Fluorescent Carbon Dots: Emerging Materials in Nanoscience

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 17126

Special Issue Editors


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Guest Editor
Institute for Physical and Chemical Processes, IPCF-National Research Council, CNR, Bari Division, c/o Chemistry Department, University of Bari “Aldo Moro”, 70125 Bari, Italy
Interests: nanomaterials; colloidal nanoparticles; quantum dots; carbon dots; perovskite nanocrystals; hybrids; nanocomposites; optical properties; self assembly and nanocrystal organization; chemical functionalization
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E-Mail Website
Guest Editor
Institute for Physical and Chemical Processes, IPCF -National Research Council, CNR, Bari Division, c/o Chemistry Department, University of Bari "Aldo Moro", Bari, 70125, Italy
Interests: colloidal nanocrystals; carbon dots; surface functionalization; nanocomposites; hybrid nanostructures; fluorescence; spectroscopic properties; energy transfer; optoelectronic devices; energy-related applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In the last few years, fluorescent carbon dots (CDots) have been revealed as an intriguing novel class of nanomaterials, thanks to their unique structural, physicochemical, and photochemical properties, including bright and tunable emissions covering the full visible spectrum, hydrophilicity, ease of surface processability, chemical stability, good biocompatibility, low toxicity, and cost-effectiveness, in terms of precursor availability and process-related demands. These interesting properties make fluorescent CDots promising materials for wide-field applications, embracing imaging, sensing, drug delivery, environmental catalysis, optoelectronics, and energy-related applications.

In view of the large interest raised in the scientific community by CDots, we encourage researchers to share their outputs on the synthesis, properties, and applications of such an appealing nanomaterial. This Special Issue’s key interests include advances on novel chemical synthetic approaches to obtain luminescent CDots, revealing the intimate correlation among structural, physical, and chemical properties, with particular attention to the emission mechanisms. Finally, we expect significant contributions to the extension of new applications for CDots, in functional materials, energy-related and light-emitting devices, catalysis, sensing, bioimaging, and biomedicine.

In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

  • Chemical and green approaches for the synthesis of fluorescent carbon dots;
  • Design and synthesis of red-emitting carbon dots;
  • Functionalization procedures;
  • Investigation of CDot properties as solvation and structural and optical correlation;
  • Polymeric nanocomposites and hybrids of carbon dots in host matrices;
  • Nanoformulations based on carbon dots in biological systems;
  • Emitting properties of carbon dots in solid-state films;
  • Modeling and simulations of carbon dots-based systems;
  • Carbon dots applications for sensing, energy-related and optoelectronic devices, white emission sources,  (bio)imaging and (bio)detection, (photo)catalysis, anticounterfeiting, and forensics.

Dr. Marinella Striccoli
Dr. Annamaria Panniello 
Guest Editors

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Keywords

  • carbon dots
  • fluorescence
  • red emission
  • nanocomposites
  • hybrid nanostructures
  • sustainable synthesis
  • green nanomaterials
  • sensors
  • white-emitting materials
  • biological nanovectors

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Published Papers (7 papers)

