Gel-like Carbon Dots: Characterization and their Potential Applications.
Highly photoluminescent gel-like carbon dots (G-CDs) were successfully synthesized for the first time by a rapid one-step solvothermal synthesis approach with citric acid and 1,2-ethylenediamine as the precursors. Their gel-like nature was revealed by the Tyndall and coagulation effects, which were elucidated by a negative ζ potential value. The influences of temperature on the properties and sizes of these G-CDs were analyzed, and the best method for a maximum quantum yield was identified. The resulting products emitted blue photoluminescence under UV light (λ=365 nm) and a gradient of color under regular light. In addition, the UV/Vis absorption and fluorescence emission spectra of the G-CDs indicated that those synthesized at 160 °C exhibited the highest fluorescence quantum yield (33 %). Atomic force microscopy and transmission electron microscopy measurements were performed, and a higher temperature of formation resulted in smaller G-CDs. Furthermore, band shifts in the UV/Vis and fluorescence spectra and sequential changes in the quantum yield values and ζ potentials in addition to elemental compositional changes as determined by X-ray photoelectron spectroscopy were monitored throughout the formation process of the G-CDs. As to applications, G-CDs were prepared as an invisible ink for printers, which exhibited the applicability of G-CDs in daily life and military activities.
Department of Chemistry, University of Miami, Coral Gables, Florida, 33146, USA.
Yiqun
Y
Zhou
CESI Engineering School, 16000, Angoulême, Charente, France.
Alexandra
A
Desserre
Department of Chemistry, University of Miami, Coral Gables, Florida, 33146, USA.
Shiv K
SK
Sharma
Department of Chemistry, University of Miami, Coral Gables, Florida, 33146, USA.
Shanghao
S
Li
Department of Chemistry, Middle Tennessee State University, Murfreesboro, Tennessee, 37132, USA.
M Hensley
MH
Marksberry
Department of Chemistry, Middle Tennessee State University, Murfreesboro, Tennessee, 37132, USA.
Charles C
CC
Chusuei
Department of Chemistry, University of Miami, Coral Gables, Florida, 33146, USA.|GS/RSMAS, University of Miami, Key Biscayne, Florida, 33149, USA.
Patricia L
PL
Blackwelder
Department of Chemistry, University of Miami, Coral Gables, Florida, 33146, USA.
Roger M
RM
Leblanc
carbon dots; gels; invisible inks; photoluminescence; quantum dots