1：Experimental Design and Method Selection:

A facile hydrothermal method was used to synthesize MnxCd1?xS solid solutions and MoS2-modified composites. The one-pot hydrothermal process was employed for MoS2 modification to ensure intimate interfacial contact.

2：Sample Selection and Data Sources:

Samples were prepared with varying x values (0 to

3：0) for MnxCd1?xS and MoS2-loading contents (1 to 0 wt%). Data were obtained from material characterization and photocatalytic activity tests. List of Experimental Equipment and Materials:

Equipment includes autoclave, vacuum oven, XRD (Rigaku Miniflex 600), FESEM (Zeiss-Sigma), HRTEM (JEM2100(HR)), XPS (Thermo Fisher ESCALAB 250Xi), DRS (Shimadzu MPC-3100), PL (Hitachi F-6800), XRF (Bruker S4 Pioneer), electrochemical analyzer (CHI model 618C), gas chromatograph (SP6980). Materials include Cd(Ac)2·4H2O, Mn(Ac)2·2H2O, L-cystine, Na2MoO4·2H2O, NaOH, Na2S, Na2SO3, H2PtCl6, methanol, Nafion, FTO glass, etc.

4：0). Materials include Cd(Ac)2·4H2O, Mn(Ac)2·2H2O, L-cystine, Na2MoO4·2H2O, NaOH, Na2S, Na2SO3, H2PtCl6, methanol, Nafion, FTO glass, etc. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Hydrothermal synthesis at 130°C for 10 h, pH adjustment to

5：0, washing and drying. Photocatalytic tests in a sealed reactor with sacrificial reagents under visible light irradiation. Characterization involved XRD, SEM, TEM, XPS, DRS, PL, XRF, photocurrent, EIS, and Mott-Schottky measurements. Data Analysis Methods:

Data were analyzed using standard techniques for XRD peak identification, bandgap calculation from DRS, PL intensity comparison, electrochemical measurements, and AQY calculation.