Efficient and highly sensitive electrochemical histamine detection in fish on NiO/Cu/Cu2O heterojunction electrode with tunable oxygen vacancy density by electrodeposition technique

Electrochemical detection of histamine (HA) faces a significant challenge: the oxygen evolution reaction (OER) causes substantial background interference at the high potentials required for HA oxidation. To address this, a novel sensing platform was constructed based on an in-situ prepared NiO/Cu/Cu 2 O heterojunction electrode, where the oxygen vacancy (O v ) density was modulated via electrodeposition to significantly enhance catalytic activity. The unique methodological advance of this platform lies in leveraging the inherent Ni 2+ /Ni 3+ redox couple for indirect HA quantification, thereby completely circumventing OER interference. The fabricated sensor demonstrates exceptional performance, including ultra-high sensitivity (3.51 mA mM −1  cm −2 ), a low detection limit (0.044 nM), and a wide linear range (1 nM to 5 × 10 6  nM). Furthermore, the platform was successfully applied to detect HA in complex matrices (fish samples), yielding results consistent with high-performance liquid chromatography. This work demonstrates the platform's potential as a robust analytical tool for convenient, rapid, and highly sensitive HA detection in real samples.