1：Experimental Design and Method Selection

Nb2C QDs were synthesized through a pulsed ultrasound assisted chemical exfoliation in tetrapropylammonium hydroxide (TPAOH). The methodology involved the use of ultrasound to assist in the exfoliation and fragmentation of Nb2C stacks into quantum dots.

2：Sample Selection and Data Sources

Nb2AlC powders were used as the starting material. The synthesis process involved etching the Al element from Nb2AlC using HF solution, followed by exfoliation in TPAOH under ultrasound treatment.

3：List of Experimental Equipment and Materials

Materials included Nb2AlC powders, HF solution, TPAOH, and various chemicals for characterization and testing. Equipment included an atomic force microscope (AFM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectrometer, Raman spectrometer, X-ray photoelectron spectrometer (XPS), X-ray diffractometer (XRD), UV-Vis spectrometer, fluorescence spectrometer, and confocal laser scanning microscope (CLSM).

4：Experimental Procedures and Operational Workflow

The synthesis involved etching Nb2AlC in HF, washing, exfoliation in TPAOH under ultrasound, dialysis to remove residual TPAOH, and freeze-drying to obtain Nb2C QDs. Characterization included AFM, TEM, FTIR, Raman, XPS, XRD, UV-Vis, and fluorescence spectroscopy.

5：Data Analysis Methods

Data analysis involved measuring fluorescence intensity, UV-Vis absorption, particle size distribution, and ζ-potential. Fluorescence lifetime was measured using a time-resolved fluorescence spectrometer.