1：Experimental Design and Method Selection:

Cu3SnS4 nanoparticles were synthesized by solvothermal method using different solvents (deionized water, N,N-dimethylformamide, and poly ethylene glycol). The structural, morphological, and optical properties were characterized using XRD, SEM, EDX, HR-TEM, BET, UV-Vis-NIR, and PL spectroscopy. Electrocatalytic and photocatalytic activities were evaluated through linear sweep voltammetry, Tafel plots, electrochemical impedance spectroscopy, and photocatalytic degradation of methylene blue under visible light.

2：Sample Selection and Data Sources:

Samples were prepared with stoichiometric ratios of starting materials, maintaining the same reaction temperature and time for all solvents.

3：List of Experimental Equipment and Materials:

X-ray diffractometer (Shimadzu XRD-6000), SEM (JEOL 6390), EDX, HR-TEM (JEOL JEM 2100), BET analyzer (Microtrac BEL, BELSORP-Max), UV-Vis-NIR spectrometer (JASCO V-770), PL spectrophotometer (FLUOROLOG, HORIBA JobinYvon), CHI 660D electrochemical workstation.

4：Experimental Procedures and Operational Workflow:

Synthesis involved dissolving precursors in solvents, transferring to an autoclave, heating, washing, and drying. Characterization followed standard procedures for each technique. Electrochemical and photocatalytic tests were conducted under controlled conditions.

5：Data Analysis Methods:

XRD patterns analyzed for crystal structure, SEM and TEM for morphology, EDX for composition, BET for surface area, UV-Vis-NIR for optical properties, PL for charge carrier recombination, LSV and Tafel plots for electrocatalytic activity, and photocatalytic degradation rates for photocatalytic activity.