1：Experimental Design and Method Selection:

The study involved synthesizing ZnO-Bi2O3-xC3N4 heterojunction catalysts (x=0,1,2,3) and evaluating their photocatalytic activity in degrading Indigo carmine under visible light with H2O2 assistance. A first-order kinetic model was applied to analyze degradation rates.

2：Sample Selection and Data Sources:

Indigo carmine dye solution (50 mg/L) was used as the pollutant. Catalysts were synthesized based on previous reports, and experiments were performed in triplicate.

3：List of Experimental Equipment and Materials:

Equipment included a Xenon lamp (150 W, Model No. LS 150 SN 332, ABET Technologies, USA) for visible light irradiation, a UV-Vis spectrophotometer (Thermo Evolution 201, U.S.) for concentration measurements, and a TOC analyzer (Shimadzu TOC-VCPH, Japan) for mineralization analysis. Materials included ZnO-Bi2O3-xC3N4 catalysts, H2O2, ethanol, ascorbic acid, and doubly distilled water.

4：Experimental Procedures and Operational Workflow:

For each experiment, 50 mg catalyst was added to 100 mL Indigo carmine solution at pH

5：After 60 min in dark for adsorption-desorption equilibrium, the suspension was irradiated with visible light. Samples were taken at intervals, and Indigo carmine concentration was measured at 612 nm. Effects of catalyst loading, pH, H2O2 concentration, and scavengers were investigated. Data Analysis Methods:

Data were analyzed using first-order kinetics (ln(C0/Ct) = kt) to determine rate constants. Statistical analysis involved triplicate measurements, and TOC removal was calculated to assess mineralization.