Preparation of Carbon Dots from Cellulose Using Ionic Liquid under Mild Condition
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ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version)
Preparation of Carbon Dots from Cellulose Using Ionic Liquid under Mild Condition Jeongyeon Woo†, Hyungsup Kim†, and Younghan Song* Department of Organic and Nano System Engineering, Konkuk University, Seoul 05029, Korea (Received August 28, 2019; Revised November 26, 2019; Accepted December 7, 2019) Abstract: This research focused on the preparation of carbon dots (CDs) using cellulose hydrolysis in ionic liquid (IL) at a low temperature of 65 oC without additional treatments. The morphologies of the CDs were observed by TEM. The chemical structures and the optical properties were characterized by XPS, FT-IR, UV-vis and PL spectroscopies. As the cellulose was incubated longer in the IL, the size of the CDs was reduced. Besides, the core of the CD was simultaneously nitrogen-doped more with graphitic N, resulting in the increase of the quantum yield up to ~33 %. For the easier application of the CD in solid state, the CD embedded cellulose film was simply prepared via the one-pot dissolution. The prepared cellulose film showed excellent photoluminescence behaviors as well as the superior transparency of over 97 % in the visible light region. Keywords: Cellulose, Ionic liquid, Carbon dots, Photoluminescence film, Mild condition
example, the reduction of the molar mass in ILs enhanced the molecular mobility of the cellulose, resulting in ordered crystalline after regeneration [14]. As another example, 20 nm sized nanoparticles could be prepared via the selfassembly of the positively charged cellulose chains by the reaction with ILs [13]. However, there were few studies on the formation of the carbonaceous materials in the course of the cellulose decomposition in ILs. Dee and Bell studied the conversion of cellulose to glucose by ILs. In addition to the formation of glucose, they demonstrated that humins (solid residues) can be formed though the condensation and polymerization of the sugars in the ILs [18]. Wang at al. reported a fabrication method of carbon dots (CDs) from cellulose via two-step treatment using 1-buthyl-3methylimiazolium chloride as a solvent and SO3Hfunctionallized acidic ILs as a catalyst [19]. The acidic ILs as a catalyst promoted the conversion of cellulose to carbon dots. The resulted CDs showed excellent fluorescent probe for the detection of Hg2+. Still, the CDs showed a low quantum yield of 4.7 %. Herein, we represent a fabrication process for CDs from cellulose using 1-buthyl-3-methylimidazolium acetate at a low temperature of 65 oC via an one-step synthesis. Along the duration time of cellulose in IL, the chemical structure and the optical properties of the synthesized CDs were investigated by X-ray photoelectron, Fourier-transform infrared, UV-vis, and photoluminescent spectroscopies. Moreover, a transparent and photoluminescent cellulose film was successfully prepared via an one-pot synthesis of CDs using the cellulose/IL solution without any purification for CDs.
Introduction Cellulose is one of the widely used materia
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