Alkali-metal-induced enhancement of hydrogen adsorption in C60 fullerene: an ab Initio study

Density functional study of physisorption of H2 molecules on scandium and yttrium decorated C20 fullerene: prospect for hydrogen storage

CONTEXT

Hydrogen storage in porous nanostructured compounds have recently attracted a lot of attention due to the fact that the underlying adsorption mechanism and thermodynamics provide suitable platform for room temperature adsorption and desorption of H2 molecules. This work reports the findings of a study on the reversible hydrogen storage capacities of Sc and Y decorated C20 fullerene, conducted using dispersion-corrected density functional theory (DFT) calculation. The transition metal (TM) atoms, such as Sc and Y, are identified to attach to the C-C bridge position of the C20 fullerene through non-covalent closed-shell interactions. This suggests that the interaction between the TM atoms and the fullerene occurs via weak van der Waals forces rather than stronger covalent bonds. The thermodynamic stability of the decorated fullerene structures is assessed using different reactivity descriptors. Each Sc and Y atom attached to the C20 fullerene is capable of absorbing maximum of 6 and 7 numbers of hydrogen molecules, respectively. This results in practical gravimetric densities of up to 4.0 wt% and 4.04 wt% at a temperature of 300 K and a pressure of 60 bar. These findings highlight the significant hydrogen storage capacities of the decorated fullerene structures, indicating their potential for practical use in hydrogen storage systems. The average adsorption energy of H2 molecules is found lying in the range of 0.332-0.276 eV implying the adsorption process to be physisorptive. Overall, the study provides valuable insights into the hydrogen storage capabilities of Sc and Y decorated C20 fullerene complexes, offering a promising avenue for the development of efficient and reversible hydrogen storage materials for clean energy applications.

METHODS

Geometry optimization and other electronic structure calculations was performed by Gaussian 09 software using density functional theory (DFT) with the B3LYP-D3 and M06-2X functionals and the basis set 6-311 + G(d,p). The dispersion-corrected and hybrid meta-exchange correlation functionals were employed because of their accuracy in describing non-covalent interactions, rendering them appropriate for investigating hydrogen adsorption on surfaces.

Adsorption of molecular hydrogen (H2) on a fullerene (C60) surface: insights from density functional theory and molecular dynamics simulation

Understanding the adsorption behavior of molecular hydrogen (H2) on solid surfaces is essential for a variety of technological applications, including hydrogen storage and catalysis. We examined the adsorption of H2 (∼2800 configurations) molecules on the surface of fullerene (C60) using a combined approach of density functional theory (DFT) and molecular dynamics (MD) simulations with an improved Lennard-Jones (ILJ) potential force field. First, we determined the adsorption energies and geometries of H2 on the C60 surface using DFT calculations. Calculations of the electronic structure help elucidate underlying mechanisms administrating the adsorption process by revealing how H2 molecules interact with the C60 surface. In addition, molecular dynamics simulations were performed to examine the dynamic behavior of H2 molecules on the C60 surface. We accurately depicted the intermolecular interactions between H2 and C60, as well as the collective behavior of adsorbed H2 molecules, using an ILJ potential force field. Our findings indicate that H2 molecules exhibit robust physisorption on the C60 surface, forming stable adsorption structures with favorable adsorption energies. Calculated adsorption energies and binding sites are useful for designing efficient hydrogen storage materials and comprehending the nature of hydrogen's interactions with carbon-based nanostructures. This research provides a comprehensive understanding of H2 adsorption on the C60 surface by combining the theoretical framework of DFT calculations with the dynamical perspective of MD simulations. The outcomes of the present research provide new insights into the fields of hydrogen storage and carbon-based nanomaterials, facilitating the development of efficient hydrogen storage systems and advancing the use of molecular hydrogen in a variety of applications.

