Abstract
•Fluorescent photochromic N-doped carbon dots nanocomposite ink was prepared.•Rice straw was used to prepare N-CDs ink via one-pot hydrothermal carbonization.•The anti-counterfeiting colorless ink changed to blue emission under UV light.•The printed sheets showed an effective reversible photochromism without fatigue.•Ink rheological performance of printed sheet mechanical properties were explored.
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.