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Schematic illustration of exfoliation of few-layer graphene with CT to yield monolayer graphene-CT composites27.
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Charge-transfer between electron–donor and –acceptor molecules is a widely studied subject of great chemical interest. Some of the charge-transfer compounds in solid state exhibit novel electronic properties. In the last two to three years, occurrence of molecular charge-transfer involving single-walled carbon nanotubes (SWNTs) and graphene has bee...
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Despite widely reported fluorescence sensors for cations, direct detection of anions is nevertheless still rare. In this work, ionic liquid-functionalized fluorescent carbon nanoribbons (IL-CNRs) are one-step synthesized and serve as the fluorescent probes for direct and sensitive detection of sulfide ions (S²⁻). The IL-CNRs are synthesized based o...
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... The charge transfer process between nitrobenzene and graphene was confirmed by a shift of the G-band from 1585.2 to 1594.64 cm À 1 as confirmed by Rao's report. [96] Rao and coworkers demonstrated that the functionalization of graphene by an electron-withdrawing group or doping with different heteroatoms stiffens the G-band in the Raman spectrum which shifts it towards higher wavenumbers. The I D /I G value is also indicative of the defect levels on the carbon framework so an increase in that intensity ratio on the nitrobenzene graphene (NB-graphene) as shown in Figure 14(b) occurs due to the transformation of the sp 2 carbon to sp 3 carbon due to covalent functionalization of graphene with nitrobenzene. ...
Due to their low cost, accessibility of resources, and improved stability and durability, carbon‐based nanomaterials have attracted significant attention as cathode materials for oxygen reduction reactions. These materials also exhibit intrinsic physical and electrochemical features. However, their potential for use in fuel cells is constrained by low ORR activity and slow kinetics. Carbon nanomaterials can be functionalized and doped with heteroatoms to change their morphologies and generate a large number of oxygen reduction active sites to lessen the problems. Doping the carbon lattice with heteroatoms like N, S, and P and functionalizing the carbon structure with −OCH 3 , −F, −COO ⁻ , −O ⁻ are two of these modifications that can change specific properties of the carbon nanomaterials like expanding interlayer distance, producing a large number of active sites, and enhancing oxygen reduction activity. When compared to pristine carbon‐based nanomaterials, these doped and functionalized carbon nanomaterials, including their composites, exhibit accelerated rate performance, outstanding stability, and higher methanol tolerance. This article summarizes the most recent developments in heteroatom‐doped and functionalized carbon‐based nanomaterials, covering different synthesis approaches, characterization methods, electrochemical performance, and oxygen reduction reaction mechanisms. As cathode materials for fuel cell technologies, the significance of heteroatom co‐doping and transition metal heteroatom co‐doping is also underlined.
... Since the advent of ultra-fast laser pulses, charge transfer collisions have also been used to probe fundamental quantum dynamics as these reactions are heavily dependent on the properties of the electronic wave function [7]. Recently, charge transfer research has expanded to more complex systems such as large molecules, nano-size clusters, and condense matter materials [8][9][10][11]. Fullerenes have become a popular molecule to study due to their high degree of symmetry [12] and potential technological applications [9,13,14]. ...
... Recently, charge transfer research has expanded to more complex systems such as large molecules, nano-size clusters, and condense matter materials [8][9][10][11]. Fullerenes have become a popular molecule to study due to their high degree of symmetry [12] and potential technological applications [9,13,14]. ...
We present a theoretical description of resonant charge transfer in collisions of nano-particles, specifically for $C_{60} + C_{60}^+$ collisions. We predict that transient bonds between colliding fullerenes can significantly extend the interaction time, allowing for a greater probability of charge transfer. In our model, the dumbbell-shaped $(C_{60}-C_{60})^+$ quasi-molecule, that is temporarily formed during the collision, is described as a dynamic system of 120 zero-range potentials. Using this model, we calculate the exchange interaction between colliding fullerenes and subsequently determine the corresponding charge transfer cross sections at different collision velocities. Our results have been verified with data obtained from quantum molecular dynamics simulations of the fullerene collisions. The presented theoretical model provides a description of the experimental data on the $C_{60} + C_{60}^+ $ resonant charge transfer collision through the inclusion of the temporary formation of dumbbell-shaped fullerene molecules at low collision velocities.
