Fig. 1. (a) TGA-CdS QDs powder; (b) TGA-CdS QDs solution; (c) UV-excited TGA-CdS QDs solution

Fig. 2. (a) UV absorption spectrum of TGA-CdS QDs; (b) Fluorescence spectrum of TGA-CdS QDs;(c) UV absorption spectrum of TGA-CdS QDs recovery liquid; (d) Fluorescence spectrum of TGA-CdS QDs recovery liquid

Fig. 3. (a) FTIR spectra of PVAc, TGA-CdS QDs, and TGA-CdS QDs/PVAc; (b) XRD patterns of PVAc, TGA-CdS QDs, and TGA-CdS QDs/PVAc

Fig. 4. SEM images: (a) TGA-CdS QDs/PVAc gel fingerprint film; (b) TGA-CdS QDs particles

Fig. 5. (a) 10% PVAc gel fingerprint film; (b) membrane after fingerprint collection; (c) fingerprint display under ultraviolet excitation

Fig. 6. Different mass fractions of PVAc gel fingerprint films were fluorescently displayed under 365 nm UV: (a) 10%; (b) 20%; (c) 30%

Fig. 7. TGA-CdS QDs solutions of different concentrations: (a) 2 mg/mL; (b) 4 mg/mL; (c) 6 mg/mL; (d) 8 mg/mL; (e) 10 mg/mL

Fig. 8. Fingerprint appeared under 365 nm UV: (a) pH=3; (b) pH=5; (c) pH=7; (d) pH=9; (e) pH=11

Fig. 9. (a) Fingerprints taken; (b) fingerprints in TGA-CdS QDs solution; fluorescence of fingerprints at different temperatures: (c) 0 ℃, (d) 25 ℃, (e) 40 ℃; (f) fingerprint in the rinsed image (e)

Fig. 10. Fluorescent fingerprint magnification: (a) scar or fault; (b) bifurcation; (c) lake; (d) cross; (e) suspend;（f）nucleus

Fig. 11. Binding mechanism of TGA-CdS QDs with fingerprint residue