1：Experimental Design and Method Selection:

The study used a modified polymer complex method for synthesis, involving citric acid and ethylene glycol with cerium nitrate precursor, heated and stirred, followed by pH adjustment and heat treatments. Characterization techniques included XRD, SEM, TEM, Raman, UV-Vis absorption, diffuse reflectance, photoluminescence, and XPS spectroscopies to analyze structural and optical properties.

2：Sample Selection and Data Sources:

Samples were synthesized at different pH values (e.g., pH ~1, 2, 9.1) and subjected to heat treatments at 550°C for 3 hours. A total of 17 samples were analyzed.

3：1) and subjected to heat treatments at 550°C for 3 hours. A total of 17 samples were analyzed. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included X-ray diffractometer (Pro PANalytical X’Pert X-ray), TEM (Jeol JEM-1200EX), SEM (EVO MA10, Carl Zeiss), Raman spectrometer (Thermo Scientific DXR SmartRaman), UV-Vis spectrophotometer (Thermo Scientific Genesys 6 and Jasco V-670), photoluminescence setup with Ar+ and Xenon lasers, and XPS system (SPECS with Phoibos 150 analyzer). Materials included cerium nitrate (Ce(NO3)3·6H2O, Alfa Aesar), citric acid (Merck), ethylene glycol (Mallinckrodt), ammonium hydroxide (Merck), and distilled water.

4：Experimental Procedures and Operational Workflow:

Synthesis involved mixing precursors, heating at 100°C, adjusting pH with NH4OH, high-shear treatment (Ultraturrax T50), heating to form resin, pre-calcination at 350°C, and final calcination at 550°C. Characterization steps included sample preparation (e.g., dispersion for TEM), data collection using specified instruments, and data analysis with software like Fityk, MAUD, and CasaXPS.

5：Data Analysis Methods:

Data were analyzed using Scherrer equation for crystal size, Kubelka-Munk transform for band gap, deconvolution of spectra with Gaussian functions, and XPS peak fitting for oxidation states.