An emerging class of heterostructures with unprecedented (photo)electrocatalytic behavior, involving the combination of fullerenes and low‐dimensional (LD) nanohybrids, is currently expanding the ...field of energy materials. The unique physical and chemical properties of fullerenes have offered new opportunities to tailor both the electronic structures and the catalytic activities of the nanohybrid structures. Here, we comprehensively review the synthetic approaches to prepare fullerene‐based hybrids with LD (0D, 1D, and 2D) materials in addition to their resulting structural and catalytic properties. Recent advances in the design of fullerene‐based LD nanomaterials for (photo)electrocatalytic applications are emphasized. The fundamental relationship between the electronic structures and the catalytic functions of the heterostructures, including the role of the fullerenes, is addressed to provide an in‐depth understanding of these emerging materials at the molecular level.
This Review discusses synthetic approaches to fullerene‐based hybrids with low‐dimensional (LD) materials and their properties. Recent advances in the design of fullerene‐based LD nanomaterials for (photo)electrocatalytic applications are emphasized. The relationship between the electronic structures and the catalytic functions of the heterostructures is addressed to provide an understanding of these emerging materials at the molecular level.
Abstract
The electrocatalytic hydrogen evolution reaction (HER) is one of the most studied and promising processes for hydrogen fuel generation. Single-atom catalysts have been shown to exhibit ...ultra-high HER catalytic activity, but the harsh preparation conditions and the low single-atom loading hinder their practical applications. Furthermore, promoting hydrogen evolution reaction kinetics, especially in alkaline electrolytes, remains as an important challenge. Herein, Pt/C
60
catalysts with high-loading, high-dispersion single-atomic platinum anchored on C
60
are achieved through a room-temperature synthetic strategy. Pt/C
60
-2 exhibits high HER catalytic performance with a low overpotential (η
10
) of 25 mV at 10 mA cm
−2
. Density functional theory calculations reveal that the Pt-C
60
polymeric structures in Pt/C
60
-2 favors water adsorption, and the shell-like charge redistribution around the Pt-bonding region induced by the curved surfaces of two adjacent C
60
facilitates the desorption of hydrogen, thus favoring fast reaction kinetics for hydrogen evolution.
Ever since the first experimental evidence of the existence of endohedral metallofullerenes (EMFs) was obtained, the search for carbon cages with encapsulated metals and small molecules has become a ...very active field of research. EMFs exhibit unique electronic and structural features, with potential applications in many fields. Furthermore, functionalized EMFs offer additional potential applications because of their higher solubility and their ease of characterization by X-ray crystallography and other techniques. Herein we review the general field of EMFs, particularly of functionalized EMFs. We also address their structures and their (electrochemical) properties, as well as applications of these fascinating compounds.
The inflammatory effects of carbon nanoparticles (NPs) are highly disputed. Here it is demonstrated that endotoxin‐free preparations of raw carbon nanotubes (CNTs) are very limited in their capacity ...to promote inflammatory responses in vitro, as well as in vivo. Upon purification and selective oxidation of raw CNTs, a higher dispersibility is achieved in physiological solutions, but this process also enhances their inflammatory activity. In synergy with toll‐like receptor (TLR) ligands, CNTs promote NLRP3 inflammasome activation and it is shown for the first time that this property extends to spherical carbon nano‐onions (CNOs) of 6 nm in size. In contrast, the benzoic acid functionalization of purified CNTs and CNOs leads to significantly attenuated inflammatory properties. This is evidenced by a reduced secretion of the inflammatory cytokine IL‐1β, and a pronounced decrease in the recruitment of neutrophils and monocytes following injection into mice. Collectively, these results reveal that the inflammatory properties of carbon NPs are highly dependent on their physicochemical characteristics and crucially, that chemical surface functionalization allows significant moderation of these properties.
The inflammatory properties of carbon nanoparticles are regarded as a major roadblock in their use for biomedical applications. A simple and reproducible strategy is described to address this issue using a novel purification process combined with surface chemical functionalization. This is also the first report that single walled carbon nanotubes and carbon nano‐onions have the ability to activate the NLRP3 inflammasome.
Carbon‐based nanomaterials have attracted much interest during the last decade for biomedical applications. Multimodal imaging probes based on carbon nano‐onions (CNOs) have emerged as a platform for ...bioimaging because of their cell‐penetration properties and minimal systemic toxicity. Here, we describe the covalent functionalization of CNOs with fluorescein and folic acid moieties for both imaging and targeting cancer cells. The modified CNOs display high brightness and photostability in aqueous solutions and their selective and rapid uptake in two different cancer cell lines without significant cytotoxicity was demonstrated. The localization of the functionalized CNOs in late‐endosomes cell compartments was revealed by a correlative approach with confocal and transmission electron microscopy. Understanding the biological response of functionalized CNOs with the capability to target cancer cells and localize the nanoparticles in the cellular environment, will pave the way for the development of a new generation of imaging probes for future biomedical studies.
Class onion: Surface functionalization of small multi‐shell fullerenes (diameter of 5 nm) with imaging and cell recognition capabilities was accomplished. This integrated system allows the targeting of cancer cells and the detailed analysis of its pathway. The localization of the imaging probe in the cell environment was analysed by correlation of confocal and electron microscopy (see figure).
