1：Experimental Design and Method Selection:

The study involved synthesizing Ni2P/Ni@C/g-C3N4 composites via pyrolysis and phosphidation of Ni-MOF/g-C3N4 precursor to improve charge separation and H2 production efficiency. Theoretical models include band alignment analysis and electron transfer mechanisms.

2：Sample Selection and Data Sources:

Samples included Ni-MOF synthesized solvothermally, g-C3N4 from melamine pyrolysis, and composites annealed at various temperatures (450-600°C). Data were obtained from characterization techniques and photocatalytic tests.

3：List of Experimental Equipment and Materials:

Equipment included Rigaku D–MAX 2500/PC diffractometer for XRD, Thermo Scientific Kα XPS spectrometer, Lambda 750 UV/VIS/NIR spectrometer, TESCAN-VEGA3 SEM, Bruker super-X EDS for STEM-EDS, F-4500 FL fluor-spectrophotometer for PL, Renishaw InVia micro-Raman spectrometer, 300-W Xe lamp for light source, GC-7920 gas chromatography system, CEL-NP2000 optical power meter, CHI 660D electrochemical workstation, IM6e electrochemical station. Materials included Ni-MOF, g-C3N4, NaH2PO2, Eosin Y, triethanolamine, N2 gas.

4：Experimental Procedures and Operational Workflow:

Ni-MOF/g-C3N4 was prepared by self-assembly, annealed under N2 at specified temperatures, then phosphidated with NaH2PO2 at 300°C. Photocatalytic H2 evolution was conducted in a quartz flask with EY sensitizer and TEOA sacrificial agent under visible light, with H2 quantified by GC. Photoelectrochemical measurements involved electrode preparation and analysis using a three-electrode system.

5：Data Analysis Methods:

Data were analyzed using XRD for phase identification, XPS for elemental states, UV-Vis for optical properties, SEM/TEM for morphology, PL for charge transfer, Raman for carbon graphitization, photocurrent and EIS for electrochemical properties, and statistical analysis of H2 evolution rates.