Construction of iron porphyrin/titanoniobate nanosheet sensors for the sensitive detection of nitrite

The single-layered well-dispersed HTi2NbO7 nanosheets (NSs) with the thickness of ~ 1.08 nm were obtained by a simple exfoliation method. The electrochemical sensors based on HTi2NbO7 NSs and 5,10,15,20-tetrakis (N-methylpyridinium-4-yl) porphyrinato iron(III) (FeTMPyP) for sensitive detection of nitrite were then fabricated through the self-assembly technique, which was certified by Zeta potential analysis. The prepared samples were fully characterized by X-ray diffraction, X-ray energy dispersive spectrometer, scanning electron microscope, atomic force microscope, high-resolution transmission electron microscope, Fourier transform infrared and ultraviolet–visible spectrum. Electrochemical measurements demonstrated that FeTMPyP/HTi2NbO7 NSs nanocomposites exhibited enhanced electrocatalytic activities toward the oxidation of nitrite due to increased electron-transport properties. The oxidation peak current of nitrite was linearly associated with its concentration in the range from 0.0999 to 3.15 mmol L−1, with the detection limit of 3.15 × 10−5 mol L−1 (S/N = 3). The possible mechanism for nitrite oxidation on the surface of modified electrode was proposed. This study indicated that this biosensor has satisfactory stability, and detects nitrite in wastewater with strong anti-interference performance and good recovery.