C60 Surface Research Articles

A theoretical investigation of the N2O + SO2 reaction on surfaces of P-doped C60 nanocage and Si-doped B30N30 nanocage

The mechanism of N2O reduction via SO2 on surfaces of P-doped C60 and Si-doped B30N30 by density functional theory were investigated. The P and Si adsorption energies on surface of C60 and B30N30 were calculated to be −287.5 and −312.1kcal/mol, respectively. The decomposition of C60-P-N2O and B30N30-Si-N2O and reduction of C60-P-O∗ and B30N30-Si-O∗ by SO2 molecule were investigated. The B30N30-Si-O∗ has lower activation energy and has more negative ΔGad rather than C60-P-O∗ and therefore the process of B30N30-Si-O∗+SO2→B30N30-Si+SO3 was spontaneous more than C60-P-O∗+SO2→C60-P+SO3 from thermodynamic view point. Results show that activation energies for B30N30-Si-O∗+N2O→B30N30-Si-O2+N2 and C60-P-O∗+N2O→C60-P-O2+N2 reactions were 33.23 and 35.82kcal/mol, respectively. The results show that P-doped C60 and Si-doped B30N30 can be observed as a real catalysts for the reduction of N2O.

Interactions of calcium with the external surfaces of fullerenes and endofullerenes doped with radioactive sodium iodide.

We report first-principles calculations carried out to analyze the adsorption of calcium on the outer surface of the fullerene C60, yielding [C60 + mCa]. Geometric optimization (GO) and molecular dynamics (MD) simulation were performed using the plane-wave pseudopotential method within the framework of density functional theory (DFT) and time-dependent DFT (TD-DFT) to investigate the configurations, the associated energies in the ground state, and the stabilities of fullerenes and endofullerenes doped with radioactive sodium iodide when they interact with calcium atoms on the outer fullerene surface (i.e., [nNa131I@C60 + mCa]). The reason for investigating these calcium-functionalized (endo)fullerene systems was to gauge their potential stability when used as vectors to deliver radioiodine to cancerous tissue in the human body. In the simulations, we found that the geometric limit on the number of calcium atoms that can be physisorbed on the outer surface of an empty fullerene while maintaining its structural stability is 28 calcium atoms, which also takes into account the proportional expansion of the fullerene as the number of absorbed calcium atoms increases. However, the stability of a fullerene system during calcium adsorption also strongly depends on whether any atoms or molecules are being encapsulated by the fullerene, as these encapsulated atoms/molecules can also interact with the fullerene and influence its stability. A Mulliken electronegativity analysis revealed that, when atoms inside and/or outside the fullerene donate charge (electrons) to the fullerene, the fullerene expands. The excess charge on the carbon atoms of the fullerene weakens some of the carbon-carbon bonds, potentially causing them to break, in which case the fullerene loses its ability to encapsulate molecules and releases them. Graphical Abstract DFT simulation of a endo fullerene doped with radioactive sodium iodide interacting with 28 calcium atoms in a geometric arrangement.

Density functional study of cyanogen (C2N2) sensing using OH functionalized fullerene (C60) and germanium-fullerene (Ge60)

Behavior of C2N2 adsorption on the surface of C60 and Ge60 was investigated by density functional theory calculation. The effects of OH functionalization on the adsorption of C2N2 gas via C60 and Ge60 surfaces were investigated. Results reveal that C60 and Ge60 were the most favorable cases toward the C2N2 adsorption, energetically. Results show that, Ead value of C2N2 on Ge60 surface were more negative than corresponding values of C60. Results reveal that, OH functionalization increase the absolute Ead values of C2N2 on studied fullerenes. These results show that, there are linearity dependencies between Ead and orbital energy values of studied fullerenes.

Coinage Metal Pyrazolates [(3,5-(CF3)2Pz)M]3 (M = Au, Ag, Cu) as Buckycatchers.

