LAUSR

Electrochemical nitrate reduction (NO3RR) to ammonia is a promising method for treating nitrate pollutant and potentially replacing the Haber‐Bosch process for ammonia production. High‐entropy nanoalloys (HEAs) show significant potential in catalyzing NO₃RR due to their compositional diversity, which results in a unique “cocktail” effect beneficial for the multistep NO3RR process. Herein, a high‐entropy alloy catalyst consisting of Co, Ni, Cu, Mn, and Fe elements is prepared through the pyrolysis of a high‐entropy Prussian blue precursor. After optimizing the elemental proportions, the Fe HEA catalyst exhibits exceptional NO3RR activity with an NH3 Faradaic efficiency (FE) of 92% and a yield rate of 3.25 mg h−1 cm−2. Moreover, the electrochemical hydrazine oxidation reaction (HzOR) is applied to construct a NO3RR‐HZOR flow cell. This cell system not only produces NH3, but also generates electricity, achieving a peak power density of 1.32 mW cm−2. Theoretical investigations show that the excellent performance of HEA can be attributed to the “cocktail” effect induced by multi‐element composition, which results in a lower work function and a negative shifting of the d band center, thus favoring the charge transfer and hydrogenation process of NO3RR. This work highlights the remarkable potential of HEAs for multistep chemical production and expands their applications in energy conversion and electrosynthesis.