1：Experimental Design and Method Selection:

The study involves designing a Cu2O/Carbon film/NiCoB-GO heterostructure photocathode using electrodeposition for Cu2O, chemical vapor deposition (CVD) for carbon film, and a solution-based method for NiCoB-GO catalyst. Femtosecond transient absorption spectroscopy is used to study carrier dynamics.

2：Sample Selection and Data Sources:

Samples include Cu2O films on FTO glass, carbon-coated Cu2O, and NiCoB-GO catalysts. Data are obtained from characterization techniques like SEM, TEM, XRD, XPS, and electrochemical measurements.

3：List of Experimental Equipment and Materials:

Equipment includes field emission scanning electron microscope (SIRON-100), transmission electron microscope (Tecnai G2 F20 S-TWIN), X-ray photoelectron spectrometer (Escalab 250Xi), X-ray diffractometer (X'Pert PRO), femtosecond transient absorption spectroscopy setup (Yb:KGW laser, NOPA), and potentiostat (Bio-Logic VSP). Materials include FTO glass, copper sulfate, lactic acid, glucose, nickel nitrate, cobalt nitrate, sodium borohydride, graphene oxide, and various chemicals from Sinopharm and other suppliers.

4：Experimental Procedures and Operational Workflow:

Cu2O is electrodeposited on FTO; carbon film is deposited via CVD using glucose; NiCoB-GO is synthesized by reducing metal salts with NaBH4 in the presence of GO and then spin-coated onto Cu2O/C. Characterization and PEC measurements are performed in a three-electrode system with specific electrolytes and light sources.

5：Data Analysis Methods:

Data are analyzed using techniques like EIS for charge transfer resistance, Mott-Schottky plots for flat band potential and carrier density, and transient absorption decay for carrier lifetime. Statistical fitting is applied where necessary.