Amorphous‐Engineered Pt Asymmetric Electric Fields for Enhanced Power Density in Fuel Cells

Abstract Amorphous‐crystalline engineering has emerged as a pivotal strategy for enhancing catalytic performance. However, its precise realization in ultrasmall systems (<3 nm) remains challenging, which impedes cross‐scale interactions between single atoms (SAs) and atomic clusters (ACs). Here, sub‐3 nm amorphous‐shell/crystalline‐core Pt nanoparticles (Pt NP*) are achieved on carbon black via atomic layer deposition (ALD), successfully constructing dual‐scale (Pt SA+NP* /CB, Pt SA+AC /CB) and tri‐scale (Pt SA+AC+NP* /CB) asymmetric systems for oxygen reduction reaction (ORR). Experiment and density functional theory (DFT) results reveal that Pt NP* not only displays optimal intrinsic ORR activity in single‐, dual‐, and tri‐scale synergy but also enables activation of ORR and H 2 O 2 conversion kinetics of other sites via size‐engineered asymmetric synergy. Consequently, the tri‐scale Pt SA+AC+NP* /CB exhibits three‐fold enhancement in Pt mass activity versus commercial Pt/C and remarkably low H 2 O 2 selectivity of 3.9%, outperforming dual‐scale Pt SA+NP* /CB and Pt SA+AC /CB. Meanwhile, Pt SA+AC+NP* /CB delivers a peak power density of 2.34 W cm −2 in fuel cell with stable operation at 500 mA cm −2 for 100 h. This work provides novel perspectives for multiscale synergistic effects functioned by amorphous engineering.