1：Experimental Design and Method Selection:

The study involved a three-step process for synthesizing modified titanium dioxide nanocrystalline coatings on polypropylene (PP) foil: surface activation with low-temperature oxygen plasma, immobilization of TiO2 nanoparticles via dip-coating, and sensitization by impregnation with organic ligands. The rationale was to create visible light-active photocatalytic coatings with good adhesion to polymers.

2：Sample Selection and Data Sources:

Transparent PP films (0.1 mm thickness) from Goodfellow were used. Samples were cleaned with distilled water and ethanol before plasma activation. Organic modifiers included catechol, 2,3-naphthalenediol, pyrogallol, and rutin.

3：1 mm thickness) from Goodfellow were used. Samples were cleaned with distilled water and ethanol before plasma activation. Organic modifiers included catechol, 2,3-naphthalenediol, pyrogallol, and rutin. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a low-pressure oxygen plasma system (Zepto, Diener Electronic Plasma Surface Technology), dip coater (MTI Corporation), XPS spectrometer (Prevac with VG SCIENTA R3000 analyzer), UV-vis spectrophotometer (Shimadzu UV-3600), SEM (Tescan Vega3 LMU), AFM (Bruker Dimension ICON), FT-IR spectrometer (Thermo Scientific Nicolet 6700), and electrochemical analyzer (Autolab PGSTAT 302N). Materials included TiO2 nanoparticles (Nanostructured and Amorphous Materials, anatase, 5-30 nm), oxygen gas (Air Products, 99.5% purity), and various chemicals from Sigma-Aldrich.

4：5% purity), and various chemicals from Sigma-Aldrich. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: PP foils were plasma-treated (30-300 s, RF 40 Hz, power 100 W, oxygen pressure <0.3 mbar), then dip-coated with TiO2 colloidal solution (1.5 wt%, withdrawal speed 1 cm/min), dried at room temperature, impregnated with organic ligand solutions (10 mmol dm-3 for 5 min), washed, and dried. Photoactivity was tested via photocurrent measurements using ITO electrodes in a three-electrode setup with irradiation from a xenon lamp and monochromator.

5：3 mbar), then dip-coated with TiO2 colloidal solution (5 wt%, withdrawal speed 1 cm/min), dried at room temperature, impregnated with organic ligand solutions (10 mmol dm-3 for 5 min), washed, and dried. Photoactivity was tested via photocurrent measurements using ITO electrodes in a three-electrode setup with irradiation from a xenon lamp and monochromator. Data Analysis Methods:

5. Data Analysis Methods: XPS data were analyzed using CasaXPS software. Contact angles and surface free energy were calculated using the Owens-Wendt method. SEM and AFM were used for morphological analysis, and UV-vis spectra for optical properties.