1：Experimental Design and Method Selection:

A facile one-step solvothermal method was used to synthesize amphipathic carbon dots from p-Phenylenediamine and urea in DMSO with PEG. Absorption, steady-state, and time-resolved spectroscopy were employed to study optical properties and solvent effects.

2：Sample Selection and Data Sources:

The CDs were synthesized and characterized. Various solvents (toluene, acetone, DMSO, ethanol, water) and metal ions (Ag+, Cd2+, Cs2+, Cu2+, Fe2+, Fe3+, In3+, K+, Mg2+, Mn2+, Na+, Pb2+, Zn2+) were used for testing.

3：List of Experimental Equipment and Materials:

Materials included p-Phenylenediamine, urea, DMSO, PEG, solvents, and metal salts. Equipment included HRTEM (JEM-2100F, JEOL), XRD (D8 Advance, Bruker), XPS (ESCALAB 250XI, Thermo), FT-IR (Nicolet 6700, ThermoFisher), fluorescence spectrophotometer (F97XP, Shanghai Lengguang), UV-vis spectrophotometer (759S, Shanghai Lengguang), time-resolved spectrofluorometer (FLS 920, Edinburgh Instruments).

4：Experimental Procedures and Operational Workflow:

Synthesis involved heating the mixture at 180°C for 6 hours, followed by precipitation, centrifugation, and drying. Characterization included TEM, XRD, XPS, FT-IR, absorption and PL measurements, lifetime measurements, and QY calculations. Ion sensing involved adding metal ions to CDs solution and measuring PL spectra.

5：Data Analysis Methods:

Data were analyzed using standard methods for spectroscopy, including fitting decay curves, calculating QY with quinine sulfate as standard, and applying Stern-Volmer equation for quenching analysis.