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Kumara BN, Kalimuthu P, Prasad KS. Synthesis, properties and potential applications of photoluminescent carbon nanoparticles: A review. Anal Chim Acta 2023; 1268:341430. [PMID: 37268342 DOI: 10.1016/j.aca.2023.341430] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 05/24/2023] [Accepted: 05/24/2023] [Indexed: 06/04/2023]
Abstract
Photoluminescent-carbon nanoparticles (PL-CNPs) are a new class of materials that received immense interest among researchers due to their distinct characteristics, including photoluminescence, high surface-to-volume ratio, low cost, ease of synthesis, high quantum yield, and biocompatibility. By exploiting these outstanding properties, many studies have been reported on its utility as sensors, photocatalysts, probes for bio-imaging, and optoelectronics applications. From clinical applications to point-of-care test devices, drug loading to tracking of drug delivery, and other research innovations demonstrated PL-CNPs as an emerging material that could substitute conventional approaches. However, some of the PL-CNPs have poor PL properties and selectivity due to the presence of impurities (e.g., molecular fluorophores) and unfavourable surface charges by the passivation molecules, which impede their applications in many fields. To address these issues, many researchers have been paying great attention to developing new PL-CNPs with different composite combinations to achieve high PL properties and selectivity. Herein, we thoroughly discussed the recent development of various synthetic strategies employed to prepare PL-CNPs, doping effects, photostability, biocompatibility, and applications in sensing, bioimaging, and drug delivery fields. Moreover, the review discussed the limitations, future direction, and perspectives of PL-CNPs in possible potential applications.
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Affiliation(s)
- B N Kumara
- Nanomaterial Research Laboratory (NMRL), Nano Division, Yenepoya Research Centre, Yenepoya (Deemed to Be University), Deralakatte, Mangalore, 575 018, India
| | - Palraj Kalimuthu
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, 4072, Australia.
| | - K S Prasad
- Centre for Nutrition Studies, Yenepoya (Deemed to Be University), Deralakatte, Mangalore, 575 018, India.
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2
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Crista D, Algarra M, Martínez de Yuso MV, Esteves da Silva JCG, Pinto da Silva L. Investigation of the role of pH and the stoichiometry of the N-dopant in the luminescence, composition and synthesis yield of carbon dots. J Mater Chem B 2023; 11:1131-1143. [PMID: 36637160 DOI: 10.1039/d2tb02318k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Carbon dots (CDs) are carbon-based nanoparticles with very attractive luminescence features, which simplicity and flexibility of their fabrication can lead to an endless number of CDs with distinct properties and applications. High fluorescence quantum yields (QYFL) are generally a necessary feature for various applications of CDs. One commonly employed strategy to improve the fluorescence properties of CDs is heteroatom-doping using precursors containing desired heteroatoms (with focus on N-doping). In this work, we report the synthesis and systematic investigation of an array of N-doped CDs, obtained from the dry heating of solid mixtures of glucose and urea in different molar ratios with two main objectives: to study the role of stoichiometry in the optical properties and composition of CDs and to investigate the formation of possible alkaline-responsive nanoparticles and the potential of this procedure for obtaining CDs with higher synthesis yields. We have characterized the optical properties of this diverse array of glucose and urea-based CDs using both UV-Vis and fluorescence spectroscopies. In addition, we have also examined the CDs by using high-resolution transmission electron microscopy (HR-TEM) and X-Ray photoelectron (XPS) spectroscopy, as well as by assessing the thermal stability of the nanoparticles. We have found that this fabrication process generates two types of CDs, one readily soluble in water and other only soluble at basic pH. The latter was characterized by higher synthesis yields, and lower QYFL and thermal stability, when compared with those of the former. Furthermore, the stoichiometry of the N-dopant does not appear to be correlated with the QYFL of the obtained CDs. This study provides novel information that should be useful for the future rational development of CDs with higher QYFL and synthesis yields.
