Amorphous Co 2 O 3 /Crystalline Cu Interface Enables Ultra‐Rapid Nitrite Conversion for Integrated Cascade Electroreduction of Nitrate to Ammonia
Wenjing Cui, Yanjie Chen, Sichen Huo, Zhuang Cai, Shuang Shi, Huanyu Guan, Xinyu Wang, Jitao Li, Peng Gu, Jinlong Zou, Ying Dai, Lei WangABSTRACT
Given serious nitrate (NO 3 − ) pollution and the energy‐intensive nature of traditional ammonia (NH 3 ) synthesis, the electrocatalytic NO 3 − reduction reaction (NO 3 − RR) offers a green route for NH 3 production. Copper (Cu)‐based catalysts, although kinetically favorable for NO 3 − ‐to‐NO 2 − conversion, still suffer from sluggish *NO 2 reduction, resulting in poor NH 3 selectivity. Herein, a tandem catalysis strategy is adopted to fabricate a cobalt(III) oxide‐Cu heterostructure on nickel foam (Co 2 O 3 ‐Cu/NF) to enhance NO 3 − RR activity. Coordination distortion and asymmetry confirm the distinctive amorphous nature of Co 2 O 3 . Results from online differential electrochemical mass spectrometry, electron paramagnetic resonance, and theoretical calculations indicate that Cu dominates the conversion of NO 3 − to NO 2 − , while Co sites work in tandem to optimize the NO 2 − adsorption, reduce the decisive transformation barrier from *NO 2 to *NO, and facilitate water dissociation (producing *H) for N‐intermediate hydrogenation. Electrochemical kinetic tests confirm that Co 2 O 3 incorporation promotes the conversion of NO 3 − to NO 2 − and enhances the deep hydrogenation capability for rapidly transforming NO 2 − into other intermediates. Co 2 O 3 ‐Cu/NF achieves a high NH 3 yield rate of 90.45 ± 0.76 mg h −1 cm −2 and NH 3 Faradaic efficiency (FE‐NH 3 ) of 93.4% ± 2.5%. This work overcomes the inherent limitations of Cu‐based catalysts through crystalline‐amorphous dual‐site tandem synergy, offering new insights for developing NO 3 − RR technology.