Carbon dot-loaded Fe₃O₄as photonic pigments for multilevel anti-counterfeiting

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Amorphous colloidal arrays (ACAs) from microspheres yield angle-independent structural colors.
• Modifying constituent microspheres can impart additional functionalities.
• Carbon quantum dots (CDs) offer unique optical properties.

Purpose of the Study:

• To fabricate Fe3O4@SiO2/SiCDs nanospheres with core-shell structures.
• To construct ACAs using these nanospheres for multidimensional information display.
• To explore their potential in anti-counterfeiting, bioimaging, and sensing.

Main Methods:

• Silane-functionalized carbon quantum dots (SiCDs) were incorporated into the Stöber reaction to create Fe3O4@SiO2/SiCDs nanospheres.
• Amorphous colloidal arrays (ACAs) were assembled on printing paper via simple permeation using these nanospheres.
• The thickness of the SiO2/SiCDs composite layer was adjusted to tune properties.

Main Results:

• The fabricated ACAs exhibited angle-independent structural colors and fluorescence under UV light.
• The nanospheres displayed magnetic properties due to the Fe3O4 core.
• Digital patterns showed excellent multi-level anti-counterfeiting characteristics, even when exposed to water.

Conclusions:

• Fe3O4@SiO2/SiCDs nanospheres enable the creation of multifunctional materials with tunable optical and magnetic properties.
• These materials are suitable for multidimensional information display under varying conditions.
• Potential applications include advanced anti-counterfeiting pigments, bioimaging, and sensing displays.