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Affiliation(s)
- Diana Crista
- Chemistry Research Unit (CIQUP), Institute of Molecular Sciences (IMS), Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences, University of Porto, R. Campo Alegre s/n, 4169-007 Porto, Portugal.
| | - Manuel Algarra
- INAMAT2-Institute for Advanced Materials and Mathematics, Department of Science, Public University of Navarra, Campus of Arrosadía, 31006 Pamplona, Spain.
| | - Maria Valle Martínez de Yuso
- X-ray Photoelectron Spectroscopy Lab. Central Service to Support Research Building (SCAI), University of Málaga, 29071 Málaga, Spain
| | - Joaquim C G Esteves da Silva
- Chemistry Research Unit (CIQUP), Institute of Molecular Sciences (IMS), Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences, University of Porto, R. Campo Alegre s/n, 4169-007 Porto, Portugal. .,LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences, University of Porto, R. Campo Alegre s/n, 4169-007 Porto, Portugal
| | - Luís Pinto da Silva
- Chemistry Research Unit (CIQUP), Institute of Molecular Sciences (IMS), Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences, University of Porto, R. Campo Alegre s/n, 4169-007 Porto, Portugal. .,LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences, University of Porto, R. Campo Alegre s/n, 4169-007 Porto, Portugal
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3
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Applications of Fluorescent Carbon Dots as Photocatalysts: A Review. Catalysts 2023. [DOI: 10.3390/catal13010179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Carbon dots (CDs) have attracted considerable interest from the scientific community due to their exceptional properties, such as high photoluminescence, broadband absorption, low toxicity, water solubility and (photo)chemical stability. As a result, they have been applied in several fields, such as sensing, bioimaging, artificial lighting and catalysis. In particular, CDs may act as sole photocatalysts or as part of photocatalytic nanocomposites. This study aims to provide a comprehensive review on the use of CDs as sole photocatalysts in the areas of hydrogen production via water splitting, photodegradation of organic pollutants and photoreduction and metal removal from wastewaters. Furthermore, key limitations preventing a wider use of CDs as photocatalysts are pointed out. It is our hope that this review will serve as a basis on which researchers may find useful information to develop sustainable methodologies for the synthesis and use of photocatalytic CDs.
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Graphene Quantum Dots and Phthalocyanines Turn-OFF-ON Photoluminescence Nanosensor for ds-DNA. NANOMATERIALS 2022; 12:nano12111892. [PMID: 35683746 PMCID: PMC9182175 DOI: 10.3390/nano12111892] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 02/06/2023]
Abstract
Supramolecular hybrids of graphene quantum dots (GQDs) and phthalocyanine (Pc) dyes were studied as turn-OFF-ON photoluminescence nanosensors for detection of ds-DNA. Pcs with four (Pc4) and eight (Pc8) positive charges were selected to interact with negatively charged GQDs. The photoluminescence of the GQDs was quenched upon interaction with the Pcs, due to the formation of non-emissive complexes. In the presence of ds-DNA, the Pcs interacted preferentially with the negatively charged ds-DNA, lifting the quenching effect over the photoluminescence of the GQDs and restoring their emission intensity. The best performance as a sensor of ds-DNA was registered for the GQD-Pc8, with a limit of detection (LOD) in the picomolar range. The LOD for GQD-Pc8 was more than one order of magnitude lower and its sensitivity was about a factor of three higher than that of the analogue GQD-Pc4 nanosensor. The sensitivity and selectivity of this simple GQD-Pc8 nanosensor is comparable to those of the more sophisticated carbon-based nanosensors for DNA reported previously.
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Life Cycle Assessment-Based Comparative Study between High-Yield and "Standard" Bottom-Up Procedures for the Fabrication of Carbon Dots. MATERIALS 2022; 15:ma15103446. [PMID: 35629474 PMCID: PMC9145381 DOI: 10.3390/ma15103446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 02/01/2023]
Abstract
Carbon dots (CDs) are carbon-based nanomaterials with remarkable properties that can be produced from a wide variety of synthesis routes. Given that “standard” bottom-up procedures are typically associated with low synthesis yields, different authors have been trying to devise alternative high-yield fabrication strategies. However, there is a doubt if sustainability-wise, the latter should be really preferred to the former. Herein, we employed a Life Cycle Assessment (LCA) approach to compare and understand the environmental impacts of high-yield and “standard” bottom-up strategies, by applying different life cycle impact assessment (LCIA) methods. These routes were: (1) production of hydrochar, via the hydrothermal treatment of carbon precursors, and its alkaline peroxide treatment into high-yield CDs; (2) microwave treatment of carbon precursors doped with ethylenediamine; (3) and (6) thermal treatment of carbon precursor and urea; (4) hydrothermal treatment of carbon precursor and urea; (5) microwave treatment of carbon precursor and urea. For this LCA, four LCIA methods were used: ReCiPe, Greenhouse Gas Protocol, AWARE, and USEtox. Results identified CD-5 as the most sustainable synthesis in ReCiPe, Greenhouse Gas Protocol, and USEtox. On the other hand, in AWARE, the most sustainable synthesis was CD-1. It was possible to conclude that, in general, high-yield synthesis (CD-1) was not more sustainable than “standard” bottom-up synthesis, such as CD-5 and CD-6 (also with relatively high-yield). More importantly, high-yield synthesis (CD-1) did not generate much lower environmental impacts than “standard” approaches with low yields, which indicates that higher yields come with relevant environmental costs.
