1：Experimental Design and Method Selection:

The study involved synthesizing undoped and doped ZnO QDs (Al-doped and In-doped) using a wet-chemical method, characterizing their structural, morphological, and optical properties, and evaluating their gas sensing performance towards acetylene.

2：Sample Selection and Data Sources:

The samples included undoped ZnO QDs, Al-doped ZnO QDs, and In-doped ZnO QDs. Characterization techniques included TEM, XRD, FTIR, XPS, UV–vis spectroscopy, and N2 adsorption–desorption isotherm analysis.

3：List of Experimental Equipment and Materials:

Equipment used included a transmission electron microscope (TEM, JEOL JEM ARM 200 F), X-ray diffractometer (XRD, Ultima IV/ME 200DX, Rigaku), FTIR spectrometer (Perkin-Elmer?), XPS (K-alpha Thermo VG), and UV–vis spectrometer (V650 JASCO). Materials included zinc acetate dihydrate, N, N-Dimethylmethanamide, tetramethylammonium hydroxide, Al precursor (Al(O2CCH3)3), and In precursor (InCl3).

4：3). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The synthesis of ZnO QDs involved dissolving zinc acetate dihydrate in DMF, mixing with TMAH solution, centrifuging, and cleaning with acetone. Doped QDs were synthesized by adding Al or In precursors. Sensor devices were fabricated by patterning interdigitated Pt electrodes on SiO2 or Al2O3 substrates, dropping the QD solution, drying, and annealing. Gas sensing measurements were performed in a chamber with mass flow controllers, using a nanovoltmeter and current source.

5：Data Analysis Methods:

The sensing response was calculated as ΔR/Rg, where ΔR = (Ra – Rg). The optical band gap energy was determined using the Tauc relation from UV–vis spectra.