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

Hybrid sites (M 1+x ) that incorporate single atoms (M 1 ) with clusters (M x ) hold great potential for overcoming linear scaling relations in electrocatalysis, but spatial decoupling of M 1 from M x fundamentally hampers intercomponent synergy. Here, we report a composite electrocatalyst (Zn 1 Fe 1+x / f -NC) featuring Fe x clusters encapsulated within nano-fingerprint carbon layers and surrounded by densely dispersed Fe/Zn-N 4 atomic sites. Decoupling experiments revealed that Fe 1 /Zn 1 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 Zn 1 Fe 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 Zn 1 Fe 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-N 4 sites and optimizing the adsorption energy of the key intermediate, especially OH*.