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Zhao T, Chen R, Sun A, Xu L, Liu X. Dual-model spectral sensing of D-fructose of a large linear range. CHEMICAL PAPERS 2021. [DOI: 10.1007/s11696-021-01784-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Manoj D, Shanmugasundaram S, Anandharamakrishnan C. Nanosensing and nanobiosensing: Concepts, methods, and applications for quality evaluation of liquid foods. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.108017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Fernandes S, Esteves da Silva JCG, Pinto da Silva L. Comparative life cycle assessment of high-yield synthesis routes for carbon dots. NANOIMPACT 2021; 23:100332. [PMID: 35559833 DOI: 10.1016/j.impact.2021.100332] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 05/25/2023]
Abstract
Carbon dots (CDs) are carbon-based nanomaterials with advantageous luminescent properties, making them promising alternatives to other molecular and nanosized fluorophores. However, the development of CDs is impaired by the low synthesis yield of standard fabrication strategies, making high-yield strategies essential. To help future studies to focus on cleaner production strategies, we have employed a Life Cycle Assessment (LCA) to compare and understand the environmental impacts of available routes for the high-yield synthesis of carbon dots. These routes were: (1) production of hydrochar, via hydrothermal treatment of carbon precursors, and its alkaline-peroxide treatment into high-yield carbon dots; (2) thermal treatment of carbon precursors mixed in a eutectic mixture of salts. Results show that the first synthesis route is associated with the lowest environmental impacts. This is attributed to the absence of the mixture of salts in the first synthesis route, which offsets its higher electricity consumption. Sensitivity analysis showed that the most critical parameter in the different synthetic strategies is the identity of the carbon precursor, with electricity being also relevant for the first synthesis route. Nevertheless, the use of some carbon precursors (as citric acid) with higher associated environmental impacts may be justified by their beneficial role in increasing the luminescent performance of carbon dots. Thus, the first synthesis route is indicated to be the most environmental benign and should be used as a basis in future studies aimed to the cleaner and high-yield production of carbon dots.
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Affiliation(s)
- Sónia Fernandes
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Joaquim C G Esteves da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; LACOMEPHI, GreenUPorto, Department of Geosciences, Environmental and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Luís Pinto da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; LACOMEPHI, GreenUPorto, Department of Geosciences, Environmental and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal.
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9
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Evaluation of Different Bottom-up Routes for the Fabrication of Carbon Dots. NANOMATERIALS 2020; 10:nano10071316. [PMID: 32635483 PMCID: PMC7407658 DOI: 10.3390/nano10071316] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/26/2020] [Accepted: 07/02/2020] [Indexed: 02/07/2023]
Abstract
Carbon dots (CDs) are carbon-based nanoparticles with very attractive luminescence features. Furthermore, their synthesis by bottom-up strategies is quite flexible, as tuning the reaction precursors and synthesis procedures can lead to an endless number of CDs with distinct properties and applications. However, this complex variability has made the characterization of the structural and optical properties of the nanomaterials difficult. Herein, we performed a systematic evaluation of the effect of three representative bottom-up strategies (hydrothermal, microwave-assisted, and calcination) on the properties of CDs prepared from the same precursors (citric acid and urea). Our results revealed that these synthesis routes led to nanoparticles with similar sizes, identical excitation-dependent blue-to-green emission, and similar surface-functionalization. However, we have also found that microwave and calcination strategies are more efficient towards nitrogen-doping than hydrothermal synthesis, and thus, the former routes are able to generate CDs with significantly higher fluorescence quantum yields than the latter. Furthermore, the different synthesis strategies appear to have a role in the origin of the photoluminescence of the CDs, as hydrothermal-based nanoparticles present an emission more dependent on surface states, while microwave- and calcination-based CDs present an emission with more contributions from core states. Furthermore, calcination and microwave routes are more suitable for high-yield synthesis (~27-29%), while hydrothermal synthesis present almost negligible synthesis yields (~2%). Finally, life cycle assessment (LCA) was performed to investigate the sustainability of these processes and indicated microwave synthesis as the best choice for future studies.
