1：Experimental Design and Method Selection:

The method involves generating ligand-free CuOx or FeOx nanoparticles via pulsed laser ablation of metal oxide targets in water, followed by colloidal deposition onto anatase TiO2 substrate by adjusting pH to establish electrostatic attraction. This allows precise control over catalyst loading and size.

2：Sample Selection and Data Sources:

CuO and Fe2O3 micropowders from Sigma-Aldrich were used as ablation targets. Anatase TiO2 powder (Hombikat UV 100 from Sachtleben) served as the substrate. 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a test pollutant for photocatalytic degradation experiments.

3：List of Experimental Equipment and Materials:

Pulsed laser ablation system (Rofin Sinar RSM100D, 1064 nm), analytical disk centrifuge (CPS DC2400), zeta potential measurements (Malvern Zetasizer Nano ZS), XRD (STOE STADI-P diffractometer), UV-vis spectrophotometer (Perkin Elmer Lambda 650), SEM (LEO-1550 FE-SEM), TEM (Philips CM12, FEI Titan 80-300), photoluminescence spectrophotometer (Horiba Jobin Yvon Fluorolog), XPS (VersaProbe II), solar simulator (US-800, UNNASOL GmbH), spectrofluorometer (FluoroLog-3, Horiba Jobin Yvon). Materials include CuO, Fe2O3, TiO2, water (Milli-Q), nitric acid, NaOH, terephthalic acid, and 2,4-D.

4：Experimental Procedures and Operational Workflow:

Laser ablation was performed with specific parameters (30 W power, 6 mJ pulse energy, 5 kHz repetition rate) to generate colloids. pH was adjusted to 6 for deposition. Photocatalytic degradation of 2,4-D was conducted under simulated solar irradiation, with samples taken at intervals for UV-vis analysis. Hydroxyl radical production was measured via fluorescence of hydroxyterephthalic acid.

5：Data Analysis Methods:

Size distributions were analyzed using differential centrifugal sedimentation. Zeta potential measurements determined isoelectric points. Photocatalytic rates were calculated from concentration changes of 2,4-D. Statistical analysis included standard deviations from multiple experiments.