1：Experimental Design and Method Selection:

A facile one-step hydrothermal method was used to synthesize RGO-M-MoS2 composites with metal ions (Fe3+, Co2+, Ni2+, Cu2+, Zn2+) as bridges. The method involves preparing GO, decorating it with metal ions, and then growing MoS2 nanolayers vertically on RGO.

2：Sample Selection and Data Sources:

Graphite powder was used to synthesize GO. Metal chlorides (FeCl3, CoCl2, NiCl2, CuCl2, ZnCl2), ammonium molybdate tetrahydrate, and thiourea were used as precursors. Distilled water was the solvent.

3：List of Experimental Equipment and Materials:

Equipment includes ultrasonic vibrator, Teflon-lined autoclave, freeze-dryer, UV-2600 spectrophotometer, Nicolet 6700 FTIR spectrometer, Thermo Nicolet Nexus 670 Raman spectrometer, Hitachi SEM, JEOL JEM-2010F TEM, Micrometrics ASAP 2020 adsorption analyzer, X'Pert PRO diffractometer, Thermo ESCALAB 250 XPS spectrometer, CH Instruments 660E electrochemical workstation, 150 W Xenon arc lamp. Materials include graphite, H2SO4, NaNO3, KMnO4, H2O2, HCl, ethanol, isopropyl alcohol, Nafion solution, Ag/AgCl electrode, Pt wire, glassy carbon electrodes.

4：Experimental Procedures and Operational Workflow:

GO was synthesized from graphite using Hummers' method. GO was dispersed in water, metal chlorides were added and stirred to form GO-M composites. Molybdate precursor and thiourea were added, and the mixture was hydrothermally treated at 180°C for 18 hours. Products were washed, centrifuged, and freeze-dried. Electrodes were prepared by mixing catalyst powder with water, isopropyl alcohol, and Nafion, then coating on GCE. Electrochemical measurements (LSV, CV, EIS, chronoamperometry) were performed in 0.5 M H2SO4 with a three-electrode setup under dark and light conditions.

5：5 M H2SO4 with a three-electrode setup under dark and light conditions. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using DFT calculations with Quantum-Espresso package, PBE functional, and plane wave basis sets. Electrochemical data were fitted to Tafel equation, and EIS data were fitted to Randle's equivalent circuit. Statistical analysis included calculating exchange current densities and charge transfer resistances.