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Crista DMA, El Mragui A, Algarra M, Esteves da Silva JCG, Luque R, Pinto da Silva L. Turning Spent Coffee Grounds into Sustainable Precursors for the Fabrication of Carbon Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E1209. [PMID: 32575837 PMCID: PMC7353129 DOI: 10.3390/nano10061209] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/13/2020] [Accepted: 06/18/2020] [Indexed: 01/24/2023]
Abstract
Spent coffee grounds (SCGs) are known for containing many organic compounds of interest, including carbohydrates, lipids, phenolic compounds and proteins. Therefore, we investigated them as a potential source to obtain carbon dots (CDs) via a nanotechnology approach. Herein, a comparison was performed between CDs produced by SCGs and classic precursors (e.g., citric acid and urea). The SCG-based CDs were obtained via the one-pot and solvent-free carbonization of solid samples, generating nanosized particles (2.1-3.9 nm). These nanoparticles exhibited a blue fluorescence with moderate quantum yields (2.9-5.8%) and an excitation-dependent emission characteristic of carbon dots. SCG-based CDs showed potential as environmentally relevant fluorescent probes for Fe3+ in water. More importantly, life cycle assessment studies validated the production of CDs from SCG samples as a more environmentally sustainable route, as compared to those using classic reported precursors, when considering either a weight- or a function-based functional unit.
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Affiliation(s)
- Diana M. A. Crista
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (D.M.A.C.); (A.E.M.); (J.C.G.E.d.S.)
| | - Abderrahim El Mragui
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (D.M.A.C.); (A.E.M.); (J.C.G.E.d.S.)
| | - Manuel Algarra
- Department of Inorganic Chemistry, Faculty of Science, University of Málaga, Campus de Teatino s/n, 29071 Málaga, Spain
| | - Joaquim C. G. Esteves da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (D.M.A.C.); (A.E.M.); (J.C.G.E.d.S.)
- LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Rafael Luque
- Departamento de Química Orgánica, Universidad de Córdoba, Edif. Marie Curie, Ctra N-IVA Km 396, E-14014 Córdoba, Spain
- Center for Molecular Design and Synthesis of Innovative compounds for Medicine, Peoples Friendship University of Russia (RUDN University), 6 Miklukho Maklaya Street, 117198 Moscow, Russia
| | - Luís Pinto da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (D.M.A.C.); (A.E.M.); (J.C.G.E.d.S.)
- LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
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Yang S, Zhang Y, Xue Y, Lu S, Yang H, Yang L, Ding C, Yu S. Cross-Linked Polyamide Chains Enhanced the Fluorescence of Polymer Carbon Dots. ACS OMEGA 2020; 5:8219-8229. [PMID: 32309732 PMCID: PMC7161025 DOI: 10.1021/acsomega.0c00510] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 03/17/2020] [Indexed: 05/15/2023]
Abstract
Carbon dots (CDs) have attracted tremendous attention for their outstanding advantages in luminescence. Here, α-amino-substituted lysine derivatives with the determined chemical structure were employed as precursors to obtain bright and highly stable fluorescent CDs through a facile hydrothermal route. The relationships among the chemical structure of precursors, CD fluorescence, and particle size were investigated. The results indicated that increased numbers of functional groups in precursors could promote the degree of cross-linking and lead to a smaller size, better fluorescent properties, and stronger stability of CDs. The C-CDs that were prepared from lysine derivatives with most functional groups showed excitation-dependent dual excitation and dual emission (DE2), high-stability luminescence, strong resistance to photobleaching, and high selectivity to Fe3+ and could be used as a sensitive probe for Fe3+ detection.
