Wrinkled Strain‐Enriched High‐Entropy Metallene Enables Cross‐Site Tandem Nitrate‐to‐Ammonia

High‐entropy alloys (HEAs) are interesting for sustainable electrocatalytic nitrate‐to‐ammonia but suffer from low atom utilization and insufficient exposure of active sites. Here, we report a wrinkled PdFeCoNiCuIn high‐entropy metallene (HEM) that leverages a structural‐electronic dual regulation strategy to transcend these limitations. The incorporation of the p‐block element indium (In) triggers a strong p‐d orbital hybridization that synergizes with the intrinsic metallene architecture to construct a broad adsorption energy landscape. This architecture enables a cross‐site tandem catalytic pathway that spatially decouples nitrate activation from ammonia desorption, thereby circumventing scaling constraints. Consequently, the PdFeCoNiCuIn‐HEM delivers a remarkable ammonia Faradaic efficiency of 99.3% and a yield rate of 4.55 mmol h −1 mg cat −1 . Furthermore, the rechargeable Zn‐NO 3 − battery assembled with the PdFeCoNiCuIn‐HEM as cathode achieves a high open‐circuit voltage of 1.48 V, a power density of 7.36 mW cm −2 , and stable cycling over 100 h. This work provides a practical and generalizable design strategy for developing efficient NRA catalysts.