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Research

19 pages, 4688 KiB  
Article
Exploring the Impact of Nitrogen Doping on the Optical Properties of Carbon Dots Synthesized from Citric Acid
by Chiara Olla, Antonio Cappai, Stefania Porcu, Luigi Stagi, Marzia Fantauzzi, Maria Francesca Casula, Francesca Mocci, Riccardo Corpino, Daniele Chiriu, Pier Carlo Ricci and Carlo Maria Carbonaro
Nanomaterials 2023, 13(8), 1344; https://doi.org/10.3390/nano13081344 - 12 Apr 2023
Cited by 9 | Viewed by 3135
Abstract
The differences between bare carbon dots (CDs) and nitrogen-doped CDs synthesized from citric acid as a precursor are investigated, aiming at understanding the mechanisms of emission and the role of the doping atoms in shaping the optical properties. Despite their appealing emissive features, [...] Read more.
The differences between bare carbon dots (CDs) and nitrogen-doped CDs synthesized from citric acid as a precursor are investigated, aiming at understanding the mechanisms of emission and the role of the doping atoms in shaping the optical properties. Despite their appealing emissive features, the origin of the peculiar excitation-dependent luminescence in doped CDs is still debated and intensively being examined. This study focuses on the identification of intrinsic and extrinsic emissive centers by using a multi-technique experimental approach and computational chemistry simulations. As compared to bare CDs, nitrogen doping causes the decrease in the relative content of O-containing functional groups and the formation of both N-related molecular and surface centers that enhance the quantum yield of the material. The optical analysis suggests that the main emission in undoped nanoparticles comes from low-efficient blue centers bonded to the carbogenic core, eventually with surface-attached carbonyl groups, the contribution in the green range being possibly related to larger aromatic domains. On the other hand, the emission features of N-doped CDs are mainly due to the presence of N-related molecules, with the computed absorption transitions calling for imidic rings fused to the carbogenic core as the potential structures for the emission in the green range. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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21 pages, 3317 KiB  
Article
One-Pot Synthesis of Dual Color-Emitting CDs: Numerical and Experimental Optimization towards White LEDs
by Gianluca Minervini, Antonino Madonia, Annamaria Panniello, Elisabetta Fanizza, Maria Lucia Curri and Marinella Striccoli
Nanomaterials 2023, 13(3), 374; https://doi.org/10.3390/nano13030374 - 17 Jan 2023
Cited by 4 | Viewed by 1889
Abstract
Carbon Dots (CDs) are fluorescent carbon-based nanoparticles that have attracted increasing attention in recent years as environment-friendly and cost-effective fluorophores. An application that can benefit from CDs in a relatively short-term perspective is the fabrication of color-converting materials in phosphor-converted white LEDs (WLEDs). [...] Read more.
Carbon Dots (CDs) are fluorescent carbon-based nanoparticles that have attracted increasing attention in recent years as environment-friendly and cost-effective fluorophores. An application that can benefit from CDs in a relatively short-term perspective is the fabrication of color-converting materials in phosphor-converted white LEDs (WLEDs). In this work we present a one-pot solvothermal synthesis of polymer-passivated CDs that show a dual emission band (in the green and in the red regions) upon blue light excitation. A purposely designed numerical approach enables evaluating how the spectroscopic properties of such CDs can be profitable for application in WLEDs emulating daylight characteristics. Subsequently, we fabricate nanocomposite coatings based on the dual color-emitting CDs via solution-based strategies, and we compare their color-converting properties with those of the simulated ones to finally accomplish white light emission. The combined numerical and experimental approach can find a general use to reduce the number of experimental trial-and-error steps required for optimization of CD optical properties for lighting application. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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13 pages, 3331 KiB  
Article
Carbon Dot Emission Enhancement in Covalent Complexes with Plasmonic Metal Nanoparticles
by Irina A. Arefina, Danil A. Kurshanov, Anna A. Vedernikova, Denis V. Danilov, Aleksandra V. Koroleva, Evgeniy V. Zhizhin, Aleksandr A. Sergeev, Anatoly V. Fedorov, Elena V. Ushakova and Andrey L. Rogach
