Photocatalytic activity of TiO₂-Carbon nanocomposite films against Culex pipiens mosquito larvae under sunlight irradiation

Recent research has focused on developing eco-friendly nanomaterials to combat mosquito infestations. This study demonstrates the enhancement of titanium dioxide (TiO₂) nanoparticles through the addition of carbon nanoparticles (C-NPs), significantly boosting their photocatalytic efficiency. This enhancement allows TiO₂ to purify water and act as an effective pesticide. Formulated TiO₂-carbon (TiO₂–C) nanocomposite films showed increased photocatalytic activity against third-instar larvae of Culex pipiens under natural sunlight. The addition of C-NPs improved sunlight absorption and reduced electron-hole recombination rates compared to pristine TiO₂ (P–TiO₂), making it more effective for mosquito control. The superior performance of the TiO₂–C nanocomposite was confirmed through X-ray Photoelectron Spectroscopy (XPS), UV–vis diffuse reflectance spectra (UV–vis DRS), and Photoluminescence emission (PL). These analyses confirmed successful carbon incorporation, expanding the absorption spectrum and enhancing optical properties. The UV–vis DRS spectra showed a decrease in the bandgap energy (Eg) of P–TiO₂ from 3.2 eV to 3.1 eV, improving its photocatalytic effectiveness under natural sunlight. Bioactivity tests, including catalase activity, reduced glutathione (GSH) colorimetric assay, and superoxide dismutase (SOD) assay, along with microscopic and histological examinations of treated larvae, indicated that the TiO₂–C nanocomposite effectively reduces the mosquito population and causes significant physiological damage and abnormalities in larval structures and midgut cells. These findings highlight the enhanced photocatalytic capabilities of the TiO₂–C nanocomposite, making it a novel and effective solution for mosquito control with significant public health and environmental benefits.