Tuning the Optical, Structural and Photocatalytic Properties of Copper Oxide Nanoparticles Synthesized via Pulsed Laser Ablation in Liquid for Environmental and Optoelectronic Applications

Copper oxide nanoparticles (CuO NPs) were synthesized by pulsed laser ablation in deionized water at different laser pulse energies. The optical response was examined for samples prepared at 600[Formula: see text]mJ, 800[Formula: see text]mJ, 1000[Formula: see text]mJ and 1200[Formula: see text]mJ, while selected samples were further evaluated for structural, photocatalytic and photodetector performance. XRD analysis confirmed the formation of monoclinic CuO, with an average crystallite size of approximately 47.31[Formula: see text]nm for the 1200[Formula: see text]mJ sample. TEM observation showed nearly spherical primary nanoparticles with an average size of about 16[Formula: see text]nm, whereas FESEM analysis of CuO deposited on porous silicon showed larger surface features of about 40[Formula: see text]nm, indicating that the measured size depends on the characterization method and sample form. UV–Vis analysis showed an increase in absorption intensity with laser energy, and the apparent optical bandgap estimated from Tauc plots decreased from [Formula: see text][Formula: see text]eV to [Formula: see text][Formula: see text]eV as the laser energy increased from 600[Formula: see text]mJ to 1200[Formula: see text]mJ. Photoluminescence analysis of the 1200[Formula: see text]mJ sample showed emission components near 428[Formula: see text]nm, 486[Formula: see text]nm and 590[Formula: see text]nm, suggesting contributions from near-band-edge, radiative recombination and defect-related transitions. For photocatalysis, CuO NPs prepared at 600[Formula: see text]mJ, 1000[Formula: see text]mJ and 1200[Formula: see text]mJ degraded methylene blue by 89.9%, 91.2% and 92.3%, respectively, after 120[Formula: see text]min under UV irradiation. The CuO/porous-Si photodetector showed increased photocurrent and responsivity compared with bare porous silicon, with the 1200[Formula: see text]mJ sample giving a responsivity of 0.136[Formula: see text]A[Formula: see text]W[Formula: see text] at 450[Formula: see text]nm under the reported measurement conditions. These results indicate that laser pulse energy influences the structural and optical properties of PLAL-synthesized CuO NPs and their potential use in photocatalytic and photodetection applications.