Visible-light-driven photocatalytic degradation of toxic insecticide thiamethoxam using Ni-doped PbS nanoparticles under visible light irradiation

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The widespread use of the toxic insecticide Thiamethoxam (TMX) poses significant risks to environmental and human health, necessitating effective remediation methods. This study reports the successful synthesis of novel Nickel-doped Lead Sulfide (Ni-PbS) nanoparticles via a straightforward co-precipitation approach for the visible-light-driven photocatalytic degradation of TMX. Structural analysis confirmed that the Ni-PbS nanoparticles crystallize in a face-centred cubic structure. Morphological examination revealed a flower-like architecture composed of nanosheets. Optical studies showed a narrowed band gap of 2.2 eV, confirming visible-light responsiveness. X-ray photoelectron spectroscopy (XPS) further verified the presence of Pb 2+ , S 2- , and the successful incorporation of Ni 2+ into the PbS lattice. The Ni-PbS catalyst demonstrated significantly enhanced photocatalytic activity, achieving 78.93% TMX degradation within 210 min with a rate constant of 0.02225 min −1 . Optimal performance was observed at pH 3 and a catalyst loading of 0.5 g/L. The catalyst also exhibited excellent stability and reusability over five consecutive cycles. Scavenger studies revealed that valence band holes (h + ) and hydroxyl radicals (•OH) were the dominant reactive species driving the degradation. Overall, this work highlights Ni-PbS as a robust and efficient photocatalyst for the remediation of water contaminated with neonicotinoid insecticides.

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