1：Experimental Design and Method Selection:

The study involved synthesizing a mixture of GQD-1 from graphite using oxidative exfoliation and subsequent chemical modification, followed by separation using size-exclusion chromatography to isolate different-sized GQDs (GQD-1 a and GQD-1 b). Theoretical models included DFT calculations for band gap analysis.

2：Sample Selection and Data Sources:

Commercially available graphite was used as the starting material. GQD-2 was prepared from graphite, and GQD-1 was synthesized by reacting with p-methoxybenzylamine.

3：List of Experimental Equipment and Materials:

Equipment included chromatography columns (BioBeads S-X1, Shodex GPC columns), spectrometers (VARIAN NMR, JASCO FT/IR, UV/Vis, emission), TEM (JEM-2010), XPS (Shimazu ESCA-3400), DLS (Malvern zetasizer nanoZS), CV analyzer (ALS/HCH Instruments), and time-resolved emission spectrophotometer (HORIBA DeltaFlex). Materials included chemicals from Kanto Chemical, Wako Pure Chemical, Tokyo Kasei Kogyo, Sigma-Aldrich, and solvents like THF, chloroform.

4：Experimental Procedures and Operational Workflow:

Graphite was oxidatively cut with nitric and sulfuric acids to produce GQD-2, which was then treated with oxalyl chloride and p-methoxybenzylamine to form the mixture of GQD-1. This mixture was purified using BioBeads S-X1 and separated via preparative GPC with Shodex columns. Fractions were analyzed using DLS, TEM, IR, NMR, XPS, UV/Vis, PL, CV, and lifetime measurements.

5：This mixture was purified using BioBeads S-X1 and separated via preparative GPC with Shodex columns. Fractions were analyzed using DLS, TEM, IR, NMR, XPS, UV/Vis, PL, CV, and lifetime measurements. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using fitting functions for lifetime decays, DFT calculations at the M06-2X/6-31G(d,p) level for band gaps, and standard spectroscopic techniques for characterization.