1：Experimental Design and Method Selection:

The study designed a multi-interface n-p-n double heterojunction structure (BiSI/MoS2/CdS) using hydrothermal and solvothermal methods to enhance photocatalytic hydrogen evolution. Theoretical models included band structure analysis and carrier dynamics optimization.

2：Sample Selection and Data Sources:

Samples included BiSI, MoS2, CdS, and their composites (BiSI/MoS2, MoS2/CdS, BiSI/MoS2/CdS), synthesized from reagent-grade chemicals like bismuth nitrate, thioacetamide, sodium iodide, sodium molybdate, cadmium chloride, and sodium thiosulfate.

3：List of Experimental Equipment and Materials:

Equipment: X-ray diffraction (XRD; Empyeran), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM; Hitachi S-4800), Quantachrome instrument for pore properties, spectrophotometer (UV-3600), fluorometer (F-7000, Hitachi), electrochemical workstation (CHI660E, Shanghai Chenhua Instruments), photocatalytic hydrogen evolution system (Perfectlight Labsolution), 300 W Xenon light with UV filter, online gas chromatograph (SHIMADZU GC-2014). Materials: Chemicals as listed, with deionized water and electrolytes like Na2SO4 solution.

4：4). Materials:

4. Experimental Procedures and Operational Workflow: Synthesis involved sequential steps: BiSI synthesis by stirring Bi(NO3)3·5H2O in CH3COOH, adding thioacetamide and NaI, heating at 180°C; BiSI/MoS2 synthesis by dispersing BiSI, adding Na2MoO4 and thioacetamide, heating at 160°C; BiSI/MoS2/CdS synthesis by adding CdCl2 and Na2S2O3, heating at 100°C. Characterization included XRD, XPS, SEM, BET, UV-Vis, PL, Mott-Schottky, EIS, and photocurrent tests. Photocatalytic tests used 50 mg catalyst in 0.1 L solution with 10% lactic acid, under visible light (λ>420 nm), with hydrogen measured by GC.

5：Experimental Procedures and Operational Workflow:

5. Data Analysis Methods: Data analyzed using Kubelka-Munk simulation for band gaps, Mott-Schottky theory for flat band potentials, EIS for charge transfer resistance, and statistical analysis of hydrogen production rates. Software tools included standard instrument software for data processing.