Multifacets of Fullerene-Metal Clusters: From Fundamental to Application

ConspectusBuckminsterfullerene, C60, was discovered through a prominent mass peak containing 60 atoms produced from laser vaporization of graphite, driven by Kroto's interest in understanding the formation mechanisms of carbon-containing molecules in space. Inspired by the geodesic dome-shaped architecture designed by Richard Buckminster Fuller, after whom the particle was named, C60 was found to have a football-shaped structure comprising 20 hexagons and 12 pentagons. It sparked worldwide interest in understanding this new carbon allotrope, resulting in the awarding of the Noble Prize in Chemistry to Smalley, Kroto, and Curl in 1996.Intrinsically, C60 is an exceptional species because of its high stability and electron-accepting ability and its structural tunability by decorating or substituting either on its exterior surface or interior hollow cavity. For example, metal-decorated fullerene complexes have found important applications ranging from superconductivity, nanoscale electronic devices, and organic photovoltaic cells to catalysis and biomedicine. Compared to the large body of studies on atoms and molecules encapsulated by C60, studies on the exteriorly modified fullerenes, i.e., exohedral fullerenes, are scarcer. Surprisingly, to date, uncertainty exists about a fundamental question: what is the preferable exterior binding site of different kinds of single atoms on the C60 surface?In recent years, we have developed an experimental protocol to synthesize the desired fullerene-metal clusters and to record their infrared spectra via messenger-tagged infrared multiple photon dissociation spectroscopy. With complementary quantum chemical calculations and molecular dynamics simulations, we determined that the most probable binding site of a metal, specifically a vanadium cation, on C60 is above a pentagonal center in an η5 fashion. We explored the bonding nature between C60 and V+ and revealed that the high thermal stability of this cluster originates from large orbital and electrostatic interactions. Through comparing the measured infrared spectra of [C60-Metal]+ with the observational Spitzer data of several fullerene-rich planetary nebulae, we proposed that the complexes formed by fullerene and cosmically abundant metals, for example, iron, are promising carriers of astronomical unidentified spectroscopic features. This opens the door for a real consideration of Kroto's 30-year-old hypothesis that complexes involving cosmically abundant elements and C60 exhibit strong charge-transfer bands, similar to those of certain unidentified astrophysical spectroscopic features. We compiled a VibFullerene database and extracted a set of vibrational frequencies and intensities for fullerene derivatives to facilitate their potential detection by the James Webb Space Telescope. In addition, we showed that upon infrared irradiation C60V+ can efficiently catalyze water splitting to generate H2. This finding is attributed to the novel geometric-electronic effects of C60, acting as "hydrogen shuttle" and "electron sponge", which illustrates the important role of carbon-based supports in single-atom catalysts. Our work not only unveils the basic structures and bonding nature of fullerene-metal clusters but also elucidates their potential importance in astrophysics, astrochemistry, and catalysis, showing the multifaceted character of this class of clusters. More exciting and interesting aspects of the fullerene-metal clusters, such as ultrafast charge-transfer dynamics between fullerene and metal and their relevance to designing hybrid fullerene-metal junctions for electronic devices, are awaiting exploration.

Pentagon, Hexagon, or Bridge? Identifying the Location of a Single Vanadium Cation on Buckminsterfullerene Surface

Buckminsterfullerene C60 has received extensive research interest since its discovery. In addition to its interesting intrinsic properties of exceptional stability and electron-accepting ability, the broad chemical tunability by decoration or substitution on the C60-fullerene surface makes it a fascinating molecule. However, to date, there is uncertainty about the binding location of such decorations on the C60 surface, even for a single adsorbed metal atom. In this work, we report the gas-phase synthesis of the C60V+ complex and its in situ characterization by mass spectrometry and infrared spectroscopy with the help of quantum chemical calculations and molecular dynamics simulations. We identify the most probable binding position of a vanadium cation on C60 above a pentagon center in an η5-fashion, demonstrate a high thermal stability for this complex, and explore the bonding nature between C60 and the vanadium cation, revealing that large orbital and electrostatic interactions lie at the origin of the stability of the η5-C60V+ complex.

