1：Experimental Design and Method Selection:

The study involves synthesizing g-CN films via solvothermal process and calcination, followed by decorating with NiCo-LDH through cathodic electrochemical deposition to act as a co-catalyst for PEC water oxidation.

2：Sample Selection and Data Sources:

FTO substrates are used as the base for film synthesis; samples include bare g-CN and g-CN/LDH composites with varying LDH loading amounts (5, 10, 15, 30 mC).

3：List of Experimental Equipment and Materials:

Equipment includes autoclave for solvothermal synthesis, electrochemical workstation (CHI660A) for deposition and PEC measurements, XRD diffractometer (Bruker D8 advance), XPS spectrometer (ESCALab220i-XL), SEM (Hitachi FE-SEM S4800), UV-vis spectrophotometer (Shimadzu UV-3600), and EIS analyzer (Zahner IM6). Materials include cyanuric chloride, melamine, acetonitrile, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Na2SO4 electrolyte, and FTO substrates.

4：6). Materials include cyanuric chloride, melamine, acetonitrile, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Na2SO4 electrolyte, and FTO substrates. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: g-CN films are synthesized by dispersing precursors in acetonitrile, solvothermal treatment at 180°C for 24h, rinsing, and calcination at 520°C under N

5：NiCo-LDH is deposited electrochemically at -1 V vs. SCE with specified electric quantities. PEC measurements involve LSV, i-t curves, and EIS under illumination with a xenon lamp and 420 nm filter. Data Analysis Methods:

Performance is evaluated through photocurrent densities and EIS Nyquist plots to assess charge transfer resistance; characterization data from XRD, XPS, SEM, EDX, and UV-vis are analyzed to confirm material properties and composition.