The Influence of the Cation on the Oxygen Reduction and Evolution Activities of Oxide Surfaces in Alkaline Electrolyte

Understanding the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) mechanisms is critical to the design of future electrocatalysts for fuel cells, electrolyzers, and metal-air batteries. As parts of the effort to elucidate the reaction mechanisms, we report the influence of the cationic species on the ORR/OER activity of select transition metal oxide catalysts in alkaline solutions. Specifically, we use Li+, Na+, and K+-containing electrolytes to assess the role of the cation on the ORR activity of Pt nanoparticles and LaMnO3+delta, as well as the OER activity of rutile IrO2 and Ba0.5Sr0.5Co0.8Fe0.2O3-delta. We found that all these benchmark electrocatalysts share the same cation trends, where the presence of the smaller cation (Li+) always leads to lower activity. We argue that this finding represents the possible cation influence on the ORR/OER intermediate stabilization.