A novel electrochemical sensor for ultra-sensitive detection of nitrite based on the synergistic effect of surfactant and KTiTaO₅

Based on the layered semiconductor material potassium tantalum titanate, a novel layered nanocomposite, C₃F₇–Azo⁺/TiTaO₅, was successfully synthesized using the stripping/recombination method. The surfactant trans-[2 -(2,2,3,3,4,4,4-heptafluorobutylamino) ethyl]-{2-[4-(4-hexylbenzene-azo)-phenoxy] ethyl}—dimethylammonium, abbreviated as C₃F₇–Azo⁺Br⁻, served as the active center. The resulting composite was utilized to modify a glassy carbon electrode (GCE), forming the composite modified electrode C₃F₇–Azo⁺/TiTaO₅/GCE, which was employed for the electrochemical detection of nitrite. During the experiment, X-ray diffractometry, transmission electron microscopy, and energy dispersive spectroscopy were used to characterize the morphology, structure, and elemental composition of the prepared materials. The electrochemical properties of the modified electrode were evaluated through cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The results indicated that the composite electrode C₃F₇–Azo⁺/TiTaO₅/GCE exhibited smaller electrochemical impedance (341.4 Ω) and a larger electrochemical active area (0.107 cm²). It also displayed excellent sensitivity to nitrite, with a detection limit of 0.87 μM in the concentration range of 1.25–40.46 μM. Furthermore, the composite modified electrode C₃F₇–Azo⁺/TiTaO₅/GCE demonstrated exceptional stability and anti-interference capability and effectively detected nitrite in real samples, such as river water, with recovery rates ranging from 97.83 to 99.12%.