1：Experimental Design and Method Selection:

The study involved preparing a ternary composite photocatalyst through chemical reduction and calcination methods to enhance visible-light photocatalytic activity via Z-scheme and heterojunction mechanisms.

2：Sample Selection and Data Sources:

Materials included titanium dioxide, melamine, ferrous sulfate, sodium borohydride, and pollutants (RhB, TC, BH) sourced from Aladdin Industrial Corporation.

3：List of Experimental Equipment and Materials:

Equipment included XRD diffractometer (D/Max-2400), SEM (NOVA NANO SEM 450), TEM (Tecnai F30), UV–vis spectrophotometer (JASCO V-550), XPS (ESCALAB 250Xi), muffle furnace, vacuum oven, ultrasonic bath, centrifuge, and halogen lamp. Materials were as specified in Section

4：Experimental Procedures and Operational Workflow:

Steps included preparation of Fe0/TiO2 by chemical reduction, protonation of g-C3N4 nanosheets, synthesis of g-C3N4/Fe0/TiO2 composite, characterization using various techniques, and photocatalytic degradation experiments under visible light with pH variation and scavenger addition.

5：Data Analysis Methods:

Data were analyzed using UV–vis spectrophotometry for concentration measurements, XRD for crystal structure, SEM/TEM for morphology, XPS for chemical states, and PL/ESR for radical detection; degradation efficiency was calculated as (C0 - C)/C0.