1：Experimental Design and Method Selection:

The NiS nanoparticles were synthesized using a chemical displacement method with CTAB as a stabilizer, thioacetamide as the sulfide source, and nickel nitrate as the metal salt. The mixture was refluxed at 65°C for 2 hours, followed by calcination at 600°C for 2 hours to obtain crystalline nanoparticles.

2：Sample Selection and Data Sources:

Analytical grade reagents including nickel nitrate, thioacetamide, CTAB, and methanol were used. All reactions were performed with double distilled water.

3：List of Experimental Equipment and Materials:

Equipment includes UV–1800 Shimadzu spectrophotometer for UV-Vis and photocatalytic measurements, Bruker ALPHA-T FTIR spectrometer, Rigaku D/max 40 kV diffractometer for XRD, JSM-7600F FEG-SEM with EDS, Tecnai G2-F30 HR-TEM, and a muffle furnace for calcination. Materials include nickel nitrate, thioacetamide, CTAB, methanol, and double distilled water.

4：Experimental Procedures and Operational Workflow:

Dissolve nickel nitrate in water, add a mixture of thioacetamide and CTAB in methanol dropwise, reflux at 65°C for 2 hours, cool, centrifuge, wash with water, calcine at 600°C for 2 hours. Characterize using UV-Vis, FTIR, XRD, FEG-SEM, EDS, HR-TEM. For photocatalytic activity, use natural sunlight with Rose Bengal dye solution and NiS nanoparticles, sample every 15 minutes, measure UV-Vis absorption.

5：Data Analysis Methods:

Use Scherrer equation for particle size calculation from XRD data. Use pseudo first-order kinetic model for photocatalytic degradation analysis.