Enzyme-like adaptive Fe-oxo-Co motifs boost oxygen reduction reaction for efficient Zn-air batteries

Enzyme-like metal atomic site catalysts are promising alternatives of platinum group metals for oxygen reduction reaction (ORR) in fuel cell application. The local coordination structure at metal atomic sites plays a dominant role in optimizing the adsorption/desorption of oxygen intermediates to enhance ORR, but there is still a significant challenge in achieving. Herein, we report a type of stable and dynamically adjustable mono-oxygen-bridged asymmetric dual-atomic metal catalyst, in which the active Fe-oxo-Co motif demonstrates platinium-like ORR activity with a half-wave potential of 0.92 V vs. RHE in alkaline condition and a maximum power density of 228 mW·cm⁻² in Zn-air batteries. Theoretical calculations reveal that the Fe-oxo ligands can act as electron regulators for neighboring Co sites, which optimize and promote the d-orbitals of Co metal shift towards lower energy levels, thereby weakening the adsorption of oxygen species, facilitating the progress of the ORR. More interestingly, the Fe–oxo–Co bond will dynamically change its strength to adaptively facilitate the intermediate steps during the ORR process. The design strategy towards enzyme-like adaptive behavior of active Fe-oxo-Co motifs brings significant hope for achieveing high performance fuel cell cathode materials.