1：Experimental Design and Method Selection:

A three-step synthesis process was employed: hydrothermal method for growing ZnO nanorods, chemical bath deposition for depositing CdS quantum dots, and successive ionic layer adsorption and reaction (SILAR) for depositing PbS quantum dots and forming top-opened nanotubes. This design aims to create multi-heterojunctions and enhance surface area for improved photoelectrochemical performance.

2：Sample Selection and Data Sources:

Samples included ZnO nanorods, ZnO/CdS nanotubes with varying deposition times (20-60 min), and ZnO/CdS/PbS nanotubes with varying SILAR cycles (2-8 times). Data were obtained from characterization techniques and photoelectrochemical measurements.

3：List of Experimental Equipment and Materials:

Equipment included X-ray diffractometer (Rigaku D/max 2500 v/pc), field-emission scanning electron microscope (FEI Quanta 200 FEG), transmission electron microscope (JEM-2100 JEOL), photoluminescence spectrophotometer (RF-5301PC), ultraviolet-visible spectrophotometer (SHIMADZU UV-2550), X-ray photoelectron spectrometer (Escalab 250Xi), incident photon-to-current conversion efficiency measurement system (Keithley 2000 m with DK240 monochromator), inductively coupled plasma atomic emission spectrometer (Perkin-Elmer Plasma 400), and electrochemical workstation (CHI 660E). Materials included FTO glass, C4H10O6Zn, ethanol, C6H12N4, Zn(NO3)2, Cd(NO3)2, thioacetamide, Pb(NO3)2, Na2S, Na2SO3, and other analytical grade reagents.

4：Experimental Procedures and Operational Workflow:

ZnO nanorods were grown on FTO via hydrothermal method. CdS was deposited by chemical bath deposition at 40°C for 20-60 min. PbS was deposited by SILAR cycles (2-8 times). Characterization involved XRD, FESEM, TEM, PL, UV-Vis, XPS, IPCE, and ICP-AES. Photoelectrochemical measurements were done in a three-electrode system with visible light irradiation (100 mW cm-2 from a 300W xenon lamp with 400 nm cutoff filter), using Na2S/Na2SO3 electrolyte.

5：Data Analysis Methods:

Data were analyzed using standard techniques for each instrument, including peak identification in XRD and XPS, absorption spectra analysis, photocurrent density calculations, and hydrogen evolution rate measurements. Statistical analysis was not explicitly mentioned.