Fullerene (C60) and multilayer graphene hybrid devices were fabricated using electrophoretic deposition, where the C60 clusters are electrically charged upon the application of an external bias in a ...polar solvent, acetonitrile, mixed with toluene, which facilitates their deposition on the graphene membranes. Raman spectroscopy unveiled the unique vibrational fingerprints associated with the A2g mode of the C60 molecules at ∼1453 cm–1, while blue shifts of ∼6 and ∼17 cm–1 were also attributed to the G- and 2D-bands of the hybrids relative to bare graphene, suggestive of p-doped graphene. The intensity ratio of the G- and the 2D-bands I 2D/I G (hybrid) dropped to ∼0.18 from ∼0.3 (bare graphene), and this reduction in I 2D/I G is also a signature of hole-doped graphene, consistent with the relatively strong electron accepting nature of C60. The electronic conductance of the two-terminal hybrid devices increased relative to bare graphene at room temperature which was attributed to the increased carrier density, and temperature-dependent electronic transport measurements were also conducted from ambient down to ∼5.8 K. Additionally, a low energy shift in the Fermi level, E F ≈ 140 meV, was calculated for the hybrids. When the hybrid devices were irradiated with a broadband white light source and a tunable laser source (with a wavelength λ ranging from ∼400–1100 nm), a strong photoresponse was evident, in contrast to the bare graphene devices which appeared unresponsive. The responsivity R of the hybrids was measured to be ∼109 A/W at λ ≈ 400 nm and ∼298 K, while the detectivity and external quantum efficiency were also exceptional, ∼1015 jones and ∼109%, respectively, at ∼1 V and a light power density of ∼3 mW/cm2. The R values are ∼10 times higher compared to other hybrid devices derived from graphene reported previously, such as quantum dot-graphene and few-layer MoS2–graphene heterostructures. The strong photoresponse of the C60–graphene hybrids reported here is attributed to the doping enhancement arising in graphene upon the adsorption of C60. This work demonstrates the exceptional potential of such hybrid nanocarbon-based structures for optoelectronics.
Abstract
Actinide diatomic molecules are ideal models to study elusive actinide multiple bonds, but most of these diatomic molecules have so far only been studied in solid inert gas matrices. Herein, ...we report a charged U≡N diatomic species captured in fullerene cages and stabilized by the U-fullerene coordination interaction. Two diatomic clusterfullerenes, viz. UN@
C
s
(6)-C
82
and UN@
C
2
(5)-C
82
, were successfully synthesized and characterized. Crystallographic analysis reveals U-N bond lengths of 1.760(7) and 1.760(20) Å in UN@
C
s
(6)-C
82
and UN@
C
2
(5)-C
82
. Moreover, U≡N was found to be immobilized and coordinated to the fullerene cages at 100 K but it rotates inside the cage at 273 K. Quantum-chemical calculations show a (UN)
2+
@(C
82
)
2−
electronic structure with formal +5 oxidation state (f
1
) of U and unambiguously demonstrate the presence of a U≡N bond in the clusterfullerenes. This study constitutes an approach to stabilize fundamentally important actinide multiply bonded species.
Supramolecular nanocapsule 1⋅(BArF)8 is able to sequentially and selectively entrap recently discovered U2@C80 and unprecedented Sc2CU@C80, simply by soaking crystals of 1⋅(BArF)8 in a toluene ...solution of arc‐produced soot. These species, selectively and stepwise absorbed by 1⋅(BArF)8, are easily released, obtaining highly pure fractions of U2@C80 and Sc2CU@C80 in one step. Sc2CU@C80 represents the first example of a mixed metal actinide‐based endohedral metallofullerene (EMF). Remarkably, the host–guest studies revealed that 1⋅(BArF)8 is able to discriminate EMFs with the same carbon cage but with different encapsulated cluster and computational studies provide support for these observations.
In U go: Supramolecular nanocapsule 1⋅(BArF)8 is able to sequentially and selectively entrap the endohedral metallofullerenes U2@C80 and Sc2CU@C80, simply by soaking crystals of 1⋅(BArF)8 in a toluene solution of arc‐produced soot. The endohedral metallofullerenes are easily released, giving highly pure fractions of U2@C80 and Sc2CU@C80 in one step.
A regiospecific bis-adduct of C70 with anthracene was prepared with unusually high yield (68%) by the Diels-Alder reaction in the absence of solvent (melt). The structure of the bis-adduct was an ...unexpected 12 o'clock isomer, as determined by single crystal X-ray diffraction, thermal gravimetric analysis (TGA) and spectroscopy.
A series of π‐extended distyryl‐substituted boron dipyrromethene (BODIPY) derivatives with intense far‐red/near‐infrared (NIR) fluorescence was synthesized and characterized, with a view to enhance ...the dye’s performance for fluorescence labeling. An enhanced brightness was achieved by the introduction of two methyl substituents in the meso positions on the phenyl group of the BODIPY molecule; these substituents resulted in increased structural rigidity. Solid‐state fluorescence was observed for one of the distyryl‐substituted BODIPY derivatives. The introduction of a terminal bromo substituent allows for the subsequent immobilization of the BODIPY fluorophore on the surface of carbon nano‐onions (CNOs), which leads to potential imaging agents for biological and biomedical applications. The far‐red/NIR‐fluorescent CNO nanoparticles were characterized by absorption, fluorescence, and Raman spectroscopies, as well as by thermogravimetric analysis, dynamic light scattering, high‐resolution transmission electron microscopy, and confocal microscopy.
Know your onions: A series of bright fluorescent boron dipyrromethene (BODIPY) dyes was synthesized and characterized (see figure); single crystals of one fluorophore reveal solid‐state fluorescence. Subsequently, the far‐red/near‐infrared‐fluorescent BODIPY dye was attached to carbon nano‐onions, to give a red fluorescent carbon nanomaterial.
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