1：Experimental Design and Method Selection:

The study used a hydrothermal method assisted by calcination to synthesize TiO2–ZnO binary oxide systems with a molar ratio of 8:

2：Zinc citrate was used as the ZnO precursor. Calcination was performed at 500, 600, and 700°C to improve crystalline structure. Sample Selection and Data Sources:

Materials were synthesized and labeled as TiZn (hydrothermal only), TiZn_500, TiZn_600, and TiZn_700 based on calcination temperature. Model organic pollutants (C.I. Basic Red 1, C.I. Basic Violet 10, C.I. Basic Blue 3, 4-nitrophenol) were used for photocatalytic tests.

3：List of Experimental Equipment and Materials:

Equipment included SEM (EVO40, Zeiss), TEM (Jeol 1200 EX II, Jeol), XRD (D8 Advance, Bruker), Raman spectroscopy (Bruker Bravo), DRS (Thermo Scientific Evolution 220), EDXRF (Epsilon1, PANalytical), BET analyzer (ASAP 2020, Micromeritics), FT-IR (Vertex 70, Bruker), photocatalytic reactor (UV-RS2, Heraeus), UV-Vis spectrophotometer (V-750, Jasco), stirrer (Eurostar Digital, Ika Werke), peristaltic pump (ISM833A, ISMATEC), autoclave, calcination furnace (Nabertherm P320 Controller). Materials included titanium(IV) isopropoxide, zinc citrate dihydrate, propan-2-ol, ammonium hydroxide, and organic dyes from Sigma-Aldrich and Chempur.

4：Experimental Procedures and Operational Workflow:

Synthesis involved mixing TTIP and IPA, adding zinc citrate solution, stirring, hydrothermal treatment at 200°C for 24h, filtering, washing, drying at 60°C, and calcining. Characterization included SEM, TEM, XRD, Raman, DRS, EDXRF, BET, and FT-IR analyses. Photocatalytic tests involved adding photocatalyst to pollutant solution, stirring in dark for 30min, irradiating with visible light for up to 360min, sampling, centrifuging, and measuring concentration changes with UV-Vis.

5：Data Analysis Methods:

Photocatalytic degradation yield was calculated using a formula based on concentration changes. Kinetics were analyzed using the Langmuir–Hinshelwood model with pseudo-first-order reaction assumptions, and rate constants and half-lives were determined.