A research group led by Prof. Junji Nakamura (Mitsui Chemicals, Inc.–Carbon Neutral Research Center) has reported on how to prevent the deactivation based on the mechanistic understanding that O₂+pyri-NH⁺+e⁻ → O₂a+pyri-NH governs the ORR kinetics. First, they considered that the deactivation is due to the hydration of pyri-NH⁺, leading to a lower shift of the redox potential. Introducing the hydrophobic cavity prevented the hydration of pyri-NH⁺ but inhibited the proton transport. They then increased proton conductivity in the hydrophobic cavity by introducing SiO₂ particles coated with ionic liquid polymer/Nafion® which kept the high onset potentials with an increased current density even in acidic media.
Singh S. K., Takeyasu K.*, Homma K., Ito S., Morinaga T., Endo Y., Furukawa M., Mori T., Ogasawara H., and Nakamura J.*, Activating Nitrogen-doped Graphene Oxygen Reduction Electrocatalysts in Acidic Electrolytes using Hydrophobic Cavities and Proton-conductive Particles, Angewandte Chemie International Edition. (2022). https://doi.org/10.1002/anie.202212506