The synthesis and characterization of supramolecular assemblies {C60[M3]4}∞ consisting of C60 and coinage metal pyrazolates [M3] (i.e., [(3,5-(CF3)2Pz)M]3, where Pz = pyrazolate and M = Au, Ag, and Cu) are reported. {C60[Cu3]4}∞, {C60[Ag3]4}∞ and {C60[Au3]4}∞ form isomorphous crystals. The [M3] moieties adopt a concave conformation to complement the convex C60 surface. They exist as dimers of trimers (i.e., hexanuclear [M3]2 units) that are held together by three close M···M metallophilic interactions at 3.1580(17), 3.2046(7), and 3.2631(7) Å for copper, silver, and gold systems, respectively. The [M3]2 moieties surround each C60 in a tetrahedral fashion, while each [M3]2 is sandwiched by two C60 molecules to form a supramolecular 3D assembly.

The impacts of surface polarity on the solubility of nanoparticle.

In order to study the dependence of water solubility and hydration behavior of nanoparticles on their surface polarity, we designed polar nanoparticles with varying surface polarity by assigning atomic partial charge to the surface of C60. The water solubility of the nanoparticle is enhanced by several orders of magnitude after the introduction of surface polarity. Nevertheless, when the atomic partial charge grows beyond a certain value (qM), the solubility continuously decreases to the level of nonpolar nanoparticle. It should be noted that such qM is comparable with atomic partial charge of a variety of functional groups. The hydration behaviors of nanoparticles were then studied to investigate the non-monotonic dependence of solubility on the surface polarity. The interaction between the polar nanoparticle and the hydration water is stronger than the nonpolar counterpart, which should facilitate the dissolution of the nanoparticles. On the other hand, the surface polarity also reduces the interaction of hydration water with the other water molecules and enhances the interaction between the nanoparticles which may hinder their dispersion. Besides, the introduction of surface polarity disturbs and even rearranges the hydration structure of nonpolar nanoparticle. Interestingly, the polar nanoparticle with less ordered hydration structure tends to have higher water solubility.

Interface Controls of Lithium-Ion Batteries Electrodes through a Polymerized C60 Surface Coating

The increasing demand on high-energy and high-power lithium-ion batteries (LIBs) especially for electric vehicles application has driven the search on the high-capacity anode and cathode materials. For this purpose, SnO2-based anode materials (theoretical capacity of 900 mAhg-1) and LiCoO2 (theoretical capacity of 274 mAhg-1) have been intensively studied. However, the commercialization of SnO2 anode is still hindered due to the alloying mechanism which leads to severe volume expansion and eventually contributes to disintegrated material. While LiCoO2 has been used as commercial cathode materials, only half of its theoretical capacity (~140 mAhg-1) can be extracted at a cut-off voltage of 3.0-4.2 V. Although increasing cut-off voltage to 4.5 V would significantly boost the specific capacity, however severe side reactions between electrode and electrolyte and a structural phase transition from hexagonal to monoclinic causing structural damages of the electrode are the common issues occurred during the electrochemical cycle. Moreover, unstable solid-electrolyte interphase (SEI) layer on the surface of anode and cathode materials may worsen the situation leading to rapid capacity fading. Surface coating is considered as an appropriate approach in order to overcome the above-mentioned problems owing to its function to enhance interfacial kinetics and protect the host material underneath. Some metal oxides- and carbonaceous-based materials has been used as the coating materials for both anode and cathode materials. In this study, the plasma-polymerized C60 coatings both on the anode and cathode thin film electrodes are presented. The C60 coatings prepared by a radio-frequency plasma-assisted thermal evaporation are carried out on the surface of fluorine-doped SnO2 (C60@SnO2:F) anode and three-dimensional LiCoO2 (C60@3D-LiCoO2) cathode. The samples are characterized by SEM, XRD, TEM, EDX, XPS, ToF-SIMS and assembled into pouch-type and coin cells for anodes and cathodes, respectively. The results demonstrate the improved electrochemical performance of both C60-coated anode and cathode materials. For example, the C60@3D-LiCoO2 electrode delivers an initial discharge capacity of 175 mAhg-1 and maintains the capacity retention of 80% after 50 cycles at 0.1 C even with a high-voltage regime (~ 4.5 V). The C60@SnO2:F exhibits a high initial discharge capacity of 1255 mAhg-1 at 0.15 mAcm-2 and increases Coulombic efficiency of 98%. The improved electrochemical performance for C60@3D-LiCoO2 and C60@SnO2:F is attributed to the facts that the unique plasma-polymerized C60 thin film could provide (1) a mechanical strength to the host materials during repeated cycles directing to the material integrity, (2) a stabilized solid-electrolyte interphase (SEI) layer through a minimized oxygen functional groups in the electrode surface and (3) an enhanced interfacial conductivity leading to a facile Li ion diffusivity. The proposed strategy may open a broad range of application, not only for the two-mentioned electrodes, but also for other anode and cathodes materials of LIBs having similar concerns.

