Fabrication of spinel NiCo2O4 nanoflowers by simple hydrothermal method for effective electrochemical detection of NO2− in processed food sample

This study introduces a novel, cost-effective, highly sensitive electrochemical sensor for detecting nitrite (NO₂^-) in processed food samples. The sensor was developed by fabricating spinel NiCo₂O₄ nanoflowers (NCO) using a hydrothermal method. Various characterization techniques, including XRD, FT-IR, XPS, HR-SEM, EDX, and HR-TEM, were used to analyze the structure and morphology of NCO. The obtained NCO exhibited a particle size of ∼16 nm and a flowered shape. Electrochemical impedance spectroscopy (EIS) was used to assess the electron-transfer properties. Cyclic voltammetry (CV) and chronoamperometry (CA) were employed to explore the electrocatalytic performance, revealing a high surface area and remarkable activity. The NCO electrode exhibited a remarkable sensitivity 44.16 μA mM^-1 cm^-2 at low concentrations and 33.51 μA mM^-1 cm^-2 at higher concentrations and a low detection limit of 0.99 μM. It is worth noting that the sensor displayed excellent reproducibility and repeatability, with relative standard deviation (RSD) values of 1.06 % and 1.37 %, respectively. Furthermore, the fabricated sensor was successfully applied for the detection of NO₂^- in milk, oranges, apple juice, wastewater, and processed foods such as chicken and sausage. The obtained results indicate that the proposed sensor is a promising candidate for practical NO₂^- detection applications.