AnAb-initiostudy of the Y decorated 2D holey graphyne for hydrogen storage application

Expanding pollution and rapid consumption of natural reservoirs (gas, oil, and coal) led humankind to explore alternative energy fuels like hydrogen fuel. Solid-state hydrogen storage is most desirable because of its usefulness in the onboard vehicle. In this work, we explored the yttrium decorated ultra porous, two-dimensional holey-graphyne for hydrogen storage. Using the first principles density functional theory simulations, we predict that yttrium doped holey graphyne can adsorb up to seven hydrogen molecules per yttrium atom resulting in a gravimetric hydrogen weight percentage of 9.34, higher than the target of 6.5 wt% set by the US Department of Energy. The average binding energy per H₂and desorption temperature come out to be -0.34 eV and ∼438 K, respectively. Yttrium atom is bonded strongly on HGY sheet due to charge transfer from Y 4d orbital to C 2p orbital whereas the adsorption of H₂molecule on Y is due to Kubas-type of interactions involving charge donation from H 1s orbital to Y 3d orbital and back donation with net charge gain by H 1s orbital. Furthermore, sufficient energy barriers for the metal atom diffusion have been found to prevent the clustering of transition metal (yttrium) on HGY sheet. The stability of the system at higher temperatures is analyzed usingAb-initiomolecular dynamics (AIMD) method, and the system is found to be stable at room and the highest desorption temperature. Stability of the system at higher temperatures, presence of adequate diffusion energy barrier to prevent metal-metal clustering, high gravimetric wt% of H₂uptake with suitable binding energy, and desorption temperature signifies that Y doped HGY is a promising material to fabricate high capacity hydrogen storage devices.

Alkali metal decorated C60 fullerenes as promising materials for delivery of the 5-fluorouracil anticancer drug: a DFT approach

The development of effective drug delivery vehicles is essential for the targeted administration and/or controlled release of drugs. Using first-principles calculations, the potential of alkali metal (AM = Li, Na, and K) decorated C60 fullerenes for delivery of 5-fluorouracil (5FU) is explored. The adsorption energies of the 5FU on a single AM atom decorated C60 are -19.33, -16.58, and -14.07 kcal mol-1 for AM = Li, Na, and K, respectively. The results, on the other hand, show that up to 12 Li and 6 Na or K atoms can be anchored on the exterior surface of the C60 fullerene simultaneously, each of which can interact with a 5FU molecule. Because of the moderate adsorption energies and charge-transfer values, the 5FU can be simply separated from the fullerene at ambient temperature. Furthermore, the results show that the 5FU may be easily protonated in the target cancerous tissues, which facilitates the release of the drug from the fullerene. The inclusion of solvent effects tends to decrease the 5FU adsorption energies in all 5FU-fullerene complexes. This is the first report on the high capability of AM decorated fullerenes for delivery of multiple 5FU molecules utilizing a C60 host molecule.

Ca functionalized N-doped porphyrin-like porous C60 as an efficient material for storage of molecular hydrogen

It is widely known that decorating metal atoms on defective carbon nanomaterials is a useful approach to enhance the hydrogen storage capacity of these systems. Herein, density functional theory calculations are used to determine the H₂ storage capacity of Ca functionalized nitrogen incorporated defective C₆₀ fullerenes (Ca₆C₂₄N₂₄). The strong binding, uniform distribution, and significant positive charges of the Ca atoms make this system effective material for storage of H₂. Ca₆C₂₄N₂₄ may adsorb a maximum of 6 hydrogen molecules per Ca atom, yielding a total gravimetric density of 7.7 wt %.

