Nanofibers decorated with high-entropy alloy particles for the detection of nitrites

Excessive residues of nitrite can pose a serious threat to human health, making the establishment of an efficient and effective electrochemical sensor for nitrite detection highly necessary. Herein, we report on a sensor based on nitrogen-doped carbon nanofibers, with FeCoNiCuAl high-entropy alloy (HEAs) nanoparticles <i>in situ</i> grown on the carbon fibers through a confinement effect. The FeCoNiCuAl/CNF sensor is capable of electrochemically detecting nitrite using both differential pulse voltammetry (DPV) and amperometric (<i>I</i>-<i>t</i>) methods. The DPV detection offers a linear range of 0.1-5000 μM and 5000-18 000 μM, with sensitivities of 150.6 μA mM^-1 cm^-2 and 80.1 μA mM^-1 cm^-2 and a detection limit of 0.023 μM (S/N = 3). The <i>I</i>-<i>t</i> detection covers a range of 1-10 000 μM, with a sensitivity of 337.84 μA mM^-1 cm^-2 and a detection limit of 0.12 μM. Moreover, the sensor exhibits excellent anti-interference properties, stability, and reproducibility, providing feasibility for nitrite detection in real-world environments.