Nanomaterials 2023, 13(2), 223; https://doi.org/10.3390/nano13020223 - 4 Jan 2023
Cited by 1 | Viewed by 2376
Abstract
Carbon dots can be used for the fabrication of colloidal multi-purpose complexes for sensing and bio-visualization due to their easy and scalable synthesis, control of their spectral responses over a wide spectral range, and possibility of surface functionalization to meet the application task. [...] Read more.
Carbon dots can be used for the fabrication of colloidal multi-purpose complexes for sensing and bio-visualization due to their easy and scalable synthesis, control of their spectral responses over a wide spectral range, and possibility of surface functionalization to meet the application task. Here, we developed a chemical protocol of colloidal complex formation via covalent bonding between carbon dots and plasmonic metal nanoparticles in order to influence and improve their fluorescence. We demonstrate how interactions between carbon dots and metal nanoparticles in the formed complexes, and thus their optical responses, depend on the type of bonds between particles, the architecture of the complexes, and the degree of overlapping of absorption and emission of carbon dots with the plasmon resonance of metals. For the most optimized architecture, emission enhancement reaching up to 5.4- and 4.9-fold for complexes with silver and gold nanoparticles has been achieved, respectively. Our study expands the toolkit of functional materials based on carbon dots for applications in photonics and biomedicine to photonics. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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14 pages, 4081 KiB  
Article
Dual-Purpose Sensing Nanoprobe Based on Carbon Dots from o-Phenylenediamine: pH and Solvent Polarity Measurement
by Anna A. Vedernikova, Mikhail D. Miruschenko, Irina A. Arefina, Anton A. Babaev, Evgeniia A. Stepanidenko, Sergei A. Cherevkov, Igor G. Spiridonov, Denis V. Danilov, Aleksandra V. Koroleva, Evgeniy V. Zhizhin and Elena V. Ushakova
Nanomaterials 2022, 12(19), 3314; https://doi.org/10.3390/nano12193314 - 23 Sep 2022
Cited by 11 | Viewed by 2675
Abstract
Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they [...] Read more.
Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they demonstrate unique optical properties with intense emissions, biocompatibility, and ease of fabrication. Herein, we developed synthesis protocols to obtain CDs based on o-phenylenediamine with a variety of optical responses depending on additional precursors and changes in the reaction media. The obtained CDs are N-doped (N,S-doped in case of thiourea addition) less than 10 nm spherical particles with emissions observed in the 300–600 nm spectral region depending on their chemical composition. These CDs may act simultaneously as absorptive/fluorescent sensing probes for solvent polarity with S/ENT  up to 85, for ENT from 0.099 to 1.0 and for pH values in the range of 3.0–8.0, thus opening an opportunity to check the pH in non-pure water or a mixture of solvents. Moreover, CDs preserve their optical properties when embedded in cellulose strips that can be used as sensing probes for fast and easy pH checks. We believe that the resulting dual-purpose sensing nano probes based on CDs will have high demand in various sensing applications. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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10 pages, 5068 KiB  
Article
Dye Plants Derived Carbon Dots for Flexible Secure Printing
by Linlin Li, Yuanyuan Han, Lihua Wang, Wei Jiang and Haiguang Zhao
Nanomaterials 2022, 12(18), 3168; https://doi.org/10.3390/nano12183168 - 13 Sep 2022
Cited by 11 | Viewed by 1976
Abstract
Carbon dots (C-dots) are fluorescent nanomaterials, exhibiting excellent structure-dependent optical properties for various types of optical and electrical applications. Although many precursors were used for C-dots production, it is still a challenge to produce high-quality C-dots using environmentally-friendly natural precursors. In this work, [...] Read more.
