Large‐Scale Green Synthesis of Fluorescent Carbon Nanodots and Their Use in Optics Applications

Abstract

precursors, which can be toxic or complicated to manipulate (e.g., citric acid and ethylediamine).[ 15 ] Consequently, tremendous efforts are still required to develop novel synthetic methods for the large-scale preparation of highly luminescent and water-dispersible C-dots with a high production yield. Taking advantage of several unique advantages, microwave irradiation (MWI) has been developed as a powerful synthetic tool. To date, several MWIassisted synthetic strategies have been developed for preparing various functional nanostructures, [16][17][18] including our recent success in the synthesis of fl uorescent II-VI quantum dots and silicon nanostructures. [ 17,[19][20][21][22][23] For example, ∼0.1 g fl uorescent silicon nanoparticles (SiNPs) can be rapidly prepared in 10 min under microwave irradiation. [ 23 ] Inspired by these studies, we herein introduce a microwaveassisted strategy for the large-scale synthesis of highly luminescent (quantum yield (QY): ∼16%) and water-dispersible C-dots. Remarkably, ∼0.3 g C-dots can be rapidly achieved in a 25-min reaction with an adaptable production yield of ∼25% by using 20 mL milk, which is widely recognized as a green carbonaceous resource and readily purchased from a local market. It is worth noting that, in addition to milk, other kinds of green carbonaceous resources (e.g., soybean milk, honey, silk, hair, lemon, and magnolia) are also available for the preparation of luminescent C-dots (see experiment details in the Supporting Information). Our experiment further demonstrates that the prepared luminescent C-dots are highly promising as fl uorescent stains for a variety of optics-related applications, including in vitro and in vivo bioimaging, printing inks, and sensors, as shown in Scheme 1 . Results and DiscussionFigure 1 a presents typical UV-vis and photoluminescent spectra of the synthesized C-dots, showing distinct absorption and emission peaks at 275 and 480 nm, respectively. The aqueous solution of C-dots displays strong blue fl uorescence when the sample is irradiated by UV light, indicating strong fl uorescence of the C-dots. In addition to this, the sample solution is highly transparent under ambient conditions, suggesting the An easy and green synthetic strategy for the one-pot large-scale preparation of carbon nanodots (C-dots) is demonstrated. The C-dots have a series of excellent optical features such as strong fl uorescence and excitationwavelength-dependent photoluminescence properties. Notably, C-dots can be rapidly and facilely achieved on a large scale (e.g., 0.3 g C-dots/25 min) by using cheap, accessible, and natural materials (e.g., milk, honey, silk, hair, lemon, and magnolia) as the green carbonaceous precursor. The as-prepared C-dots, which are shown to serve as high-performance fl uorescent stains, are superbly suitable for a variety of optics-related applications, including in vitro and in vivo bioimaging, printing inks, and sensors. Eventually, this kind of microwave-assisted strategy could serve as a powerful tool for synthesizing...

Natural‐Product‐Derived Carbon Dots: From Natural Products to Functional Materials

“…Recently,d ifferent groups have described many applications based on NCDs, including coding, [99] imaging, [53,68,76,[100][101][102] sensing, [70,81,101] catalysis, [13] sensitizing solar cells, [103] photoacoustic imaging, [104] and printing. [105] In the following sections, we will discusst he use of NCDs in bioimaging, catalysis, and sensing and as sensitizers for solar cells.…”

One-Step Microwave-Assisted Green Synthesis of Luminescent N-Doped Carbon Dots from Sesame Seeds for Selective Sensing of Fe(III)

“…Some studies have already been reported in this direction; Qian et al 29 used the N-doped C.dots for detection of Fe(III). Wang et al 30 used a wide variety of green carbonaceous precursors like milk, silk, honey, hair, lemon, etc. to detect Fe(III).…”

Fluorescent carbon nanoparticles for sensitive and selective detection of palladium (Pd2+)

“…Currently many optical and electronic properties of CNPs have not been well controlled because of the unpredictable synthesis process of CNPs, resulting in the unpredictable chemical structure of CNPs. Although CNPs synthesis using inexpensive, recycling source and easy obtained natural materials, such as food waste 44 , milk 34 , cotton 29 and soy milk 45 as precursors have gained much attention as green synthetic route in recent years, the complicity of the precursors could cause more obstacles in…”

“…In addition, the bright blue and green patterns still could be observed after several months, demonstrating the excellent photostability of CNPs. Wang et al 34 developed a simple and large-scale preparation route of CNPs.…”