Possible effects of fluxionality of a cavitand on its catalytic activity through confinement

The discovery of fullerenes was a huge milestone in the scientific community, and with it came the urge to discover and analyze various small and large atomic and molecular clusters having a cavity. These cavitands of varied shapes and sizes have wide applications in the encapsulation of rare gas atoms to induce bond formation between them, storage of hydrogen and hydrocarbons to be used as alternative sources of fuel, catalyzation of otherwise slow reactions without using a catalyst, activation of small gas molecules, etc. Various cavitands like fullerenes, [ExBox]4+, cucurbit[n]urils, borospherenes, octa acid, etc. have been used for this purpose. Some clusters including cavitands exhibit fluxional behaviour. Systems in a confined environment often manifest interesting variations in their properties and behaviour, compared to their unconfined counterparts, facilitating the aforementioned applications. In this perspective article, we explore the possibility of making use of this extra degree of freedom, viz., the fluxionality, in changing the catalytic activity of the cavitand.

An Ultimate Investigation on the Adsorption of Amantadine on Pristine and Decorated Fullerenes C59X (X=Si, Ge, B, Al, Ga, N, P, and As): A DFT, NBO, and QTAIM Study

In this investigation, the feasibility of detecting the amantadine (AMD) molecule onto the outer surface of pristine fullerene (C[Formula: see text]), as well as C[Formula: see text]X ([Formula: see text], Ge, B, Al, Ga, N, P, and As) decorated structures, was carefully evaluated. For achieving this goal, a density functional theory level of study using the HSEH1PBE functional together with a 6-311G(d) basis set has been used. Subsequently, the B3LYP-D3, wB97XD and M062X functionals with a 6-311G(d) basis set were also employed to consider the single point energies. Natural bond orbital (NBO) and the quantum theory of atoms in molecules (QTAIM) were implemented using the B3LYP-D3/6-311G(d) method and the results were compatible with the electronic properties. In this regard, the total density of states (TDOSs), the Wiberg bond index (WBI), natural charge, natural electron configuration, donor–acceptor NBO interactions, and the second-order perturbation energies are performed to explore the nature of the intermolecular interactions. All of the energy calculations and population analyses denote that by adsorbing of the AMD molecule onto the surface of the considered nanostructures, the intermolecular interactions are of the type of strong physical adsorption. Among the doped fullerenes, Ge-doped structure has very high adsorption energy compared to other elements. Generally, it was revealed that the sensitivity of the adsorption will be increased when the AMD molecule interacts with the decorated fullerenes and decrease the HOMO–LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanocarrier.

Confinement Effects of a Noble Gas Dimer Inside a Fullerene Cage: Can It Be Used as an Acceptor in a DSSC?

A detailed density functional theory investigation of He₂-encapsulated fullerene C₃₆ and C₄₀ has been presented here. When confinement takes place, He-He bond length shortens and a non-covalent type of interaction exists between two He atoms. Energy decomposition analysis shows that though an attractive interaction exists in free He₂, when it is confined inside the fullerenes, repulsive interaction is observed due to the presence of dominant repulsive energy term. Fullerene C₄₀, with greater size, makes the incorporation of He₂ much easier than C₃₆ as confirmed from the study of boundary crossing barrier. In addition, we have studied the possibility of using He₂-incorporated fullerene as acceptor material in dye-sensitized solar cell (DSSC). Based on the highest energy gap, He₂@C₄₀ and bare C₄₀ fullerenes are chosen for this purpose. Dye constructed with He₂@C₄₀ as an acceptor has the highest light-harvesting efficiency and correspondingly will possess the maximum short circuit current as compared to pure C₄₀ acceptor.

