1：Experimental Design and Method Selection:

The study involves synthesizing a TiO2@MOF core–shell nanorod array using a layer-by-layer self-assembly method to form a p–n heterojunction. Photoelectrochemical measurements, surface photovoltage spectroscopy, and various characterization techniques are employed to analyze charge separation and injection efficiencies.

2：Sample Selection and Data Sources:

Samples include bare TiO2 nanorod arrays, TiO2@MOF, and TiO2@Co-MOF nanorod arrays grown on fluorine-doped tin oxide (FTO) substrates. Data are obtained from experimental measurements under controlled conditions.

3：List of Experimental Equipment and Materials:

Equipment includes a Gamry Reference 3000 Potentiostat/Galvanostat/ZRA Instrument, JEOL JSM-7600 FESEM, JEOL JEM 2100F TEM, Shimadzu UV-2550 spectrometer, Physical Electronics PHI 5000 Versa Probe XPS, and a 300 W Xe lamp. Materials include TiO2 nanorods, MOF precursors (TCPP, ZrCl4), CoCl2·6H2O, and electrolytes (Na2SO4, TEOA).

4：Experimental Procedures and Operational Workflow:

TiO2 nanorod arrays are grown hydrothermally on FTO, followed by MOF coating via layer-by-layer immersion. Co(III) is introduced by refluxing. Photoelectrochemical tests are conducted in a three-electrode cell with Pt counter and Ag/AgCl reference electrodes under illumination. Characterization involves SEM, TEM, XRD, XPS, UV-Vis, IPCE, M-S plots, and SPV measurements.

5：Data Analysis Methods:

Data are analyzed using equations for photocurrent density, charge injection efficiency, charge separation efficiency, IPCE, capacitance from EIS, and SPV amplitude. Statistical analysis includes comparing enhancements in photocurrent and efficiencies.