Insight into the hybrid luminescence showed by carbon dots and molecular fluorophores in solution

Sendão, Ricardo M S; Crista, Diana M A; Afonso, Ana Carolina P.; Yuso, María del Valle Martínez de; Algarra, Manuel Martín; Silva, Joaquim C. G. Esteves da; Silva, Luís Pinto da

doi:10.1039/c9cp03730f

Cited by 50 publications

(41 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The same can also be said for the differences between the fluorescence spectra of sample 1 and samples 2-5. In fact, the absorption, fluorescence excitation and emission spectra of sample 1 are in line with the fluorescent impurities generated in a similar synthesis of CDs from CA and urea [17].…”

Section: Improvement On the Purification Of Ca-urea Carbon Dotssupporting

confidence: 73%

“…The first approach is based on the breakdown of large graphite materials in smaller carbon-based materials [16]. However, bottom-up methods, such as microwave-assisted processes [17][18][19][20], appear to be the most widely used for the preparation of CDs, which consist of the synthesis of CDs from smaller carbon precursors (small organic molecules) [21,22]. Among these, citric acid (CA) is one of the most used [17,[23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

“…More importantly, N-doping generally enhances the fluorescence quantum yield (QY FL ) of the CDs [27][28][29], which has made N-doping one of the main strategies for enhancing the photoluminescence of CDs [3,30,31]. N-doping is generally achieved by adding a nitrogen-rich small organic molecule as a nitrogen precursor to the carbon precursor in hydrothermal-based bottom-up synthetic routes, with typical nitrogen precursors being molecules such as urea [17,26] and EDA [32,33].…”

Section: Introductionmentioning

confidence: 99%

“…Herein, the aim of this work was to assess the efficiency and sustainability of different N-doping strategies employed during the synthesis. Namely, CDs prepared from CA (a typical carbon precursor [17,[23][24][25][26]) were N-doped via two different strategies: (1) Microwave-assisted hydrothermal synthesis with addition of N-containing small organic molecules (urea or EDA), which are typically used as nitrogen precursors [17,26,32,33]; (2) microwave-assisted solvothermal synthesis in an N-containing solvent (DMF, acetonitrile or pyridine). The first step of this study was the characterization of the obtained CDs by X-ray photoelectron spectroscopy (XPS), UV-Visible (UV-Vis) spectroscopy and fluorescence spectroscopy, and by dynamic light scattering (DLS), which allowed us to determine the efficiency of N-doping and its effects on the photoluminescence of the CDs.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Christé

Silva

2020

Materials

View full text Add to dashboard Cite

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.

show abstract

Section: Improvement On the Purification Of Ca-urea Carbon Dotssupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Christé

Silva

2020

Materials

View full text Add to dashboard Cite

show abstract

“…CDs have attracted significant attention from the research community due to their quite remarkable features, such as high photoluminescence [2,9,10], low toxicity [11], good water solubility [2,12], biocompatibility [13,14], and good physical-chemical and photochemical stability [12,15,16].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Different Bottom-up Routes for the Fabrication of Carbon Dots

Crista

Silva

2020

Nanomaterials

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Carbon Dots–TiO₂Nanocomposites for the Enhanced Visible‐Light Driven Photodegradation of Methylene Blue

Sendão,

Algarra,

Ribeiro

et al. 2023

Advanced Sustainable Systems

Self Cite

View full text Add to dashboard Cite

Herein, the conjugation of carbon dots (CDs) with TiO2 nanoparticles is reported to prepare a photocatalytic nanocomposite for an enhanced visible‐light‐driven photodegradation of methylene blue (MB). CDs are prepared from citric acid (CA) and ethylenediamine (EDA) via hydrothermal treatment. Using MB as a model pollutant, it is observed that, under visible‐light irradiation, the nanocomposite presents an increment of the catalytic performance of 367% when compared to bare TiO2. This is achieved because the addition of CDs leads to increased visible‐light absorption and hinders the recombination of photogenerated charge carriers. Thus, CDs are capable of bridging some of the limitations posed by TiO2. Tests using reactive species scavengers indicate that the main active species involved in the photodegradation by the nanocomposites are superoxide radicals followed by hydroxyl radicals, which differs from bare TiO2. Lastly, a life cycle assessment (LCA) study shows that, when accounting for performance, the nanocomposites have lower relative environmental impacts than bare TiO2. In addition, the safety of the produced CDs is shown by in vitro assays. In summary, due to conjugation with CDs, a relevant increment in the catalytic performance of TiO2 is achieved; providing an important step toward the sustainable rational design of active visible‐light‐driven photocatalysts.

show abstract

Insight into the hybrid luminescence showed by carbon dots and molecular fluorophores in solution

Abstract: Prior to further purification, carbon dots interact with the fluorescent impurities of their synthesis to produce hybrid luminescence.

Cited by 50 publications

References 40 publications

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Evaluation of Different Bottom-up Routes for the Fabrication of Carbon Dots

Carbon Dots–TiO₂Nanocomposites for the Enhanced Visible‐Light Driven Photodegradation of Methylene Blue

Contact Info

Product

Resources

About

Insight into the hybrid luminescence showed by carbon dots and molecular fluorophores in solution

Abstract: Prior to further purification, carbon dots interact with the fluorescent impurities of their synthesis to produce hybrid luminescence.

Cited by 50 publications

References 40 publications

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Evaluation of Different Bottom-up Routes for the Fabrication of Carbon Dots

Carbon Dots–TiO2Nanocomposites for the Enhanced Visible‐Light Driven Photodegradation of Methylene Blue

Contact Info

Product

Resources

About

Carbon Dots–TiO₂Nanocomposites for the Enhanced Visible‐Light Driven Photodegradation of Methylene Blue