Ag(I)-Hived Fullerene Microcube as an Enhanced Catalytic Substrate for the Reduction of 4-Nitrophenol and the Photodegradation of Orange G Dye

We report a facile approach to fabricate an Ag-embedded fullerene (C₆₀) catalyst by the chemical reduction of the AgNO₃ complex encapsulated fullerene microcrystal, which showed an enhanced catalytic reduction of 4-nitrophenol because of the strong absorption and propagation of H₂ along the fullerene surface. With the aid of visible-light radiation, photodegradation of orange G dye is achieved through the formation of an electron donor-acceptor dyad between plasmon Ag nanostructures and fullerene molecules, which effectively offsets the "electron-hole" recombination. Neither Ag nanoparticle nor fullerene crystal used in isolation could perform this chemical conversion, implying that the metal-fullerene hybrid structure is imperative for performing the catalytic reaction. The obtained Ag-embedded fullerene crystal is characterized by scanning electron microscopy (SEM), associated energy-dispersive X-ray spectroscopy (EDX) imaging, and X-ray photoelectron spectroscopy (XPS) and demonstrates that the present hybrid materials would add a supplemental member to a family of photocatalysts toward the organic synthesis and wastewater remediation.

The topology impact on hydrogen storage capacity of Sc-decorated ever-increasing porous graphene

Hydrogen storage capacity of different scandium (Sc)-decorated topological porous graphene (PG) was examined through density functional theory calculations. PGs were selected considering odd and even topological symmetries. Our calculations demonstrate that the most preferable sites for adsorption of Sc are located on the center of carbon rings on the perimeter of pores of all sizes. This results in stronger polarization and hybridization perpendicular to the surface leading to enhanced binding. Thus, all PGs are suitable for hydrogen storage under surrounded settings. Furthermore, results showed that the adsorption energies of H₂ molecules increased gradually with the size of pores. Analysis of charge density difference showed that the presence of Sc could play an efficient role for stronger adsorption of hydrogen molecules rather than increasing pore sizes. Furthermore, projected densities of states indicate that favorable systems for hydrogen storage are those that have higher overlap of individual states at Fermi level. Compared with H₂ adsorption on pure graphene, injecting topological defect such as hexagon porous and decoration with a transition metal atom such as Sc can effectively create much more conductive states at Fermi energy. Eventually, Sc decoration leads to n-type doping of PGs that help in much easier transportation of charge carriers and desirable storage of H₂ molecules.

Selected nanotechnologies and nanostructures for drug delivery, nanomedicine and cure

The development of nanoparticle-based drugs has provided many opportunities to diagnose, treat and cure challenging diseases. Through the manipulation of size, morphology, surface modification, surface characteristics, and materials used, a variety of nanostructures can be developed into smart systems, encasing therapeutic and imaging agents with stealth properties. These nanostructures can deliver drugs to specific tissues or sites and provide controlled release therapy. This targeted and sustained drug delivery decreases the drug-related toxicity and increases the patient's compliance with less frequent dosing. Nanotechnology employing nanostructures as a tool has provided advances in the diagnostic testing of diseases and cure. This technology has proven beneficial in the treatment of cancer, AIDS, and many other diseases. This review article highlights the recent advances in nanostructures and nanotechnology for drug delivery, nanomedicine and cures.

B12-containing volleyball-like molecule for hydrogen storage

A stable core-shell volleyball-like structure of B12@Li20Al12 has been proposed using first-principles calculations. This structure with T h symmetry is constructed with a core structure of I h-B12 and a volleyball-like shell of Li20Al12. Frequency analysis and molecular dynamics simulations demonstrate the exceptional stability of B12@Li20Al12. The chemical bonding analysis for B12@Li20Al12 is also conducted to confirm its stability and 46 multi-center two-electron σ bonds are observed, which are widely distributed throughout the core-shell structure. For the hydrogen storage capacity of the B12@Li20Al12, our calculated results indicate that about 58 H2 molecules can be absorbed at most, leading to a gravimetric density of 16.4 wt%. The exceptionally stable core-shell volleyball-like B12@Li20Al12 combined with its high hydrogen storage capacity indicates that it can be one of the outstanding hydrogen storage materials of the future.

Ab initio diabatic and adiabatic calculations for francium hydride FrH

Explicit ab initio diabatic and adiabatic calculations of potential energy curves (PECs) of the states ^1,3Σ⁺, ^1,3Π, and ^1,3Δ of francium hydride FrH have been carried out with several approaches.

