Nanostructured Ruthenium-Titanium Oxides for Highly Active and Stable Oxygen Evolution Electrocatalysts

Proton-exchange membrane water electrolyzers produce high purity hydrogen from water and electricity and can be powered using renewable energy; however, the high material cost, limited global supply, and overpotential of iridium-based oxygen evolution reaction (OER) electrocatalysts result in high device costs (both up-front catalyst and input electricity costs). Ruthenium-based acidic OER catalysts have among the highest activities reported, which are higher than the activities of iridium-based catalysts. In addition, ruthenium has a significantly lower cost and higher global supply compared to iridium. Despite their advantages, ruthenium-based catalysts (both metallic and oxide forms) show higher degradation and less stability than iridium-based catalysts. Improving corrosion resistance while maintaining ruthenium activity is key to producing catalysts that are both highly active and long-lasting for clean hydrogen production via water electrolysis. To create highly active and stable acidic OER electrocatalysts, we have explored ruthenium-titanium oxide, Ru1-xTixOy, as a model system of the interaction of a highly stable and inactive metal (Ti) with a highly active, unstable metal (Ru) within an oxide structure. We evaluated different synthesis methods and thermal treatments to obtain ruthenium-titanium oxides with varied compositions and structures. The effect of altering the Ti ratio within ruthenium-titanium oxides on the structure and OER activity and stability were determined. Understanding how the interaction of active and inactive elements can influence the oxygen evolution reaction provides a pathway to develop electrocatalysts with higher activity, improved stable and lower cost.