rGO/HfO₂ nanocomposite-enabled electrochemical sensor for high-performance pesticide detection

This study applies a periodic table-guided approach to select and investigate hafnium oxide (HfO₂), in conjunction with reduced graphene oxide (rGO), for the electrochemical determination of methyl parathion (MP), an organophosphate insecticide. MP poses significant ecological and health risks due to its high toxicity, and despite bans, illegal use has been reported, especially in the global south. To address these challenges, an electrode modified with a nanocomposite of rGO/HfO₂ was first constructed for MP detection. Its analytical performance was evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The rGO/HfO₂ nanocomposite demonstrated effective adsorption of MP and facilitated electron transfer for enhanced sensitivity. Characterization via SEM and FT-IR confirmed the successful in-situ reduction of GO and the strong interaction between HfO₂ and MP. The sensor exhibited superior electrocatalytic activity compared to those using individual materials. Various detection techniques, including DPV, amperometry, and stripping voltammetry, were employed for MP detection. In DPV and stripping voltammetry, the peak current at -0.6 V was used to establish the calibration curve, while a fixed potential of -0.6 V (vs. Ag/AgCl) was applied for amperometry. DPV exhibited the best performance, with a limit of detection of 2.36 ppb. Moreover, the sensor displayed excellent selectivity in the presence of potential interferents, and validation through MP detection in spiked real water samples demonstrated its potential applicability for environmental monitoring.