Breathing-Mimicking Electrocatalysis for Oxygen Evolution and Reduction

Summary

Electrocatalytic oxygen evolution and reduction reactions play a central role in clean energy technologies. Despite recent efforts to achieve fast gas reactant delivery to the reaction interface, efficient gas product evolution from the catalyst/electrolyte interface remains challenging. Inspired by the mammalian breathing process, here we developed an efficient electrocatalytic system to enable ample gas-solid-liquid three-phase contact lines and bidirectional gas pathways for evolution and consumption. During the oxygen evolution reaction, the newly formed O₂ molecules quickly diffuse to the gas phase, waiving the bubble formation energy in the electrolyte. A record low overpotential of 190 mV at 10 mA⋅cm⁻² was achieved using Au/NiFeO_x catalysts. During the oxygen reduction reaction, O₂ gas can transport to the catalyst/electrolyte interface, overcoming low O₂ solubility in water and leading to ∼25-fold higher current densities for Ag/Pt bilayer nanoparticle catalysts. This breathing-mimicking design demonstrates efficient three-phase catalysis with a minimal catalyst thickness.