Synergetic promotion by oxygen doping and Ca decoration on graphene for CO2 selective adsorption

The selective adsorption of CO2 by alkali earth metal (AEM)-decorated double vacancy graphene (DVG) was investigated with the first principles method. It is found that Be, Ca, Sr and Ba can be anchored stably on the DVG (whereas Mg cannot), and the Ca-decorated sample (Ca_DVG) possesses the strongest CO2 adsorption with a heat release of -0.45 eV per CO2. Furthermore, the doping of oxygen atoms on Ca_DVG (denoted as Ca_PyODVG) can remarkably increase the adsorption energy to -0.74 eV per CO2. This considerable promotion is ascribed to a synergetic effect of Ca decoration and O doping, which boosts extra electrons to transfer from the Ca_PyODVG substrate to the adsorbed CO2 molecule via the Ca 3p-O 2s hybridization. Notably, the obtained Ca_PyODVG is demonstrated to have a more practical CO2 desorption temperature, as well as a broader window for the selective adsorption of CO2 over CH4 and H2. Our theoretical results imply that Ca_PyODVG should be a promising candidate for CO2 capture. Additionally, the adsorption energy of CO2 is linearly correlated to the work function of a substrate, which may be used to accelerate the experimental screening of promising adsorbents.

Exfoliation, point defects and hydrogen storage properties of monolayer TiS3: an ab initio study

The possibility of H2 molecule adsorption on the basal plane of monolayer TiS3 at various sites has been studied. Among the studied adsorption sites, few sites were found to be suitable for physisorption with binding energy up to 0.10 eV per H2. To increase the activity of hydrogen sorption, the possibility of generating S-vacancies, by removing sulfur atoms from the basal plane of monolayer TiS3, was investigated. Despite the fact that the structures containing vacancies were found to be stable enough, there was no increase in the activity towards hydrogen adsorption. The same effect was obtained with the use of common methods of increasing of the H2 adsorption energy: the decoration of the two-dimensional material with alkali metals (Li, Na). This might be caused by the negatively charged surfaces of single layer TiS3, which hinder the increase in binding by alkali metals through a weak electrostatic interaction.

A potential material for hydrogen storage: a Li decorated graphitic-CN monolayer

Motivated by recent experimental developments of graphitic-CN (g-CN) sheets, we investigate the suitability of hydrogen storage on Li decorated g-CN via first-principles calculations.

Influence of nitrogen doping in sumanene framework toward hydrogen storage: A computational study

Two conditions are important to obtain appropriate substances for hydrogen storage; high surface area and fitting binding energy (BE). Doping is a key strategy that improves BE. We investigated hydrogen adsorption onto twenty six nitrogen disubstituted isomers of sumanene (C₁₉N₂H₁₂) by MP2/6-311++G(d,p)//B3LYP/6-31+G(d) and M06-2X/6-31+G(d) levels of theory. Effect of nitrogen doping in different positions of sumanene was checked. To obtain better BE, basis set superposition error (BSSE) and zero point energy (ZPE) corrections were used. Anticipating of adsorption sites and extra details about adsorption process was done by molecular electrostatic potential (MEP) surfaces. Various types of density of state (DOS) diagrams such as total DOS (TDOS), projected DOS (PDOS) and overlap population DOS (OPDOS) and natural bond orbital (NBO) analysis were used to find better insight on the adsorption properties. In addition of temperature depending of the BE, HOMO-LUMO gap (HLG), dipole moment, reactivity and stability, bowl depth and natural population analysis (NPA) of the isomers were studied. A physisorption mechanism for adsorption was proposed and a trivial change was seen. Place of nitrogen atoms in sumanene frame causes to binding energy increases or decreases compared with pristine sumanene. The best and the worst isomers and category of isomers were suggested.

