Revolutionising pesticide detection: a high-sensitivity electrochemical sensor with CdS/g-C3N4/MWCNTs for paraquat monitoring

Abstract

ABSTRACT Over a decade, the Malaysia National Poison Centre found that 40% of pesticide poisoning cases may be linked to excessive paraquat (PQ) in water, soil, or food, underscoring the widespread impact on public health and emphasising the importance of detecting even trace amounts of PQ residues in the environment. Thus, this study presents a novel electrochemical sensor based on multiwalled carbon nanotubes (MWCNTs) reinforced cadmium sulphide co-anchoring on graphitic carbon nitride (CdS/g-C3N4) nanocomposites for PQ detection. The CdS/g-C3N4 nanocomposite was successfully synthesised and characterised through FTIR, XRD, EDX, FESEM and TEM analysis. The modified electrode (CdS/g-C3N4/MWCNTs PE) exhibited improved electrocatalytic activity, as demonstrated by cyclic voltammetry (CV) and impedance spectroscopy. The CdS/g-C3N4/MWCNTs PE displayed a high CV peak and low Rct value which corresponded to a higher electron transfer rate, reduced charge transfer resistance and enhanced mass transport properties. The electrochemical sensor’s performance was evaluated for the detection of PQ, and it demonstrated a linear response in a range of 1.0 µM to 0.1 mM with a limit of detection of 0.14 μM. Furthermore, the sensor exhibited selectivity with a less than 16% potential interference from various organic chemicals and inorganic ions. The sensor’s applicability was tested by quantifying PQ in real water samples, showing excellent recovery percentages ranging from 98.9% to 102.0%. The developed electrochemical sensor provides a practical solution for the rapid and accurate monitoring of PQ levels in the environment. This work establishes the foundation for the development of a selective electrochemical sensor for pesticide analysis, addressing both public health and environmental concerns.