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-NO₃ ^- 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.