Bioinspired Cu+-Cu2+ heterojunction for enhanced ammonia electrooxidation to nitrite and nitrate

Operando ATR-SEIRAS, DEMS, and DFT reveal an NH 2 OH-mediated AOR pathway at an enzyme-mimicking interface. • Cu 2 NCN/CuO achieves 98.93% FE at 1.50 V vs. RHE and a NO X - yield rate of 249.3 μmol cm -2 h -1 at 1.70 V vs. RHE. • A regeneration strategy mitigates surface poisoning and enables recovery of the oxidized products as crystalline KNO 3 . Electrochemical ammonia oxidation reaction (AOR) provides a promising route for the synthesis of nitrite and nitrate (termed NO x − ) under mild conditions. However, the selective conversion of NH 3 to NO x − is kinetically limited by the conventional stepwise dehydrogenation pathway. Herein, we report an ammonia monooxygenase (AMO)-inspired Cu 2 NCN/CuO heterostructure catalyst, in which the [N C–N] 2− framework provides a charge-buffering effect to stabilize Cu + -related species under oxidative AOR conditions. This biomimetic architecture enables the selective oxidation of NH 3 to NO x − by promoting a hydroxylamine (NH 2 OH)-mediated pathway that features early-stage N–O bond formation. As a result, it achieves a NO x − Faradaic efficiency as high as 98.93% at 1.50 V vs. RHE, with a corresponding yield rate of 48.48 μmol cm −2 h −1 . Operando attenuated total reflection surface-enhanced infrared absorption spectroscopy, differential electrochemical mass spectrometry, and density functional theory calculations collectively reveal that this catalytic architecture facilitates NH 2 OH intermediate formation and lowers the energy barrier for its subsequent oxidation, thereby underpinning its outstanding NO x − selectivity. These findings demonstrate that the AMO-inspired catalytic architecture provides an effective strategy for achieving efficient NO x − electrosynthesis via an NH 2 OH-mediated pathway. Download: Download high-res image (161KB) Download: Download full-size image An AMO-inspired biomimetic Cu 2 NCN/CuO heterostructure enables the selective conversion of NH 3 to NO 2 − and NO 3 − via an NH 2 OH-mediated pathway featuring early N–O bond formation.