Electrochemical Evaluation of Ni/RuO2 and Ni/RuO2/Mixed- Metal Oxide Coatings Electrodes toward Hydrogen Evolution Reaction in Alkaline Medium

Ni/RuO2 electrode was fabricated by electrochemical deposition from an acidic RuCl3 solution at room temperature, then annealing at 120oC for 150 min. Morphology characterization revealed a mud-crack structure and electrochemical investigations of Ni/RuO2 and Ni bare substrate indicated more activity of Ni/RuO2 toward hydrogen evolution reaction. Afterward, RuO2-TiO2 (20-80), RuO2-TiO2-IrO2 (20-60-20) and RuO2-TiO2-Ta2O5 (20-60-20) mol. % were constructed by sol gel and thermal decomposition at 450oC on previously prepared Ni/RuO2 substrates. SEM micrographs showed the most roughness for RuO2-TiO2-IrO2 coating. XRD analysis revealed the formation of solid solution structures between RuO2 by IrO2 and Ta2O5. Electrochemical studies, including activity and stability studies also revealed the excellent performance for RuO2-TiO2-IrO2 due to its more surface roughness and also stabilizing effect of IrO2 and RuO2 on each other.