1：Experimental Design and Method Selection:

Chemical co-precipitation method was used for synthesis, with thioglycolic acid as a capping agent to control size. Various characterization techniques (XRD, UV-Vis, Raman, FESEM, FTIR) were employed to evaluate properties. Photocatalytic and catalytic activities were tested under visible light and with NaBH

2：Sample Selection and Data Sources:

Nanoparticles of pristine CdS and Fe-doped CdS (5%, 10%, 15%) were synthesized. Methylene blue dye solution (10 mg/L) was used for degradation tests.

3：List of Experimental Equipment and Materials:

Cadmium chloride 2,5 hydrate, sodium sulfide pentahydrate, thioglycolic acid, iron(III) nitrate 9-hydrate, deionized water, mercury lamp (400 W), UV-Vis spectrophotometer, XRD (PANalytical Xpert PRO), FTIR (Perkin Elmer spectrometer), Raman spectrometer (DXR Raman microscope, Thermo Scientific), FESEM (JSM-6460LV), EDX spectrometer, UV-Visible Genesys 10S spectrophotometer.

4：Experimental Procedures and Operational Workflow:

Synthesis involved preparing solutions, adding TGA and Na2S dropwise, centrifuging, washing, drying. Photocatalytic activity was tested by mixing dye with catalyst, illuminating with visible light, and measuring absorption at intervals. Catalytic reduction used NaBH4 and catalyst, monitoring decolorization.

5：Data Analysis Methods:

Crystallite size calculated using Debye-Scherrer formula from XRD data. Band gap determined from UV-Vis spectra using Tauc plot. Degradation efficiency calculated from absorption intensity changes.