Study on the Conversion of Fullerenes to Fullerol Which May Be Used in Food Additives

In this research we choose TBAH as phase transfer and different density of H₂O₂ as oxidizing agent, which make fullerene’s c-c bond open. At the same time, in the high concentration of NaOH solution C60 can connect with hydroxyl. Then the products undergo the infrared spectroscopy test, UV-Vis test, fluorescence test and elemental analysis to sure the number of hydroxyl on the surface of C60. Finally, our next work is to use it into health care wine to improve people’s life quality.

(Invited) Concave Host Molecules Containing Phosphorus Atoms for Fullerenes

The recognition of fullerenes (C60 and its higher analogues) is one of the most intensive research subjects in supramolecular and host-guest chemistry. Bowl-type p-conjugated molecules, for example, corannulene or sumanene, are promising host molecules because their concave surfaces closely resemble fullerene segments and can fit precisely to the convex surface of C60. In particular, these molecules are attractive because of their potential to function as chiral hosts based on “bowl-chirality”. However, racemization easily underwent in many of chiral bowl-type molecules. We envision a strategy for the design of a chiral concave molecule using a phosphorus-doping method, which can play a crucial role in construction of the concave structure. We now report the synthesis of the chiral concave molecule by extension of the p-surface ofphosphorus-containing concave molecule. We synthesized the C 3-symmetric chiral concave mole-cule having a phosphorus atom at the center and resolved the enantiomers. The chiral concave structure was revealed by X-ray analysis. The concave molecule exhibited strong CD signals with a large anisotropy, the detail of which was confirmed by TD DFT calculation. In the co-crystal with C60, four molecules of enantiopure perfectly wrapped the surface of C60. MALDI-TOF mass and NMR spectra also supported the concave-convex interaction between the host molecule and C60. Furthermore, the observa-tion of the ICD signal of the guest fullerene indicates the transfer of the chiroptical properties of the host molecule to the guest. These results suggest that the chiral host is a component of a chiral self-assembled host for C60. The self-assembly of the concave molecules and the properties of the host-guest complex with fullerene will be presented. Figure 1

Spectroscopic observations of the displacement dynamics of physically adsorbed molecules—CO on C60

In this paper, we observed physically adsorbed CO molecules on C60 surface being displaced by impinging noble gas atoms (He, Ne, Ar, Kr), either through a dynamic displacement process or an exothermic replacement process, depending on their adsorption energies. This displacement mechanism could shift from one to the other depending on the surface coverage and temperature. Furthermore, rotational energy of the impinging molecules may also contribute to the dynamic displacement process by supplying additional energy.

Comparative tribological and corrosion resistance properties of epoxy composite coatings reinforced with functionalized fullerene C60 and graphene

Abstract This study investigated the effects of incorporation of two different shapes functionalization fullerene C60 (FC60) and functionalization graphene (FG), into the polymer matrix on the tribological and anti-corrosion performances of epoxy coating. The structural and morphological characterization was examined using Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. It was found that the functional groups had been grafted on the surface of C60 and G. The tribological and anti-corrosion results indicated that composite coatings showed a lower friction coefficient, wear traces area and higher anti-corrosion in comparison with neat epoxy, owing to the balance of reinforcement, lubrication and barrier properties of nanofillers and cracks generated by them, and optimal additive concentration of FC60 and FG both were 0.5 wt.%. Furthermore, this work opens up that FC60/EP coatings exhibited better tribological performance but worse corrosion resistance ability compared with FG/EP coatings due to the different shapes of nanofillers. Different tribological and anti-corrosion mechanisms were analyzed in details.

