Flower-like 3D MoS₂ microsphere/2D C₃N₄ nanosheet composite for highly sensitive electrochemical sensing of nitrite

Nitrite pollution poses a serious threat to human health and the environment. In this study, a reliable and selective electrochemical (EC) sensor was developed for the quantitative determination of nitrite by combining flower-like three-dimensional (3D) MoS₂ microspheres with two-dimensional (2D) C₃N₄ nanosheets. Benefiting from the synergistic effects of MoS₂ and C₃N₄, the 3D MoS₂/2D C₃N₄ nanocomposite displayed numerous active sites, a 3D mesoporous structure, high conductivity and excellent catalytic activity. The 3D MoS₂/2D C₃N₄-modified glassy carbon electrode (GCE) exhibited a superior electrocatalytic activity toward nitrite oxidation, with a wider linear detection range (0.1-1100 μM), a lower detection limit (LOD) (0.065 μM, S/N = 3), outstanding stability, remarkable reproducibility and strong selectivity. Furthermore, the nitrite EC sensor was successfully applied to detect actual food and environmental samples involving sausage, pickled vegetables, river water and tap water, thus demonstrating the potential of the prepared 3D MoS₂/2D C₃N₄/GCE for food analysis and environmental monitoring.