... In addition, it is also worth saying that the charge transfer of graphene-based materials can also be driven by the number of carbon layers. In general, charge-transfer tends to be more efficient for thinner graphenic layers 29 . Subsequent control measurements of the surface potential with KPFM under Ar atmosphere were performed, where the samples were previously dried under Ar flux. ...
At the time when pathogens are developing robust resistance to antibiotics, the demand for implant surfaces with microbe-killing capabilities has significantly risen. A profound understanding of the underlying mechanisms is...
... Hence, we must consider noise impact on 2D materials applications and investigate the mechanisms of flicker noise generation to reduce its effects in some cases (circuit design) and to exploits its potentialities in some other cases (advanced sensors design). We underline that these materials offer new opportunities for fundamentals of noise mechanisms studies because we can make the film of thickness up to a single atom layer and modify concentrations of charge transfer 153,154 so that it will be possible to associate the noise produced to the structure of the device in a more detailed way. However, since most of these materials have only recently become available, the detailed mechanisms of noise generation are still not fully recognized. ...
Electronic noise has its roots in the fundamental physical interactions between matter and charged particles, carrying information about the phenomena that occur at the microscopic level. Therefore, Low-Frequency Noise Measurements (LFNM) are a well-established technique for the characterization of electron devices and materials and, compared to other techniques, they offer the advantage of being non-destructive and of providing a more detailed view of what happens in the matter during the manifestation of physical or chemical phenomena. For this reason, LFNM acquire particular importance in the modern technological era in which the introduction of new advanced materials requires in-depth and thorough characterization of the conduction phenomena. LFNM also find application in the field of sensors, as they allow to obtain more selective sensing systems even starting from conventional sensors. Performing meaningful noise measurements, however, requires that the background noise introduced by the measurement chain be much smaller than the noise to be detected and the instrumentation available on the market does not always meet the specifications required for reaching the ultimate sensitivity. Researchers willing to perform LFNM must often resort to the design of dedicated instrumentation in their own laboratories, but their cultural background does not necessarily include the ability to design, build, and test dedicated low noise instrumentation. In this review, we have tried to provide as much theoretical and practical guidelines as possible, so that even researchers with a limited background in electronic engineering can find useful information in developing or customizing low noise instrumentation.
... In S1, this band is not defined, which has been associated with the presence of amorphous carbon [69]. The observed 2D position for S2 (2667 cm − 1 ) to the published value for graphite (2697 cm − 1 ) could be associated with fewer layers of carbon material [70] and hole doping structure [71]. The 2D position for S2-Ox (2679 cm − 1 ) is consistent with higher nitrogen doping [69]. ...
... The 2D position for S2-Ox (2679 cm − 1 ) is consistent with higher nitrogen doping [69]. Finally, the G band position to lower wavenumber from 1592 cm − 1 (S1) to 1575 cm − 1 (S2) then to 1573 cm − 1 (S2-Ox) is associated with the presence of sp 2 disordered carbon domains, usually related to foreign atoms in the graphite structure [71], in close relation to the proposed increase in nitrogen doping, discussed with more detail in the infrared and XPS spectroscopy sections. ...
... This suggests that among the two FLG materials, FLG 10 presents a higher number of defects. Furthermore, compared to pristine FLG 10 , 2FLG 10 / GCN presents a decrease in the intensity ratio, probably owing to new sp 2 regions due to the interactions with carbon nitride, along with an upper-shift (2 cm À1 ) and a down-shift (3 cm À1 ) of the D and G bands, respectively, suggesting possible charge transfer interactions between both materials [78,79]. To further validate the few-layer structure, G and 2D peaks in Raman spectra were used to estimate the number of graphene layers. ...
