtained by galvanic deposition on a copper substrate. The studies were carried out in immiscible liquids EtOH + K2HPO4 + H2O. The upper phase in this system of liquids is aqueous solutions of ethanol (“alcohol layer”), the lower phase is aqueous solutions of dipotassium phosphate K2HPO4 (“salt layer”). It was found that elevate temperature from 20°C to 60°C improve the activity of all catalysts. It was found that the Ni80Co20/Cu catalyst is highly active in the oxidation and reduction of oxygen. The peak of the oxidation current increases 4 times with elevate the temperature up to 40 C, and 14 times with elevate temperature up to 60 C, compared with currents at a temperature of 20 C. The Pd90Fe10/Cu catalyst is active in relation to the oxidation of ethanol. Elevate the electrolyte temperature from 20°C to 40°C increase in the oxidation current by a factor of 1.4, and from 20°C to 60°C by a factor of 3.3. The maximum cathode current at the peak of recovery exceeds the maximum anode current at the peak of oxidation at 40°C by 1.83 times, and at 60°C by 1.15. This indicates a good regeneration of the electrode surface and the absence of oxide films and ethanol oxidation products on its surface. It was concluded that, despite the ambiguous effect of temperature on the processes occurring in the system, the improvement in the characteristics of the studied catalysts can be explained by the improvement in the processes of ethanol oxidation and improved mass transfer of the reagents.