Synthesis and properties of Au–TiO ₂ nanocomposites via pulsed laser ablation in liquid: Antibacterial and photocatalytic activity

This research presents an environmentally friendly preparation of gold-plated titanium oxide (Au–TiO 2 ) composites using pulsed laser ablation in liquid (PLAL) at different laser energies (200, 400 and 600[Formula: see text]mJ). The resulting plasma was experimentally characterized, and the results showed an increase in electron temperature from 0.47 eV to 0.90 eV and an increase in electron density from [Formula: see text] [Formula: see text]cm[Formula: see text] to [Formula: see text] [Formula: see text]cm[Formula: see text]. X-ray diffraction (XRD) confirmed the presence of two crystalline phases of gold (111) and titanium oxide ([Formula: see text]), with a decrease in crystal size from 22[Formula: see text]nm to 17[Formula: see text]nm. Field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) analysis revealed a homogeneous distribution of nanoparticles and a gradual increase in the amount of gold. Optical studies showed a clear absorption peak around 525[Formula: see text]nm resulting from surface plasmon resonance (SPR), while photoemission (PL) demonstrated high efficiency in charge separation and charge reduction. Photocatalytic tests under visible light showed a 90% degradation rate with a velocity of [Formula: see text]. Bacterial tests showed inhibition zones measuring [Formula: see text] [Formula: see text]mm for Staphylococcus aureus and [Formula: see text] [Formula: see text]mm for Escherichia coli. These results confirm that controlling plasma properties during the process contributes to achieving a balance between structural and optical properties, making Au–TiO 2 composites promising candidates for environmental and medical applications.