1：Experimental Design and Method Selection:

A metal chloride-involved etching method was devised to partially etch Bi2O2CO3, forming heterojunctions and enabling cation doping simultaneously. This method aimed to improve light absorption and charge carrier separation.

2：Sample Selection and Data Sources:

Pure Bi2O2CO3 (BOC) was synthesized hydrothermally. Partially etched samples were prepared using stannous chloride (SnCl2) or hydrochloric acid (HCl) under solvothermal conditions. Pollutants used were RhB, TC, and BPA.

3：List of Experimental Equipment and Materials:

Equipment included Teflon-lined autoclave, magnetic stirrer, centrifuge, XRD diffractometer (Shimadzu XRD-6000), SEM (JEOL JSM-7001F), TEM (Tecnai G2 F30 S-TWIN), FT-IR spectrophotometer (Nexus 470), Raman spectroscope (Renishaw Invia), XPS (VG MultiLab 2000), surface area analyzer (TriStar II 3020), UV-vis spectrometer (Shimadzu UV-2450), PL spectrometer (Varian Cary Eclipse), ESR spectrometer (Bruker JES-FA200), electrochemical workstation (CHI 660E), and light sources (300 W Xenon lamp, 250 W high-pressure mercury lamp). Materials included various chemicals from Sinopharm Chemical Reagent Co. Ltd, Aladdin, Macklin, Sigma-Aldrich, Shanghai Chengjie Chemical Co. Ltd, and Zhenjiang Zhongpu Steel Materials Co. Ltd.

4：Experimental Procedures and Operational Workflow:

Synthesis involved dissolving precursors, hydrothermal/solvothermal reactions, centrifugation, washing, and drying. Photocatalytic tests involved stirring pollutant solutions with catalysts under light irradiation, sampling at intervals, and analyzing degradation.

5：Data Analysis Methods:

Degradation efficiency was measured using UV-vis spectroscopy. Kinetic analysis, TOC measurements, scavenger experiments, ESR, and electrochemical analyses (photocurrent, EIS, RDE) were performed to study ROS generation and mechanisms.