Temperature Evolution of Quasi-one-dimensional C60 Nanostructures on Rippled Graphene.

We report the preparation of novel quasi-one-dimensional (quasi-1D) C60 nanostructures on rippled graphene. Through careful control of the subtle balance between the linear periodic potential of rippled graphene and the C60 surface mobility, we demonstrate that C60 molecules can be arranged into a quasi-1D C60 chain structure with widths of two to three molecules. At a higher annealing temperature, the quasi-1D chain structure transitions to a more compact hexagonal close packed quasi-1D stripe structure. This first experimental realization of quasi-1D C60 structures on graphene may pave a way for fabricating new C60/graphene hybrid structures for future applications in electronics, spintronics and quantum information.

Trapping N5 rings and N3 chains on the outer surface of fullerene C60: a theoretical study.

The capture of N3-chains and N5-rings on the outer surface of C60 was studied using density functional calculations. For the neutral N5-ring, it was found that a N5-ring trapped by a C60 cage becomes more stable than an isolated N5-ring radical, and a C60-N5 compound with a C-N bond at an exohedral position of C60 is more stable than an isomer with the N5-ring encapsulated in C60. Such stability arises from the reduction in molecular strain energy, and charge transfer from C60 to N5. Dynamics calculations indicate that capture of the N5-ring on the outer surface of C60 is a barrierless process. Furthermore, the trapping sites of more N5-rings on the C60 were determined using condensed Fukui functions, where the N5-rings prefer to be trapped on the surface to form addition products across 6,6-junctions. Based on the optimized geometries of C60-(N5) n (n = 2, 6, 10), their chemical stabilities were found to be comparable with that of C60 in terms of the gap between the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals. Similar phenomena were found for an N3-chain wrapped on the surface of C60. However, the results of the average adsorption energies show that C60 can capture N5-rings more effectively than N3-chains.

Exohedral M-C60 and M2-C60 (M = Pt, Pd) systems as tunable-gap building blocks for nanoarchitecture and nanocatalysis.

Transition metal-fullerenes complexes with metal atoms bound on the external surface of C60 are promising building blocks for next-generation fuel cells and catalysts. Yet, at variance with endohedral M@C60, they have received a limited attention. By resorting to first principles simulations, we elucidate structural and electronic properties for the Pd-C60, Pt-C60, PtPd-C60, Pd2-C60, and Pt2-C60 complexes. The most stable structures feature the metal atom located above a high electron density site, namely, the π bond between two adjacent hexagons (π-66 bond). When two metal atoms are added, the most stable configuration is those in which metal atoms still stand on π-66 bonds but tends to clusterize. The electronic structure, rationalized in terms of localized Wannier functions, provides a clear picture of the underlying interactions responsible for the stability or instability of the complexes, showing a strict relationship between structure and electronic gap.

Theoretical Study on the Solvation of C60 Fullerene by Ionic Liquids II: DFT Analysis of the Interaction Mechanism.

As a continuation of our previous work (J. Phys. Chem. B, 2014, 118, 11330) on the solvation of C60 by ionic liquids (ILs) using Molecular Dynamic simulations, this paper reports a systematic density functional theory (DFT) analysis on the interaction mechanism between C60 and 24 different ionic liquids (belonging to the imidazolium, piperazinium, and cholinium groups). Properties such as binding energies, charge distributions, intermolecular interactions, or electronic structure were analyzed as a function of the selected ILs. The stronger IL-C60 interactions would be related with π-π stacking between the C60 surface and anions such as salycilate ([SA]). Likewise, the electronic structure analysis pointed to a well-defined relationship between the energetics of IL-C60 systems and IL features. Therefore, ILs with deep HOMO energies as well as weak interaction between both ions would be a priori good candidates for C60 solvation. Although only short-range interactions are studied in the framework of DFT, this work provides useful information for the rational design of ILs that could exhibit suitable features as C60 solvents.

