PLAIL-Synthesized Multifunctional Core Double-Shell Nanostructures for Photocatalytic, Antibacterial, and Self-Cleaning Surface Applications

This study investigates the synthesis, structural configuration, and multifunctional environmental performance of ZnO, CuO, and TiO 2 core double–shell nanostructures fabricated via Pulsed Laser Ablation in Liquid (PLAIL) at two distinct laser wavelengths (532 nm and 1064 nm). Three different oxide-layer sequences ZnO@CuO@TiO 2 , CuO@TiO 2 @ZnO and TiO 2 @ZnO@CuO were systematically engineered to assess the influence of composition and shell ordering on the nanoparticles’ optical absorption, energy band gap, morphology, surface roughness, wettability, photocatalytic activity, and antibacterial efficiency. UV–Vis spectroscopy revealed that samples synthesized at 532 nm exhibited superior optical absorption, with the CuO@TiO 2 @ZnO configuration displaying the broadest and most intense spectral response. Tauc plot analysis confirmed a significant dependence of the band gap on both wavelength and layer sequence, with the CuO@TiO 2 @ZnO structure showing the lowest Eg value (2.10 eV at 532 nm). AFM and TEM analyses highlighted the influence of shell order and laser energy on surface texture, particle size, and agglomeration, while contact angle measurements confirmed the hydrophilic nature of all samples (θ < 90°). The ZnO@CuO@TiO 2 nanostructure demonstrated the highest antibacterial efficiency against both Staphylococcus aureus and Escherichia coli, whereas the CuO@TiO 2 @ZnO structure achieved the best photocatalytic performance (up to 67.2% methylene blue degradation). These findings highlight the crucial role of both laser processing parameters and nanostructure configuration in tuning surface properties and enhancing multifunctional performance, offering promising potential for photocatalytic and self-cleaning antibacterial surfaces.