1：Experimental Design and Method Selection:

The study involved synthesizing 0D/2D heterostructures of oxygen vacancy-rich TiO2 quantum dots confined in g-C3N4 nanosheets via in-situ pyrolysis of NH2-MIL-125 (Ti) and melamine. Charge dynamics were analyzed using time-resolved photoluminescence (tr-PL) and transient absorption (TA) spectra to understand charge transfer mechanisms.

2：Sample Selection and Data Sources:

Samples included pristine g-C3N4, TiO2/g-C3N4 composites, and various TiO2-x/g-C3N4 heterostructures with different mass ratios of Ti-MOF to melamine. Data were sourced from synthesized materials and standard chemical reagents.

3：List of Experimental Equipment and Materials:

Equipment included SEM (Hitachi SU8220), TEM (Tecnai G220 S-twin), XRD (Smart Lab 9), FT-IR (EQUINOX55), XPS (Thermo VG ESCALAB250), nitrogen sorption analyzer (Quantachrome autosorb-iQ2), UV-Vis spectrometer (JASCO V-550), GC/MS (Agilent 5975C), PL spectrometer (JASCO FP-6200), EPR (Bruker A220-9.5/12), UV Raman spectrograph, tr-PL system (PicoQuant PicoHarp 300), femtosecond laser (Mai Tai DeepSee), and photocatalytic setup with Xenon lamp (PLS-SXE300C). Materials included melamine, nitric acid, NH2-BDC, TOPT, DMF, methanol, MeCN, TEOA, bpy, CoCl2, and CO2 gas.

4：5/12), UV Raman spectrograph, tr-PL system (PicoQuant PicoHarp 300), femtosecond laser (Mai Tai DeepSee), and photocatalytic setup with Xenon lamp (PLS-SXE300C). Materials included melamine, nitric acid, NH2-BDC, TOPT, DMF, methanol, MeCN, TEOA, bpy, CoCl2, and CO2 gas. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Synthesis involved thermal polymerization and pyrolysis steps. Characterization included morphological, structural, optical, and electrochemical analyses. Photocatalytic tests were conducted in a quartz vessel under visible light irradiation, with gas products analyzed by GC.

5：Data Analysis Methods:

Data were analyzed using deconvolution/fit programs for tr-PL, multi-exponential decay fitting for TA spectra, and standard software for other instruments. Statistical analysis involved comparing photocatalytic activities and charge dynamics parameters.