A novel ZIF-67@g-C₃N₄–based colorimetric sensor with large hierarchical structure and enhanced surface area for sensitive detection of nitrite in drinking water

The detrimental effects of nitrite (NO₂⁻) on environment as well as living organisms have attracted immense interest to sensitively detect it in the drinking water system. So, for this purpose, we have developed a highly sensible and portable colorimetric NO₂⁻ sensor based on the CZ-2 nanocomposite (NC). The three dimensional (3D) with large hierarchical structure CZ-2 NC sensor was formed by the coupling of g-C₃N₄ nanosheets (NSs) and ZIF-67 nanoparticles (NPs) by a simple hydrothermal process. The prepared sensor was successfully employed to detect NO₂⁻, which manifests higher sensing characteristics like extensive sensitivity with large detection linear range of (1 × 10⁻³–7.20 × 10⁻¹ μM) having a R² of 0.999 and a lowest limit of detection (LOD) value of 0.16 ± 0.05 nM. Further, it also manifests excellent reversibility, better stability and durability, optimal reproducibility and superior repeatability. In addition, the sensor also depicts large selectivity towards NO₂⁻ and improved practicability in real water sampling. These commendable sensing properties were mainly ascribed to the large conductive structure and highest surface area of the CZ-2 NC structure. Thus, as a result, we analyzed that our fabricated colorimetric sensor was highly potent, its applications in the sensing fields can be explored for future perspective.