Enhanced photocatalytic and antibacterial activity of TiO₂ Quantum dots doped with Cerium/Chitosan for Environmental Remediation: Experimental and theoretical approaches

The co-precipitation approach was adopted to synthesize ternary nanocomposites composed of Cerium-Ce, Chitosan-CS, and TiO₂ quantum dots (QDs). Different Ce concentrations (2 and 4 wt %) were doped into the fixed amounts of CS and TiO₂ QDs. The purpose of the current work was to assess the antimicrobial and photocatalytic activities of Ce/CS-TiO₂. The XRD study confirmed the tetragonal structure of TiO₂, whereas the presence of dopants (CS and Ce) in TiO₂ resulted in a decrease in crystallite size. The microstructural examination of the composites through HR-TEM suggested the formation of quantum dot structures. FTIR revealed the functional groups presence in the synthesized product and absorption spectra were collected through UV–vis spectrophotometer accompanied redshift therefore, decreased in band gap energy of Ce and CS doped TiO₂ was observed. PL spectroscopy was used to identify trap locations and charge carrier migration. SEM-EDS analysis validated the presence of dopants in the product and confirmed elemental composition. After incorporating 2% Ce into CS-TiO₂, the MB dye dissolved considerably, dye degradation was of 97% in basic medium. Significant antibacterial activity was observed against both Staphylococcus aureus and Escherichia coli (S.A and E.A) bacteria. The adsorption energies of the CS/Ce–TiO₂ nanocomposites were investigated using density functional theory, revealing the formation of stable structures.