Improving the Electrolytic Hydrogen Production Using Co-Cu-Mo Based Ionic Activator

Abstract

Alkaline water electrolysis is used when there is a need for the efficient, on-site production of the high purity hydrogen and oxygen, especially when coupled to the renewable energy sources, such as wind and solar energy. Hydrogen produced in this way can be stored and transported for remote power generation in fuel cells. In order to expand commercialization of the alkaline electrolyzers, operating and capital costs should be reduced. High power consumption of the electrolytic process could be decreased by using more efficient electrode materials, keeping in mind its costs. This manuscript presents a contribution on the improved efficiency of the alkaline electrolytic production of hydrogen by in situ adding activating compounds directly into the electrolyte during the electrolytic process. New elec­trode material was formed, based on the mixture of co-deposition of Co and Cu complexes and Mo oxide, applied as activating compound i.e. ionic activator. Electrocatalytic efficiency of ternary system CoCuMo was studied using quasi-potentiostatic, galvanostatic and impedance spectroscopy techniques. The electrodeposited ionic activator on the plain nickel electrode, is shown to have a great influence on the kinetics of the hydrogen evolution reaction, lowering the overvoltage for about 300 mV at current density of 100 mA cm-2. Morphological investigations using SEM shows formation of the porous structure on the cathode resulting in significant increase of the surface area, and UV/VIS spectra of the electrolyte, recorded during the electrolytic process shows decreased concentrations of the ionic activators making a deposit on the surface of the Ni cathode. This ionic activator was applied in the laboratory alkaline electrolytic cell and we found that the energy requirements per mass unit of hydrogen produced is reduced for more than 20%, compared to non-activated system, when operated at elevated temperatures. The use of the in-situ activation with CoCuMo based activators added directly into alkaline electrolyte could be of great interest, since it offers simplified electrode preparation procedure and provides reduction in the alkaline electrolyzer operating cost. Figure 1