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Affiliation(s)
- Shouning Yang
- Collaborative
Innovation Center of Henan Province for Green Manufacturing of Fine
Chemicals, Henan Key Laboratory of Green Chemical Media and Reactions,
School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
| | - Yanmin Zhang
- Collaborative
Innovation Center of Henan Province for Green Manufacturing of Fine
Chemicals, Henan Key Laboratory of Green Chemical Media and Reactions,
School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
| | - Yuyan Xue
- Institute
of Mass Spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Sijia Lu
- Collaborative
Innovation Center of Henan Province for Green Manufacturing of Fine
Chemicals, Henan Key Laboratory of Green Chemical Media and Reactions,
School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
| | - Huayan Yang
- Collaborative
Innovation Center of Henan Province for Green Manufacturing of Fine
Chemicals, Henan Key Laboratory of Green Chemical Media and Reactions,
School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
| | - Lin Yang
- Collaborative
Innovation Center of Henan Province for Green Manufacturing of Fine
Chemicals, Henan Key Laboratory of Green Chemical Media and Reactions,
School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
| | - Chuanfan Ding
- Institute
of Mass Spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Shaoning Yu
- Institute
of Mass Spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China
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Christé S, Esteves da Silva JC, Pinto da Silva L. Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E504. [PMID: 31973126 PMCID: PMC7040597 DOI: 10.3390/ma13030504] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 02/02/2023]
Abstract
The efficiency and associated environmental impacts of different N-doping strategies of carbon dots (CDs) were evaluated. More specifically, N-doped CDs were prepared from citric acid via two main synthesis routes: Microwave-assisted hydrothermal treatment with addition of N-containing small organic molecules (urea and ethylenediamine (EDA)); and microwave-assisted solvothermal treatment in N-containing organic solvents (n,n-dimethylformamide (DMF), acetonitrile and pyridine). These syntheses produced CDs with similar blue emission. However, XPS analysis revealed that CDs synthesized via both hydrothermal routes presented a better N-doping efficiency (~15 at.%) than all three solvothermal-based strategies (0.6-7 at.%). However, from the former two hydrothermal strategies, only the one involving EDA as a nitrogen-source provided a non-negligible synthesis yield, which indicates that this should be the preferred strategy. This conclusion was supported by a subsequent life cycle assessment (LCA) study, which revealed that this strategy is clearly the most sustainable one from all five studied synthesis routes.
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Affiliation(s)
- Suzanne Christé
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (S.C.); (J.C.G.E.d.S.)
| | - Joaquim C.G. Esteves da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (S.C.); (J.C.G.E.d.S.)
- LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Luís Pinto da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal; (S.C.); (J.C.G.E.d.S.)
- LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
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Sendão RMS, Crista DMA, Afonso ACP, Martínez de Yuso MDV, Algarra M, Esteves da Silva JCG, Pinto da Silva L. Insight into the hybrid luminescence showed by carbon dots and molecular fluorophores in solution. Phys Chem Chem Phys 2019; 21:20919-20926. [PMID: 31517344 DOI: 10.1039/c9cp03730f] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Carbon dots have attracted great attention from the research community given their very attractive luminescent properties. However, the recent discovery that some of these properties may result from fluorescent impurities originating from the synthesis process, and not from the carbon dots themselves, constitute a significant setback to our knowledge of these materials. Herein, we proceeded to the study of carbon dots generated from citric acid and urea via a microwave-assisted synthesis, focusing on their analysis by AFM, HR-TEM, XPS, FT-IR, ESI-MS, UV-Vis and fluorescence spectroscopy. We have found that this synthesis process does generate molecular fluorophores that can mask the luminescence of the carbon dots. More importantly, our data demonstrates that when present in the same solution, the carbon dots and these fluorophores do not behave as separated species with individual emission. Instead, they interact to produce a hybrid luminescence, which excited state properties and reactivity are different from the properties of the individual species. These results indicate the possibility for the development of hybrid materials composed by carbon dots and related molecular fluorophores with new and improved properties.
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Affiliation(s)
- Ricardo M S Sendão
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Diana M A Crista
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Ana Carolina P Afonso
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal
| | - Maria Del Valle Martínez de Yuso
- X-Ray Photoelectron Spectroscopy Lab, Central Service to Support Research Bulding (SCAI), University of Málaga, 29071 Málaga, Spain
| | - Manuel Algarra
- CQM-Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
| | - Joaquim C G Esteves da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal and LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal.
| | - Luís Pinto da Silva
- Chemistry Research Unit (CIQUP), Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal and LACOMEPHI, GreenUPorto, Department of Geosciences, Environment and Territorial Planning, Faculty of Sciences of University of Porto, R. Campo Alegre 697, 4169-007 Porto, Portugal.
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