Synergistic fusion of Zn-NB engineered 0-D carbon quantum dot matrix-modified GCE for ultrasensitive monitoring of water-contaminating 2-nitro-1,4-phenylenediamine.

Carbon-based materials are widely used in electrochemical applications due to their excellent conductivity and surface activity. In this work, a novel carbon quantum dots (CQDs) were used as a matrix to enhance the electrochemical properties of Zn-NB. The Zn-NB@CQD composite was successfully synthesized using a sonochemical method, where L-ascorbic acid served as the precursor for CQDs and Zn-NB was prepared through a one-pot hydrothermal process. The formation of the Zn-NB@CQD composite was confirmed through structural analyses such as XRD, Raman, and XPS, while its morphology was examined using SEM and TEM. The resulting composite was employed to modify a glassy carbon electrode (GCE), creating an efficient electrochemical sensor for selective detection of 2-nitro-1,4-phenylenediamine (2NPED). The Zn-NB@CQD modified electrode demonstrated a lower solution resistance of 87.25 Ω and charge transfer resistance is 77.82 Ω, indicating significantly improved conductivity compared to pristine materials and bare GCE. Square-wave and differential pulse voltammetry revealed a high sensitivity of 0.444 μAμM-1cm-2 within the linear range of 0.02-2800.4 μM. The LOD of Zn-NB@CQD is 2.200 μM. Real-sample analysis using river, wastewater, and tap water spiked with 100-500 μM of 2NPED yielded recovery values near 99 %, confirming the sensor's strong selectivity, minimal interference, and excellent reproducibility.