Sustainable multifunctional zinc oxide quantum dots-aided double-layers security paper sheets

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Fluorescence is a key anti-counterfeiting technology.
• Zinc oxide quantum dots (ZnOQds) exhibit strong fluorescence under UV light.
• ZnOQds offer sustainable and robust alternatives to organic dyes for security printing.

Purpose of the Study:

• To prepare ZnOQds using a green method.
• To develop and characterize ZnOQds-based hybrid papers for anti-counterfeiting applications.
• To evaluate the stability, mechanical properties, and antimicrobial activity of the developed hybrid papers.

Main Methods:

• Green synthesis of ZnOQds.
• Characterization using UV-visible spectroscopy, Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD).
• Fabrication of double-layer hybrid sheets with varying ZnOQds concentrations (0.5 and 1 wt./v) and characterization via Field Emission Scanning Electron Microscopy (FE-SEM).

Main Results:

• Formation of ZnOQds nanocrystals with an average size of 7.3 nm was confirmed.
• Hybrid sheets demonstrated superior mechanical stability compared to single-layer paper and polymer films.
• Photoluminescence analysis indicated excellent anti-aging properties, projecting over 25 years of stability.
• Broad-spectrum antimicrobial activity was observed in the hybrid sheets.

Conclusions:

• Green-synthesized ZnOQds can be effectively utilized in hybrid papers for advanced anti-counterfeiting.
• The developed hybrid papers possess excellent mechanical and long-term stability.
• The hybrid papers exhibit promising antimicrobial properties, broadening their application potential.