Carbon dots (C-dots) are fluorescent nanomaterials, exhibiting excellent structure-dependent optical properties for various types of optical and electrical applications. Although many precursors were used for C-dots production, it is still a challenge to produce high-quality C-dots using environmentally-friendly natural precursors. In this work, multiple-colored colloidal C-dots were synthesized via a heating reaction using natural plant dyes as precursors, for example, Indigo, Carcuma longa, and Sophora japonica L. The as-prepared C-dots have absorption in the UV range of 220 to 450 nm with the typical emission ranging from 350 to 600 nm. The as-obtained C-dots have a quantum yield as high as 3.8% in an aqueous solution. As a proof-of-concept, we used the as-prepared C-dots as fluorescence inks for textile secure printing. The printed patterns are almost invisible under daylight and have distinct and clear patterns under 365 and 395 nm light, proving the great potential in optical anti-counterfeiting. This work demonstrates the advanced strategy for high-performance C-dots production from natural dyes and their potential application in flexible secure printing systems. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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14 pages, 4069 KiB  
Article
Multicolor Luminescent Carbon Dots: Tunable Photoluminescence, Excellent Stability, and Their Application in Light-Emitting Diodes
by Longshi Rao, Qing Zhang, Bin Sun, Mingfu Wen, Jiayang Zhang, Guisheng Zhong, Ting Fu and Xiaodong Niu
Nanomaterials 2022, 12(18), 3132; https://doi.org/10.3390/nano12183132 - 9 Sep 2022
Cited by 7 | Viewed by 1763
Abstract
Carbon dots (CDs) are attracting much interest due to their excellent photoelectric properties and wide range of potential applications. However, it is still a challenge to regulate their bandgap emissions to achieve full-color CDs with high emissions. Herein, we propose an approach for [...] Read more.
Carbon dots (CDs) are attracting much interest due to their excellent photoelectric properties and wide range of potential applications. However, it is still a challenge to regulate their bandgap emissions to achieve full-color CDs with high emissions. Herein, we propose an approach for producing full-color emissive CDs by employing a solvent engineering strategy. By only tuning the volume ratio of water and dimethylformamide (H2O/DMF), the photoluminescence (PL) emission wavelengths of the CDs can be changed from 451 to 654 nm. Different fluorescence features of multicolor CDs were systematically investigated. XRD, SEM, TEM, Abs/PL/PLE, XPS, and PL decay lifetime characterizations provided conclusive evidence supporting the extent to which the solvent controlled the dehydration and carbonization processes of the precursors, leading to a variation in their emission color from red to blue. The as-prepared CDs exhibited excellent and stable fluorescence performance even after being heated at 80 °C for 48 h and with UV light continuously irradiated for 15 h. Based on their excellent fluorescent properties and photothermal stability, bright multicolor light-emitting diodes with a high CRI of up to 91 were obtained. We anticipate that these full-color emissive CDs are beneficial for applications in lighting, display, and other fields. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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14 pages, 4384 KiB  
Article
Harnessing Molecular Fluorophores in the Carbon Dots Matrix: The Case of Safranin O
by Manuela Meloni, Luigi Stagi, Davide Sanna, Sebastiano Garroni, Laura Calvillo, Angela Terracina, Marco Cannas, Fabrizio Messina, Carlo Maria Carbonaro, Plinio Innocenzi and Luca Malfatti
Nanomaterials 2022, 12(14), 2351; https://doi.org/10.3390/nano12142351 - 9 Jul 2022
Cited by 3 | Viewed by 2111
Abstract
The origin of fluorescence in carbon dots (C-dots) is still a puzzling phenomenon. The emission is, in most of the cases, due to molecular fluorophores formed in situ during the synthesis. The carbonization during C-dots processing does not allow, however, a fine control [...] Read more.
The origin of fluorescence in carbon dots (C-dots) is still a puzzling phenomenon. The emission is, in most of the cases, due to molecular fluorophores formed in situ during the synthesis. The carbonization during C-dots processing does not allow, however, a fine control of the properties and makes finding the source of the fluorescence a challenging task. In this work, we present a strategy to embed a pre-formed fluorescent molecule, safranin O dye, into an amorphous carbonaceous dot obtained by citric acid carbonization. The dye is introduced in the melted solution of citric acid and after pyrolysis remains incorporated in a carbonaceous matrix to form red-emitting C-dots that are strongly resistant to photobleaching. Embedding dyes in amorphous C-dots represents an alternative method to optimize the emission in the whole visible spectrum. Full article
(This article belongs to the Special Issue Fluorescent Carbon Dots: Emerging Materials in Nanoscience)
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