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.