Few-layer graphene (FLG, 2–7 nm thickness) prepared by catalytic chemical vapour deposition (c-CVD), and bulk graphitic carbon nitride (g-C3N4; GCN) were assembled to develop novel 2D/2D xFLGy/GCN heterostructures. The impact of FLG loading and morphology on the activity of GCN has been evaluated towards H2 generation from water splitting under visible-LED irradiation. The heterostructures, characterised by UV–vis DRS, photoluminescence, EPR, Raman, AFM, XRD, XPS, SEM/TEM/STEM and photocurrent, present strong interfacial interaction and show higher photocatalytic activity than pure GCN. The best performing material, 2FLG10/GCN, generated 1274 g−1 h−1 of H2, i.e., 4-times higher than pure GCN. The improved photoactivity was ascribed to a synergistic effect between GCN and FLG, owing to: i) efficient charge separation of photoinduced electron-hole pairs through electron transfer from GCN to FLG, ii) increased surface area, and iii) enhanced visible light absorption. Moreover, the best performing composite presents high stability after four successive cycles with no significant change in its activity.
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... Current development of experimental and theoretical investigations includes investigations of charge transfer collisions with more complex targets, such as molecules, nano-size clusters and condense matter materials [13][14][15][16] . Interest in these processes is due to applications in bio-medical fields and nanoscience. ...
A semi-classical model describing the charge transfer collisions of $C_{60}$ fullerene with different slow ions has been developed to explain available experimental data. This data reveals multiple Breit-Wigner like peaks in the cross sections, with subsequent peaks of reactive cross sections decreasing in magnitude. Calculations of the charge transfer probabilities and cross sections for quasi-resonant and reactive collisions have been performed using semi-empirical potentials of interaction between fullerenes and ion projectiles. All computations have been carried out with realistic wave functions for $C_{60}$'s valence electrons derived from the simplified jellium model. The quality of these electron wave functions have been successfully verified by comparing theoretical calculations and experimental data on the small angle cross sections of resonant $C_{60}+ C_{60}^+$ collisions. Using the semi-empirical potentials to describe resonant scattering phenomena in $C_{60}$ collisions with ions and Landau-Zener charge transfer theory, we calculated theoretical cross sections for various $C_{60}$ charge transfer and fragmentation reactions which agree with experiments.
... In S1, this band is not defined, which has been associated with the presence of amorphous carbon [69]. The observed 2D position for S2 (2667 cm − 1 ) to the published value for graphite (2697 cm − 1 ) could be associated with fewer layers of carbon material [70] and hole doping structure [71]. The 2D position for S2-Ox (2679 cm − 1 ) is consistent with higher nitrogen doping [69]. ...
... The 2D position for S2-Ox (2679 cm − 1 ) is consistent with higher nitrogen doping [69]. Finally, the G band position to lower wavenumber from 1592 cm − 1 (S1) to 1575 cm − 1 (S2) then to 1573 cm − 1 (S2-Ox) is associated with the presence of sp 2 disordered carbon domains, usually related to foreign atoms in the graphite structure [71], in close relation to the proposed increase in nitrogen doping, discussed with more detail in the infrared and XPS spectroscopy sections. ...
Sponge-type nitrogen-doped multiwall carbon nanotubes (N-MWCNTs), synthesized via an aerosol-assisted catalytic chemical vapor deposition (AACCVD) method, were extensively studied. A ball-milled and oxidized red-leptosol (RL) was used as the catalyst precursor, and benzylamine worked as a carbon and nitrogen source. The ball-milled and oxidized RL increased their contact area and purity for the N-MWCNT synthesis. X-ray diffraction characterization revealed that raw RL contained kaolinite, quartz, graphite, hematite, and goethite. According to the electron microscopy analysis, the N-MWCNTs exhibited exotic morphologies and microstructures. The high-resolution X-ray photoelectron spectroscopy showed that the as-grown N-MWCNTs contained pyrrolic and pyridinic nitrogen species. The cyclic voltammetry studies demonstrated that the redox processes in the N-MWCNTs in 0.1 M H2SO4 were dominated by the carboxyl, pyridinic, and pyrrolic groups. Using the natural RL as a catalyst precursor in AACCVD led to a large yield of N-MWCNTs mixed with different minerals, causing the observed morphologies and influencing the electrochemical behavior, which is of interest in energy-storage and sensing applications.
