Abstract
In this study, a simple and green hydrothermal treatment was performed to prepare nitrogen-doped carbon dots (NCDs) from Averrhoa carambola (AC) fruit extract as a carbon precursor and L-arginine (Arg) as a nitrogen dopant. The AC-NCDs were characterized by UV light, fluorescence spectroscopy, transmission electron microscopy, FTIR spectroscopy, Raman spectroscopy, UV-vis spectroscopy, and zeta potential analyzer. The AC-NCDs were spherical and the average diameter was estimated to be 6.67 nm. The AC-NCDs exhibited the maximum emission intensity at 446 nm with 360 nm excitation wavelength. The fluorescence quenching behavior of AC-NCDs after interacting with methyl orange (MO) dye was studied. The interaction of AC-NCDs and MO was achieved within 3 min and the fluorescence quenching was maintained to a fixed value even after 30 min. The linearity was obtained in the range of 1 to 25 μM MO with a 0.30 μM detection limit. Furthermore, the pH values affected the quenching behavior of the AC-NCDs/MO system where the interaction mechanisms were driven by the electrostatic interaction, π–π interaction, inner filter effect, and energy transfer. The pH 5 maintained higher quenching efficiency while other pH values slightly decreased the quenching efficiency. Incoming applications, the AC-NCDs can be used in various important fields, especially for environmental protection.
Highlights
Carbon dots (CDs) exhibiting strong fluorescent properties with excitation-dependent emissions have arrested much attention [1]
L-arginine (Arg), an amino acid, has been chosen as N-dopant to react with the primary carbon precursor (AC fruit extract) which has N content approximately 32% [14]
The highest emission intensity was obtained with 75% of the solvent mixed with the Averrhoa carambola (AC) fruit extract (Figure S1a)
Summary
Carbon dots (CDs) exhibiting strong fluorescent properties with excitation-dependent emissions have arrested much attention [1]. (S), and phosphor (P) were commonly added to functionalize CDs [4] Among these heteroatoms, N-dopant is a widely used dopant to increase the fluorescent properties of CDs. Nowadays, the chemistry concepts of economical and green materials attract much attention to the synthesis of CDs. Cheap and available natural resources are still challengeable as the carbon precursors to produce CDs [6]. It is needed to promote facile, simple, and efficient methods Toward this objective, a facile and green hydrothermal treatment was adopted to synthesize AC-nitrogen-doped carbon dots (AC-NCDs) from AC fruit extract and. As far as we know, there is no other report on the production of NCDs utilizing AC fruit extract with Arg. The use of other NCDs as fluorescent probes for MO detection has not been declared. Synthesis and application as a fluorescent probe for methyl orange (MO)
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