Synergistic Silver–Carbon Quantum Dot Nanohybrids for Electrochemiluminescence Detection of Paraquat in Environmental Water

The development of a highly sensitive electrochemiluminescence (ECL) sensor for the detection of Paraquat (PQ), a toxic chemical widely used as herbicide, in water samples is presented. Silver nanoparticles enriched with nitrogen-doped carbon quantum dots (Ag NPs/N-CQDs) were prepared and employed forECL-based PQ sensing. The synergistic effect between Ag NPs and N-CQDs significantly enhances the ECL signal, enabling efficient electron transfer and stable luminescent output. The sensing concept is based on the quenching of ECL intensity of Ag NPs/N-CQDs luminophore in the presence of PQ. The optimized sensor exhibited a dynamic linear response in the range of 0.0013–25.70 μg ml −1 , with a low limit of detection (LOD) of 0.4 ng ml −1 , and excellent selectivity. The developed concept for PQ sensing presents a promising platform for the selective and ultrasensitive detection of herbicidal pollutants in complex matrices.