Eclipta prostrata leaf extract derived carbon dots integrated TiO₂ nanocomposites using for enhanced 4-nitrophenol reduction, antioxidant and antibacterial activity

Water contamination by organic pollutants and microbes causes serious environmental problem and risks the life of living things. 4-Nitrophenol is a major constituent of several industrial effluents can damage the health of human. This study presents the development of a titanium dioxide (TiO₂) nanoparticles integrated with carbon dots (CDs) of Eclipta prostrata leaf extract designed for the catalytic reduction of 4-nitrophenol in water and antibacterial applications. CDs/TiO₂ nanocomposites were synthesized via a green, hydrothermal method. The structural and morphological analysis were performed by X-ray diffraction and microscopic analysis. The optical properties and stability of CDs/TiO₂ nanocomposites was studied using UV–visible and zeta potential measurements. The CDs/TiO₂ nanocomposite exhibited concentration-dependent antioxidant activity, results 90–95% radical scavenging efficiency, compared with the performance of ascorbic acid at 125 µg/mL in both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power assays. Antibacterial studies showed strong activity against Staphylococcus aureus and Klebsiella pneumoniae, with zone of inhibition of 18.4 mm and 19.3 mm, respectively, at 50 µg/mL. The catalytic activity of CDs/TiO₂ nanoparticles were tested through the reduction of 4-nitrophenol (4-NP) into 4-aminophenol through hydrogenation. CDs/TiO₂ nanocomposites possess excellent catalytic activity in the reduction of nitrophenol, achieving near-complete conversion within 20 min with a rate of 0.168 min⁻¹ follows pseudo first order kinetic reaction. These findings suggest the enhanced catalytic and antibacterial property of CDs/TiO₂ nanocomposites can be potentially employed for the remediation of 4-NP and microbial contaminated water.