Hanging meniscus configuration for characterizing oxygen-reduction electrocatalysts in highly concentrated electrolytes

•Hanging meniscus configuration method was newly developed for porous catalysts.•This method evaluates oxygen reduction activity in highly concentrated electrolyte.•This method complements conventional rotating disk electrode (RDE) method. Oxygen reduction reaction (ORR) in metal-air batteries or fuel cells often require highly concentrated electrolyte for higher conductivity and electrochemical stability. However, conventional rotating disk electrode (RDE) method is ineffective to evaluate ORR activity in the real systems, because the scarce dissolved oxygen in highly concentrated electrolyte fails to provide significant ORR on RDE. Herein, we report a hanging meniscus configuration method for evaluating the electrocatalytic activity in highly concentrated electrolyte solutions, utilizing atmospheric oxygen through the triple-phase boundary. The newly developed method evaluated the ORR activity of silver and platinum catalysts in highly concentrated KOH electrolyte for zinc-air batteries, enabling the characterization in more realistic experimental condition.