1：Experimental Design and Method Selection:

The study utilized amine-terminated silicon nanocrystals (Si NCs) synthesized via a chemical reduction method, with luminescence quenching as the transduction mechanism for Fe3+ detection. Photoluminescence spectroscopy and time-resolved measurements were employed to investigate the quenching mechanism and selectivity.

2：Sample Selection and Data Sources:

Si NCs were synthesized and characterized; aqueous solutions of various metal ions (Fe3+, Fe2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+) at concentrations up to 900 × 10?6 m were used as analytes.

3：List of Experimental Equipment and Materials:

Equipment includes transmission electron microscope (JEOL 2100), X-ray photoelectron spectrometer (Kratos Ultra DLD), IR spectrometer (Perkin Elmer Two), UV–vis spectrophotometer (Shimadzu UV PC-2401), photoluminescence spectrophotometer (Agilent Cary Eclipse), confocal fluorescence microscope (MicroTime 200, PicoQuant GmbH). Materials include tetraoctylammonium bromide, SiCl4, lithium tri-sec-butylborohydride, allylamine, various metal salts (e.g., Fe(NO3)3·9H2O), deionized water, and chromatography columns with Sephadex gel LH-

4：Experimental Procedures and Operational Workflow:

Si NCs were synthesized in an inert atmosphere, functionalized with allylamine, purified, and dispersed in water. For sensing, Si NC dispersions were mixed with analyte solutions, and PL spectra were recorded after equilibration. Time-resolved PL measurements were conducted to study lifetimes.

5：Data Analysis Methods:

Data were analyzed using Stern–Volmer plots for quenching constants, linear regression for detection limits, and multi-exponential fitting for lifetime analysis using software like FluoFit 4.2.