Poly(vinyl pyrrolidone) Mediated Solubilization and Stabilization of Fullerene C60 in the Form of Nanofluid in an Alcoholic Medium

We report on the solubilization and stabilization of C60 molecules in presence of a macroscopic capping agent such as poly(vinyl pyrrolidone) PVP polymer in n-butanol using a sonochemical route. Augmentation in the absorbance value by nearly two times in the π → π* band in the C(sp2) electron transitions of C60 molecules at 328 nm in presence of PVP suggests an increase in the electron charge density on the surface interface via donor-acceptor interaction. A reasonably broad band feature observed in the π → π* transition at 435 nm in PVP moieties in a PVP-surface modified C60 sample indicates that PVP is cross-linking over the C60 surface in specific structure. Quenching of light emission in PVP molecules in n-butanol results from non bonding electrons (n) transfer from C˭O: (PVP) moieties to a C60 nanosurface in a C60:PVP charge transfer (CT) complex. Dynamic light scattering band measures two bands one at 32.0 nm and other one at 8.1 nm with average values of hydrodynamic diameter 9.2 nm and polydispersity index 0.35 apparently in two types of distinct structures. The zeta plot in the 4.63 μM C60 with PVP measures a zeta band with full width at half maximum ∼14.4 mV with average values of zetapotential ξ (−) 12.4 mV and surface conductivity of 0.074 mS/cm. The negative ξ-value describes that of O-atom of PVP molecules accumulate on the C60 surface via a chemisorptions process. Raman and Fourier transform infrared bands show that CT complex made in n-butanol presents a poor donation of the C˭O n-electrons from PVP moiety to the C60 molecules owing to adverse steric effect. High resolution transmission electron images in C60-PVP nanofluids illustrates a core-shell structure which consists of a C60 core covered by a shell of nearly 2.0 nm thickness of an amorphous PVP layer of a whitish contrast.

Efficient p-zinc phthalocyanine/n-fullerene organic bilayer electrode for molecular hydrogen evolution induced by the full visible-light energy

A photoelectrode featuring an organic p/n bilayer was used to generate H2 from H+, where n-type fullerene (C60) was used in combination with p-type zinc phthalocyanine (ZnPc). When a Pt catalyst was loaded on the surface of C60 in the organo-photoelectrode, a photocathodic current was successfully generated via H2 evolution at the Pt-coated C60 surface. On the basis of the results of action spectral measurements for photocurrent, the H2 evolution appeared to be induced over the entire visible-light wavelength range of <750 nm. In particular, the visible-light absorption of ZnPc/C60 bilayer efficiently contributed to carrier generation, consequently leading to the H2 evolution at the C60 surface via reducing power generated through a series of photophysical events within the bilayer.

Mechanism of Solubilizing Fullerene C60 in Presence of Poly(Vinyl pyrrolidone) Molecules in Water

In this article, a possible mechanism of solubilizing C60 molecules through poly (vinyl pyrrolidone) PVP is described in exploring its diverse biological, cosmetical, and medicinal activities. Markedly enhanced (∼ three times) absorbance, molar extinction coefficient, or oscillator strength in a π → π* band in the C(sp2) electron transitions of C60 molecules at 299 nm confers an effective surface adsorption of chromophoric groups of PVP molecules on the carbon surface. High resolution transmission electron and field emission scanning electron microscopic images in C60-PVP nanofluids clearly show adsorption of an amorphous PVP surface layer (35–37 nm thickness) on the C60 nanosurface. An intense dynamic light scattering band measuring an average hydrodynamic length of 306 nm attributes to PVP encapsulated C60 molecules. An average zetapotential (−) 17.8 mV at 6.5 pH describes PVP molecules aided accumulation of n-electrons on the C60 surface. Raman and Fourier transform infrared bands show distinctly enhanced intensity in the C ˭ O and C‒N stretching vibrations of lactam rings in presence of C60 molecule as a result of a charge transfer coupling of PVP functional groups with the C60 nanosurface. A nearly 11% decrease in emission band intensity in the n ← nπ* band of the PVP molecules at 393 nm upon addition of 4.0 µM C60 molecules exhibit n-electrons transfer from O-atom of pyrrolidone ring to electron deficient carbon nanosurface in surface modified C60 molecules.

