1：Experimental Design and Method Selection:

The study involved synthesizing BiOCl nanoplates via hydrothermal method and BiOCl-Bi2S3 composites via in-situ ion exchange at room temperature using thioacetamide as sulfur source. Photocatalytic performance was evaluated through methylene blue degradation under visible light.

2：Sample Selection and Data Sources:

Bismuth nitrate pentahydrate, mannitol, sodium chloride, and thioacetamide were used as chemicals. Methylene blue was the model pollutant.

3：List of Experimental Equipment and Materials:

X-ray diffractometer (D/max 2550, Rigaku), FT-IR spectrometer (Nicolet 6700), XPS spectrometer (Thermo Escalab 250), SEM (Nova Nano 230, FEI), TEM (JEM-2100F, Japanese electronics), UV-Vis spectrometer (Evolution 220), electrochemical workstation (CHI 660E), Xe lamp (300 W).

4：Experimental Procedures and Operational Workflow:

Synthesis of BiOCl nanoplates at 160°C for 3h, ion exchange with TAA for 4h at room temperature. Photocatalytic tests involved stirring in dark for 2h, then irradiation with sampling every 30min. Photoelectrochemical measurements used a three-electrode system.

5：Data Analysis Methods:

XRD for phase identification, FT-IR and XPS for chemical analysis, SEM/TEM for morphology, UV-Vis for optical properties, pseudo-first-order kinetics for degradation rates, EIS and photocurrent for carrier separation analysis.