... Other factors like uniaxial mechanical strain in SWCNTs or alteration in the structural integrity of sp 2 -hybridized C atoms causes shifting of G-band. 6,40,41 This is also due to the decrease in the tube−tube interaction by increasing the intertubular spaces between individual nanotubes when ZnO is loaded. 18 The D-band or distortion band of SWCNTs gives information regarding the presence of defects, dislocations, nanotube ends, and chemical functionalization. ...
Noncovalent functionalization of single-walled carbon nanotubes (SWCNT) by semiconducting oxides is a majorly sought technique to retain individual properties while creating a synergetic effect for an efficient heterostructure charge transfer. Three types of electronically and optically different SWCNTs: metallic (m), semiconducting (s), and pristine (p) are functionalized by ZnO using a facile sonication method. The physicochemical and morphological properties of the ZnO-functionalized SWCNTs, m-SWCNT+ZnO, s-SWCNT+ZnO, and p-SWCNT+ZnO, are analyzed by advanced characterization techniques. Evidence of charge transfer between SWCNT and ZnO is observed with an increase in charge carrier lifetime from 3.31 ns (ZnO) to 4.76 ns (s-SWCNT+ZnO). To investigate the optimum interaction between SWCNTs and ZnO, critical coagulation concentrations (CCC) are determined using UV-vis absorption spectroscopy for m-SWCNT, s-SWCNT, and p-SWCNT using different molar concentrations of ZnO as the coagulant. The interaction and coagulation mechanisms are described by the modified DLVO theory. Due to the variation in dielectric values and electronic properties of SWCNTs, the CCC values obtained have differed: m-SWCNT (1.9 × 10-4), s-SWCNT (3.4 × 10-4), and p-SWCNT (2 × 10-4). An additional analysis of the aggregates and supernatants of the CCC experiments is also shown to give an insight into the interaction and coagulation processes, explaining the absence of influence exerted by sedimentation and centrifugation.
... 14 Also we don't exclude the charge exchange between nanotubes and electron-acceptor TMPyP4 that must lead to the some blue shift of the G + band relative to SWNTs:DNA. 21 Figure 4(a) shows the dependence of the G + band intensity extracted from Raman spectra presented in Fig. 2 on the polarization angle in the VV geometry. The intensity of the G + band shows a maximum at around θ ≈ 0°when E is parallel to the nanotube axis and gradually decreases down to about 90°at perpendicular orientation of E to the stretching direction of the films. ...
We present the polarized Raman studies and light absorption study of nanoassemblies of DNA-wrapped single-walled carbon nanotubes (SWNTs) incorporated into the gelatin film. Nanoassemblies are formed in aqueous suspension with SWNTs:DNA by positively charged 5,10,15,20-tetrakis-(N-methyl-4-pyridyl) porphyrin (TMPyP4). The gelatin film with embedded nanoassemblies was exposed to a mechanical stretching to about 300% tensile strain for making an alignment along a chosen direction. The analysis of the absorption spectra taken along and normal to the stretching direction revealed the strong polarized dependence. The polarized Raman spectra of the stretched gelatin film showed the angular dependence of the integrated intensity of tangential mode of SWNTs that allowed to estimate the alignment degree. It showed that about 60% of the SWNT nanoassemblies are aligned in the range of ± 15° to the direction of the stretching. The addition of the porphyrin derivative does not impede the orientation of the SWNTs:DNA nanohybrids along the stretching direction. The performed studies of embedded SWNTs:DNA:TMPyP4 nanoassemblies in the flexible gelatin film are intended to show the simple method for obtaining the controlled ordered biocompatible nanotube networks functionalized by the porphyrin derivatives inside a polymer matrix.
