Toward an Active and Stable Catalyst for Oxygen Evolution in Acidic Media: Ti-Stabilized MnO₂

Catalysts are required for the oxygen evolution reaction, which are abundant, active, and stable in acid. MnO₂ is a promising candidate material for this purpose. However, it dissolves at high overpotentials. Using first-principles calculations, a strategy to mitigate this problem by decorating undercoordinated surface sites of MnO₂ with a stable oxide is developed here. TiO₂ stands out as the most promising of the different oxides in the simulations. This prediction is experimentally verified by testing sputter-deposited thin films of MnO₂ and Ti-MnO₂. A combination of electrochemical measurements, quartz crystal microbalance, inductively coupled plasma mass spectrometry measurements, and X-ray photoelectron spectroscopy is performed. Small amounts of TiO₂ incorporated into MnO₂ lead to a moderate improvement in stability, with only a small decrease in activity. This study opens up the possibility of engineering surface properties of catalysts so that active and abundant nonprecious metal oxides can be used in acid electrolytes.