Elucidating activity-stability trade-offs in nano-fingerprint carbon anchoring single atoms and clusters in oxygen...

Hybrid sites (M_1+x) that incorporate single atoms (M₁) with clusters (M_x) hold great potential for overcoming linear scaling relations in electrocatalysis, but spatial decoupling of M₁ from M_x fundamentally hampers intercomponent synergy. Here, we report a composite electrocatalyst (Zn₁Fe_1+x/f-NC) featuring Fe_x clusters encapsulated within nano-fingerprint carbon layers and surrounded by densely dispersed Fe/Zn-N₄ atomic sites. Decoupling experiments revealed that Fe₁/Zn₁ atomic sites mainly initiate catalytic activity, while Fe_x clusters further boost intrinsic activity, whereas nano-fingerprint carbon facilitates the confinement and stabilization of M_1+x. The Zn₁Fe_1+x/f-NC demonstrates competitive oxygen reduction reaction performance, achieving a half-wave potential of 0.93 V and stability over 50 h. Zinc-air batteries with Zn₁Fe_1+x/f-NC air cathode exhibit a peak power density of 263.82 mW·cm^-2 and robust stability exceeding 2200 h at 10 mA cm^-2. Density functional theory calculations reveal that the atomic Zn sites, Fe_x clusters and nano-fingerprint carbon layers jointly enhance the catalytic activity and stability by modulating the electronic structure of Fe-N₄ sites and optimizing the adsorption energy of the key intermediate, especially OH*.