Development of fluorescent carbon dots ink from rice straw waste toward security authentication

Abstract

New photochromic emissive nitrogen-doped carbon dots (N-CDs) nanocomposite ink was prepared for anticounterfeiting digital printing. We developed a simple, green and effective approach to reuse rice straw waste as a precursor for the preparation of fluorescent N-CDs via one-pot hydro-thermal carbonization in an aquatic medium using NH4OH as a cheap passivating substance. N-doped carbon dots displayed QY (quantum yield) up to 22.51% with an excitation of 356 nm and fluorescence maxima at 452 nm. The photochromic emissive nitrogen-doped carbon dots nanocomposite ink was digitally printed onto cellulose sheets demonstrating a colorless appearance with a capability to change color to blue emission underneath UV as verified by CIE Lab. N-CDs was prepared in the nanoparticle form and studied by transmission electron microscope (TEM) and infrared spectroscopy (FT-IR). The morphologies of the printed sheets were studied by energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and FT-IR. Under ultraviolet and visible lights, the printed sheets showed an effective reversible fluorescence photochromism without fatigue. The rheological performance of the prepared N-CDs nanocomposite ink was explored. The mechanical behavior of the printed sheets was also investigated.