Nanoflower‐Like CuPd/CuO Heterostructure for an Energy‐Output Electrocatalytic System Coupling Ammonia Electrosynthesis and Zinc‐Nitrate Battery

Abstract Electrochemical nitrate reduction reaction (NO 3 RR) can effectively alleviate nitrate pollution and simultaneously realize ammonia electrosynthesis at room temperature. However, it remains a significant challenge for NO 3 RR to achieve high Faradic efficiency in a full concentration range. Herein, nanoflower‐like copper‐palladium alloy/CuO heterostructure (CuPd/CuO@NF) is successfully fabricated by the hydrothermal synthesis of CuO nanoflowers and subsequent formation of CuPd alloy. The as‐obtained CuPd/CuO@NF exhibits remarkable electrochemical performance for NO 3 RR in the NO 3 − ‐N range from 20 to 1400 ppm, especially with NO 3 − conversion rate of 97.8% and NH 3 selectivity of 99.3% at 20 ppm, Faradic efficiency of 94.2% and NH 3 yield rate of 1.37 mmol h −1 cm −2 at 1400 ppm. In‐situ Fourier transform infrared spectroscopy and Raman spectra reveal that CuPd/CuO@NF first catalyzes NO 3 − reduction to NO 2 − , which is rapidly reduced to NH 3 by forming *NH, *NH 2 , and *NH 2 OH intermediates. Density functional theory calculations suggest that the NHO route is thermodynamically favorable. When CuPd/CuO@NF is applied in zinc‐nitrate battery, it demonstrates a maximum power density of 53.7 mW cm −2 , with NO 3 − conversion of 99.9% and Faradic efficiency of 94.4%. This work offers valuable insights into the design of novel NO 3 RR electrocatalysts and zinc‐nitrate batteries.