1：Experimental Design and Method Selection:

The study synthesized fluorine surface modified mpg-C3N4 photocatalysts using a hard template method at room temperature by controlling pH. The mechanism involved etching SiO2 with NH4HF2 and electrostatic binding of F- ions under acidic conditions. Theoretical models included DFT calculations for band structure analysis.

2：Sample Selection and Data Sources:

Samples were prepared from melamine and silica sol, with variations in pH during washing (2.5, 4.3, 5.1, 7.0) to produce mCN-2.5, mCN-4.3, mCN-5.1, and CN. Data sources included characterization techniques and photocatalytic degradation tests using Rhodamine B (RhB).

3：5, 3, 1, 0) to produce mCN-5, mCN-3, mCN-1, and CN. Data sources included characterization techniques and photocatalytic degradation tests using Rhodamine B (RhB). List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included XRD (D/MAX-2200/PC, Rigaku), XPS (Kratos Analytical Ltd., XSAM800), TEM (Tecnai G2F20 S-TWIN, FEI), FT-IR (VERTE70, Bruker), BET surface area analyzer (Model BET 3H-2000 BET-A, Beishide Instrumentation Technologies Ltd.), zeta potential analyzer (NANO-ZS, Malvern), fluorescence spectrophotometer (FS5, Edinburgh), HPLC (Waters E2695), photochemical reactor (XPA-7 type, Xujiang Machine Factory), UV-Vis spectrophotometer (SP-756P), and electrochemical workstation (CHI600). Materials included melamine, silica sol, NH4HF2, NaOH, ethyl alcohol, RhB, benzoquinone (BQ), ethylene diaminetetraacetic acid (EDTA), tert-butyl alcohol (TBA), Na2SO4, and FTO substrates.

4：0). Materials included melamine, silica sol, NH4HF2, NaOH, ethyl alcohol, RhB, benzoquinone (BQ), ethylene diaminetetraacetic acid (EDTA), tert-butyl alcohol (TBA), Na2SO4, and FTO substrates. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Synthesis involved dissolving melamine in silica sol at 90°C, calcining at 550°C for 4 h, etching with NH4HF2, washing with NaOH at varying pH, and drying. Characterization included XRD, XPS, TEM, FT-IR, BET, zeta potential, PL, carrier lifetime, and HPLC. Photocatalytic activity was measured by degrading RhB under UV light, with scavenger tests using BQ, EDTA, and TBA. Photoelectrochemical properties were assessed using a three-electrode system with Ag/AgCl reference and FTO working electrodes under Xe lamp irradiation.

5：Data Analysis Methods:

Data analysis involved Rietveld refinement for XRD, peak fitting for XPS, BET calculations for surface area, kinetic modeling for degradation rates, DFT for band structures, and two-exponential fitting for carrier lifetime.