Encapsulation of CoS2 nanoparticles in 3D star-like N-doped graphitized carbon/carbon nanotubes nanocomposites for the detection of hydrazine in human urine and food

The design and construction of an efficient electrochemical hydrazine sensor is of great significance for food quality and safety detection. Herein, a novel three-dimensional (3D) hexagonal star-like carbon nanotubes modified N-doped graphitized carbon encapsulated CoS2 nanocomposites (CoS2 @NC/CNTs) was prepared using cobalt and zinc zeolitic imidazolate frameworks (CoZn-ZIF) as a precursor. The "tip effect" of the hexagonal star-like structure facilitates electron transfer and mass transfer. Carbon nanotube-modified N-doped graphitized carbon substrates (NC/CNTs) avoid agglomeration of CoS2 nanoparticles and have excellent electrical conductivity and abundant active sites. The above synergistic effects enable the CoS2 @NC/CNTs-based hydrazine electrochemical sensors to exhibit enhanced electrocatalytic activity compared to the conventional 3D ZIF-derived dodecahedral CoS2 @NC. As an electrochemical hydrazine sensor, CoS2 @NC/CNTs can provide a wide linear range of 1.0 μM - 6.0 mM, an excellent sensitivity of 2101 μA mM−1 cm −2, a detection limit as low as 96 nM (S/N = 3), a satisfactory stability and a promising selectivity. In addition, the sensor displays encouraging performance in the detection of hydrazine in biological and food samples, which lights up a new field for the application of such catalysts in electrochemical sensing.