1：Experimental Design and Method Selection:

The study involved synthesizing snowflake-like Cu2S/Zn0.5Cd0.5S heterojunction photocatalysts using hydrothermal and calcination methods to form a p–n heterojunction for improved charge separation and photocatalytic hydrogen production under visible light.

2：5Cd5S heterojunction photocatalysts using hydrothermal and calcination methods to form a p–n heterojunction for improved charge separation and photocatalytic hydrogen production under visible light. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Samples included pure Cu2S, pure Zn0.5Cd0.5S, and composites with varying Cu2S content (1-10 wt%), synthesized from chemical precursors like Zn(NO3)2·6H2O, Cd(NO3)2·4H2O, thioacetamide, CuCl2·2H2O, ethylenediamine, and thiourea.

3：5Cd5S, and composites with varying Cu2S content (1-10 wt%), synthesized from chemical precursors like Zn(NO3)2·6H2O, Cd(NO3)2·4H2O, thioacetamide, CuCl2·2H2O, ethylenediamine, and thiourea. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included autoclaves for hydrothermal synthesis, vacuum distillation setup, agate mortar for grinding, D8 Advance diffractometer (XRD), Gemini SEM with EDX, JEM-2100 TEM, UV-3600 spectrophotometer (DRS), FLS 920 spectrometer (PL), ESCALAB250 XPS, Micromeritics ASAP2020 (BET), IM6 electrochemical workstation, photocatalytic activity evaluation system (CEL-SPH2N-D9), 300 W Xe lamp (CEL-HXF300H5), and GC-7900 gas chromatograph. Materials included ethanol, deionized water, Na2S, Na2SO3, and various chemical precursors.

4：Experimental Procedures and Operational Workflow:

Zn0.5Cd0.5S was synthesized hydrothermally at 160°C for 24h; Cu2S was synthesized hydrothermally at 80°C for 8h; composites were prepared by mixing and calcining at 100°C for 1h. Characterization involved XRD, SEM, TEM, EDX, DRS, PL, XPS, BET, photoelectrochemical measurements, and photocatalytic H2 evolution tests under visible light with sacrificial agents.

5：5Cd5S was synthesized hydrothermally at 160°C for 24h; Cu2S was synthesized hydrothermally at 80°C for 8h; composites were prepared by mixing and calcining at 100°C for 1h. Characterization involved XRD, SEM, TEM, EDX, DRS, PL, XPS, BET, photoelectrochemical measurements, and photocatalytic H2 evolution tests under visible light with sacrificial agents. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using XRD for phase identification, SEM/TEM for morphology, EDX for elemental composition, DRS for optical properties, PL for charge separation, XPS for chemical states, BET for surface area, electrochemical measurements for charge transfer, and GC for H2 quantification. AQE was calculated based on light intensity and evolved H2.