1：Experimental Design and Method Selection:

The study involved fabricating photocatalysts by treating graphitic carbon nitride (g-C3N4) with hydrogen peroxide to activate it (ag-C3N4) and decorating it with carbon dots (CDs) to form binary nanocomposites. The photocatalytic performance was evaluated under visible light irradiation for the degradation of various pollutants (MB, RhB, fuchsine, phenol) and photoreduction of Cr(VI).

2：Sample Selection and Data Sources:

Samples included pristine g-C3N4, ag-C3N4 with different H2O2 concentrations (1M to 4M), and ag-C3N4/CDs nanocomposites with varying CDs volumes (0.25 mL to 1 mL). Pollutants used were MB, RhB, fuchsine, phenol, and Cr(VI) in aqueous solutions.

3：25 mL to 1 mL). Pollutants used were MB, RhB, fuchsine, phenol, and Cr(VI) in aqueous solutions. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a domestic microwave oven (750 W), LED lamp (50 W) as visible light source, spectrophotometer for concentration measurements, centrifuge (7500 rmin-1), oven for drying, sonicator, and various characterization instruments (XRD, EDX, SEM, TEM, HRTEM, XPS, FT-IR, UV-vis DRS, PL, TG, BET surface area analyzer). Materials included melamine (Loba Chemie), hydrogen peroxide (Loba Chemie, wt. 30%), citric acid (Merck, 99%), urea (Merck, 99%), and pollutants like RhB, MB, fuchsine, phenol, and Cr(VI).

4：Experimental Procedures and Operational Workflow:

g-C3N4 was synthesized from melamine by heating. ag-C3N4 was prepared by stirring g-C3N4 in H2O2 solution, washing, and drying. CDs were synthesized from citric acid and urea using microwave irradiation, followed by centrifugation. Nanocomposites were prepared by sonicating ag-C3N4 with CDs in water and drying. Photocatalytic tests involved sonicating photocatalyst in pollutant solution, stirring in dark for equilibrium, irradiating with LED lamp, and sampling at intervals for spectrophotometric analysis. Radical trapping experiments used scavengers like benzoquinone, 2-propanol, and ammonium oxalate.

5：Data Analysis Methods:

Data were analyzed using spectrophotometry for concentration changes, with rate constants calculated for degradation processes. Characterization data were interpreted using standard techniques (e.g., XRD for crystal structure, BET for surface area, PL for charge separation).