1：Experimental Design and Method Selection:

The study involved synthesizing TiO2 and Ce-TiO2 photocatalysts via sol–gel method, characterizing them using XRD, Raman spectroscopy, BET surface area analysis, TEM, EDX, H2-TPR, UV-visible diffuse reflectance, and PL spectroscopy. Photocatalytic degradation experiments were conducted under UV light with H2O2, and degradation products were identified using LC/MS.

2：Sample Selection and Data Sources:

Sulfur black dye was purchased from Clariant. Aqueous solutions of the dye at various concentrations (50-400 ppm) were used.

3：List of Experimental Equipment and Materials:

Equipment includes autoclave (Equilabo), XPERT-PRO diffractometer, DILOR RTI 30 Raman spectrometer, MICROMERITICS ASAP 2020 surface area analyzer, Tecnai G20 UltraTwin TEM, ThermoFinnigan 1100 TPD/R/O gas chromatograph, Perkin-Elmer UV-visible spectrometer, Perkin-Elmer Lambda S55 spectrofluorometer, UV lamp (Apelex, VL-15C), SHIMADZU UV-1800 spectrophotometer, Agilent 1100 LC/MS, and centrifuge. Materials include titanium(IV) isopropoxide, cerium(III) nitrate hexahydrate, ethanol, ethylacetoacetate, nitric acid, hydrogen peroxide, and sulfur black dye.

4：Experimental Procedures and Operational Workflow:

Photocatalysts were synthesized via sol–gel, calcined, and characterized. For photocatalytic experiments, catalyst was dispersed in dye solution, stirred in dark for 30 min, irradiated with UV light, samples withdrawn at intervals, centrifuged, and analyzed by spectrophotometry and LC/MS.

5：Data Analysis Methods:

Color removal percentage calculated from absorbance measurements. Degradation products identified by interpreting mass spectra from LC/MS.