Atomically Dispersed Zn and Ir Synergistic Modulation of Substrate and Active Sites for High‐Performance Ammonia Oxidation

A rationally designed, bifunctional ammonia‐oxidation catalyst spatially decouples NH 3 activation and *OH adsorption to overcome the intrinsic trade‐off of single‐component systems. Atomically dispersed Zn single atoms in an N,O‐doped carbon support (Zn 1 /NOC) serve as dedicated *OH‐adsorption sites, while Ir‐modulated Pt(100) nanocubes selectively activate NH 3 . Comprehensive structural characterization (AC HAADF‐STEM, XPS, XANES, EXAFS) confirms Zn‐N 3 O 3 coordination and atomically isolated Zn centers. Electrochemical‐kinetic analysis, mechanistic spectroscopy, and DFT calculations reveal that Zn 1 /NOC lowers the *OH‐adsorption energy by 0.84 eV (to −0.98 eV versus −0.14 eV on Pt), facilitating the dehydrogenation steps and reducing surface poisoning. Simultaneously, traces of stabilized Ir 4+ ‐decorated Pt cubes enhance NH 3 dissociation kinetics to form N 2 . The catalyst demonstrates a specific activity of 3.80 mA cm −2 PGMs , exceeding the state‐of‐the‐art benchmarks. When deployed in a membrane‐electrode‐assembly direct ammonia fuel cell, the catalyst achieves a maximum current density of 200 mA cm −2 and a peak power density of 18 mW cm −2 , representing a significant improvement over previously reported systems, with ∼250% increase over Pt np –C || Pt/C and more than double monofunctional systems. This work demonstrates a generalizable strategy for engineering spatially decoupled active sites in multistep electrochemical reactions, paving the way for high‐performance ammonia fuel cells and beyond.