Interaction of methyl radical (CH3) with C60 fullerene: Density functional theory (DFT) study

AbstractThe addition reaction of methyl radical (CH3) to fullerene (C60) surface has been investigated by means of density functional theory (DFT) method. The DFT calculation showed that the CH3 radical binds directly to the carbon atom of C60 and a strong C‐C single bond is formed. The binding energy of CH3 to C60was calculated to be 35.1 kcal/mol at the CAM‐B3LYP/6‐311G(d,p) level. The potential energy curve plotted as a function of a distance of CH3 from the C60 surface showed that the CH3 radical can approach to the carbon atom with very low activation barrier: the barrier height was calculated to be 2.8 kcal/mol. The electronic states of CH3‐C60 complex were discussed on the basis of theoretical results. (© 2015 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Icosahedral symmetry breaking: C(60) to C(84), C(108) and to related nanotubes.

This paper completes the series of three independent articles [Bodner et al. (2013). Acta Cryst. A69, 583-591, (2014), PLOS ONE, 10.1371/journal.pone.0084079] describing the breaking of icosahedral symmetry to subgroups generated by reflections in three-dimensional Euclidean space {\bb R}^3 as a mechanism of generating higher fullerenes from C60. The icosahedral symmetry of C60 can be seen as the junction of 17 orbits of a symmetric subgroup of order 4 of the icosahedral group of order 120. This subgroup is noted by A1 × A1, because it is isomorphic to the Weyl group of the semi-simple Lie algebra A1 × A1. Thirteen of the A1 × A1 orbits are rectangles and four are line segments. The orbits form a stack of parallel layers centered on the axis of C60 passing through the centers of two opposite edges between two hexagons on the surface of C60. These two edges are the only two line segment layers to appear on the surface shell. Among the 24 convex polytopes with shell formed by hexagons and 12 pentagons, having 84 vertices [Fowler & Manolopoulos (1992). Nature (London), 355, 428-430; Fowler & Manolopoulos (2007). An Atlas of Fullerenes. Dover Publications Inc.; Zhang et al. (1993). J. Chem. Phys. 98, 3095-3102], there are only two that can be identified with breaking of the H3 symmetry to A1 × A1. The remaining ones are just convex shells formed by regular hexagons and 12 pentagons without the involvement of the icosahedral symmetry.

Encapsulation of diatomic molecules in fullerene C60: implications for their main properties.

The endohedral complexes of diatomic guest molecules H2, N2, O2, F2, HF, CO, LiH, LiF, BN, and BeO with C60 have been characterized computationally by employing second-order Møller-Plesset (MP2) theory and its density-fitting local (DF-LMP2) variant. The interaction energies, equilibrium geometries, dipole moments and harmonic vibrational frequencies of these complexes have been systematically calculated. It was found that all guest molecules are stabilized inside the C60 cage, with the most pronounced stabilization effect (of about 50 kcal mol(-1)) observed for the polar covalent BeO and BN molecules. It is noteworthy that the normally short-lived BN molecule is the only guest molecule that was found to chemisorb on the inner surface of C60. When encapsulated, all guest molecules (except for BN) exhibit bond elongation (up to 0.07 Å) and, consequently, a red shift in vibrational stretching frequencies. In fact, the calculated vibrational properties of the H2@C60 complex agree well with those derived from experiment. The C60 geometry is not perturbed significantly upon encapsulation, but a subtle tendency to decrease the carbon-carbon bond alternation is observed. Polar guest molecules inside C60 are located at an off-center position and a significant decrease in their dipole moments upon encapsulation is observed. The importance of explicitly taking into account electron correlation effects, as well as full geometry relaxation, to yield a correct description of the complexes investigated is clearly demonstrated. The present results may serve as a guide for future attempts to synthesize such complexes employing the "molecular surgery" approach.