1：Experimental Design and Method Selection:

A solution-based synthesis strategy using oleylamine and dodecanethiol as precursors to prepare CuFeSe2 quantum dots (QDs) and nanoparticles, avoiding high-temperature solid-state methods.

2：Sample Selection and Data Sources:

CuFeSe2 nanocrystals synthesized from iron chloride tetrahydrate, cupric chloride dihydrate, selenium powder, oleylamine, and dodecanethiol.

3：List of Experimental Equipment and Materials:

Equipment includes Hitachi-4600 spectrophotometer, Shimadzu UV-2700 spectrophotometer, Japan Science Ultima IV X-Ray Powder Diffractometer, JEOL JEM-2100HR transmission electron microscope, Malvern Instrument particle size analyzer, vibrating sample magnetometer (VSM, BHV-50HTI), Edinburgh FLS-920 fluorescence spectrometer, Phenom Pro X Desktop Scanning Electron Microscope. Materials include FeCl2·4H2O, CuCl2·H2O, Se powder, oleylamine, dodecanethiol, ethanol.

4：Experimental Procedures and Operational Workflow:

Synthesis involves heating precursors in oleylamine and dodecanethiol under nitrogen, injection of solutions, centrifugation, washing, and drying. Characterization includes photoluminescence, UV-vis, XRD, TEM, DLS, VSM, fluorescence lifetime, and EDS measurements. Sensing experiments involve adding Cr2O7 2- ions and measuring fluorescence changes.

5：Data Analysis Methods:

Linear regression for calibration curves, monoexponential fit for lifetime decay, and statistical analysis for recovery and RSD.