Two-step hydrothermal and ultrasound-assisted synthesis of CB/NiCo2S4@CeO2 composites for high-sensitivity electrochemical detection of nitrite.

A composite material (NiCo 2 S 4 @CeO 2) containing NiCo 2 S 4 and CeO 2 was synthesized by a two-step hydrothermal method, and the material was physically mixed with carbon black (CB) to fabricate a nitrite sensor based on CB/NiCo 2 S 4 @CeO 2 composites. [Display omitted] • NiCo 2 S 4 successfully grown on the surface of CeO 2 sphere through a hydrothermal method. • Carbon black as a conductive agent to fabricate CB/NiCo 2 S 4 @CeO 2 based nitrite sensors. • The abundant surface ionic valence and the multi-component synergy promote the rapid catalytic oxidation of nitrite. • The sensor exhibited remarkable catalytic performance in detecting nitrite. A composite material (NiCo 2 S 4 @CeO 2) containing NiCo 2 S 4 and CeO 2 was synthesized, and the material was physically mixed with carbon black (CB) to fabricate a nitrite sensor based on CB/NiCo 2 S 4 @CeO 2 nanocomposites. The composition and morphology of the composite material were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray electron spectroscopy (XPS). The evidence revealed that the material is spherical and consists of a composite of two compounds, NiCo 2 S 4 and CeO 2 , with NiCo 2 S 4 successfully grown on the CeO 2 surface. The results of cyclic voltammetric electrochemical experiments showed that CB/NiCo 2 S 4 @CeO 2 /GCE (E p = 0.78 V, I p = 145.6 μA) showed significant electrocatalytic performance against nitrite compared with GCE (E p = 0.96 V, I p = 66.7 μA). The analytical performance of the sensor proposed in this paper was investigated using the amperometric method, and the results were that the proposed nitrite sensor has a linear range of 0.2–7400 μM, and a sensitivity of 470 μA mM-1cm−2, and a detection limit of 0.003 μM. Compared with the similar type of nitrite sensors previously reported, the linear range of the sensors is broadened to 5 orders of magnitude. In addition, the sensor maintained 90.38% of its initial response after 30 days of storage in air at room temperature. The sensor was used in the recovery experiments of actual samples of tap water and mineral water, and good results were obtained. Therefore, CB/NiCo 2 S 4 @CeO 2 would be a promising electrode material for nitrite detection. [ABSTRACT FROM AUTHOR]