Interface and doping in carbon dots influence charge transfer and transport

Mishra, Leepsa; Behera, Ranjan Kumar; Mondal, Samrat; Kumar, Satish; Panigrahi, Aradhana; Sarangi, Manas Kumar

doi:10.1016/j.carbon.2021.03.026

Cited by 23 publications

(32 citation statements)

References 84 publications

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“…48−53 Recently, we have found that the electrostatic interactions between the micelle and CDs influence their ET ability. 12 We anticipate similar effects to be operating here with the highly negatively charged surface of the anionic RCDs interacting strongly with the cationic CTAB micellar surface by electrostatic attraction. Further, the addition of MD to the micellar surface leads to the solubilization of the molecule in the hydrophobic portion of the micelle, enhancing the ET process (Scheme 2a).…”

Section: Resultsmentioning

confidence: 60%

“…This is probably due to the solubilization of the organic molecule in the hydrophobic portion of the micelle bringing close contact between the substrate and borohydride. The confinement effect often results in uncommon photophysics and charge transfer phenomena. − Recently, we have found that the electrostatic interactions between the micelle and CDs influence their ET ability . We anticipate similar effects to be operating here with the highly negatively charged surface of the anionic RCDs interacting strongly with the cationic CTAB micellar surface by electrostatic attraction.…”

Section: Results and Discussionmentioning

confidence: 67%

“…Similarly, Mondal et al have explained that the doping in CDs with phosphate or boron significantly amplifies the ET efficiency between CDs and redox mediator, methyl viologen. Recently, we have reported the influence of doping and interface on the electron transfer and transport in CDs, revealing an alteration in the electron transfer rate from CDs to a quencher, menadione, in the micellar medium due to Coulombic interactions . Although easily synthesized and widely applied in different areas, the photophysical properties of the CDs are not easily understood.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we have reported the influence of doping and interface on the electron transfer and transport in CDs, revealing an alteration in the electron transfer rate from CDs to a quencher, menadione, in the micellar medium due to Coulombic interactions. 12 Although easily synthesized and widely applied in different areas, the photophysical properties of the CDs are not easily understood. Previous reports suggest that the CDs consist of an sp 2 passivation with many dangling bonds, including −COOH, −CO, −OH, etc.…”

Section: Introductionmentioning

confidence: 99%

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Surface Charge Alteration in Carbon Dots Governs the Interfacial Electron Transfer and Transport

et al. 2021

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Photoinduced electron transfer (PET) is a widely studied phenomenon in nanoscale carbon dots (CDs) due to the availability of free electrons on their surfaces. It is often treated as a molecular ruler to understand the interaction between nearby donor and acceptor pairs. The current report highlights the modulation of the electron transfer (ET) process in redox-treated CDs with an acceptor molecule, menadione (MD), when subjected to a microemulsion method. In the presence of cationic CTAB micellar heterogeneity, the ET kinetics get markedly altered due to the controlled diffusion dynamics of the reactant inside the microemulsion. In CTAB micellar media, reduced CDs (RCDs) show a higher ET efficiency with MD compared to the oxidized CDs (OCDs), owing to the substantial change in their surface charge and the stronger Coulombic interaction with the micellar interface. Moreover, the presence of CTAB moieties with RCDs greatly influences the local conductance and the electrical band gap at the single molecular level as noticed from current sensing atomic force microscopy measurements compared to OCDs. The current−voltage (I−V) measurements are observed to be nonlinear, revealing both direct and Fowler−Nordheim (FN) types of tunneling, while the presence of MD abruptly enhances the conductance linearly, curtailing the FN tunneling.

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Section: Resultsmentioning

confidence: 60%

Section: Results and Discussionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface Charge Alteration in Carbon Dots Governs the Interfacial Electron Transfer and Transport

et al. 2021

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“…Similar to semiconductor quantum dots, CDs show intriguing photophysical properties like size-dependent luminescence, excitation-dependent photoluminescence (EDPL), resistance to photobleaching, etc., which have been widely studied since their discovery . Another attractive property of CDs that has fueled recent research interest is the photoinduced electron transfer (ET) depending on the redox potential of the involved molecules. − Owing to sufficient π-conjugations, CDs have excess surface electrons that can readily participate in the CT process with adjacent molecules through ET and hydrogen atom transfer (HAT). Guldi et al have carried out some pioneering research on the CT on conjugated CDs and have shown their implications in artificial photosynthesis, catalysis, and organic electronics. − As CDs are often used for bioimaging, sensing, and tracking, photoinduced interactions with native biomolecules inside the cell environment will be of great interest.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Field Probes the Impact of the Ionic Micellar Interface on Photoinduced Charge-Transfer Kinetics of Carbon Dots

et al. 2021

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Carbon dots (CDs) are low-dimensional luminescent carbon materials with novel and tunable surface-dependent properties. Interfacial charge transfer is the fundamental principle mostly accountable for their extensive usage in catalysis and optoelectronics; however, this phenomenon remains mostly underexplored to date. Herein, we inspect the impact of cationic and anionic surfactants, encapsulation, and Coulombic interactions on the photoinduced interfacial charge-transfer kinetics between CDs and vitamin K3 (MQ). With a series of singlet and triplet state measurements, we have identified the transient intermediates, connoting the occurrence of excited-state electron transfer (ET) and hydrogen atom transfer (HAT) between the two. The strong electrostatic attraction between the cetyl trimethyl ammonium bromide micellar head groups and CDs enhances ET, while in the sodium dodecyl sulfate micellar medium, HAT is preferable. With an external magnetic field (MF) equivalent to the order of hyperfine interactions, we confirm the occurrence of both ET and HAT in triplet CDs and MQ and observe that their rates are significantly modulated not only by encapsulation but also by Coulombic interactions between the charged micellar interface and CDs. However, in the aqueous medium, the signature of charge-transfer products is very minimal even in the presence of the MF and is mostly indistinguishable within the measured time limit.

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Surface Modification Functionalized Carbon Dots

Wang,

Ai,

Song

et al. 2023

Chemistry A European J

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Carbon dots (CDs) smaller than 10 nm constitute a new type of fluorescent carbon‐based nanomaterial. They have attracted much attention owing to their unique structures and excellent photoelectric properties. Primitive CDs usually comprise carbon and oxygen and are synthesized in one step from various natural products or synthetic organic compounds, usually via microwave or hydrothermal methods. However, the uniformity of surface functional groups often make CDs lack the diversity of active sites required for specific applications. Therefore, the functionalization of CDs by specific groups is a powerful strategy for improving their photophysical and photochemical properties. This paper reviews surface modification strategies to overcome these shortcomings. Functionalizing CDs using covalent or non‐covalent modification can give them unique properties and broaden their applicability.

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Interface and doping in carbon dots influence charge transfer and transport

Cited by 23 publications

References 84 publications

Surface Charge Alteration in Carbon Dots Governs the Interfacial Electron Transfer and Transport

Surface Charge Alteration in Carbon Dots Governs the Interfacial Electron Transfer and Transport

Magnetic Field Probes the Impact of the Ionic Micellar Interface on Photoinduced Charge-Transfer Kinetics of Carbon Dots

Surface Modification Functionalized Carbon Dots

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