Sc-Decorated Porous Graphene for High-Capacity Hydrogen Storage: First-Principles Calculations

The generalized gradient approximation (GGA) function based on density functional theory is adopted to investigate the optimized geometrical structure, electron structure and hydrogen storage performance of Sc modified porous graphene (PG). It is found that the carbon ring center is the most stable adsorbed position for a single Sc atom on PG, and the maximum number of adsorbed H₂ molecules is four with the average adsorption energy of −0.429 eV/H₂. By adding a second Sc atom on the other side of the system, the hydrogen storage capacity of the system can be improved effectively. Two Sc atoms located on opposite sides of the PG carbon ring center hole is the most suitable hydrogen storage structure, and the hydrogen storage capacity reach a maximum 9.09 wt % at the average adsorption energy of −0.296 eV/H₂. The adsorption of H₂ molecules in the PG system is mainly attributed to orbital hybridization among H, Sc, and C atoms, and Coulomb attraction between negatively charged H₂ molecules and positively charged Sc atoms.

Positively and Negatively Charged Cesium and (C60) m Cs n Cluster Ions

We report on the formation and ionization of cesium and C60Cs clusters in superfluid helium nanodroplets. Size distributions of positively and negatively charged (C60) m Cs n± ions have been measured for m ≤ 7, n ≤ 12. Reproducible intensity anomalies are observed in high-resolution mass spectra. For both charge states, (C60) m Cs3± and (C60) m Cs5± are particularly abundant, with little dependence on the value of m. Distributions of bare cesium cluster ions also indicate enhanced stability of Cs3± and Cs5±, in agreement with theoretical predictions. These findings contrast with earlier reports on highly Cs-doped cationic fullerene aggregates which showed enhanced stability of C60Cs6 building blocks attributed to charge transfer. The dependence of the (C60) m Cs3- anion yield on electron energy shows a resonance that, surprisingly, oscillates in strength as m increases from 1 to 6.

Chemical grafting of Co9S8 onto C60 for hydrogen spillover and storage

Metal modified C₆₀ is considered to be a potential hydrogen storage medium due to its high theoretical capacity. Research interest is growing in various hybrid inorganic compounds-C₆₀. While the design and synthesis of a novel hybrid inorganic compound-C₆₀ is difficult to attain, it has been theorized that the atomic hydrogen could transfer from the inorganic compound to the adjacent C₆₀ surfaces via spillover and surface diffusion. Here, as a proof of concept experiment, we graft Co₉S₈ onto C₆₀via a facile high energy ball milling process. The Raman, XPS, XRD, TEM, HTEM and EELS measurements have been conducted to evaluate the composition and structure of the pizza-like hybrid material. In addition, the electrochemical measurements and calculated results demonstrate that the chemical "bridges" (C-S bonds) between these two materials enhance the binding strength and, hence, facilitate the hydriding reaction of C₆₀ during the hydrogen storage process. As a result, an increased hydrogen storage capacity of 4.03 wt% is achieved, along with a favorable cycling stability of ∼80% after 50 cycles. Excluding the direct hydrogen storage contribution from Co₉S₈ in the hybrid paper, the hydrogen storage ability of C₆₀ was enhanced by 5.9× through the hydriding reaction caused by the Co₉S₈ modifier. Based on these experimental measurements and theoretical calculations, the unique chemical structure reported here could potentially inspire other C₆₀-based advanced hybrids.

Evidence of interface exchange magnetism in self-assembled cobalt-fullerene nanocomposites exposed to air

We report on the establishing of an exclusive magnetic effect in air-exposed Co_xC₆₀ nanocomposites (x > 2) created through self-assembling in the depositing mixture. In order to verify the influence of ambient air on the Co_xC₆₀ mixture film, we have studied in detail the film magnetization at rather low temperatures, which provides their ferromagnetic behavior. Tracing the possible exchange bias effect, we distinguished a clear vertical shift of the hysteresis loops recorded for the air-exposed Co_xC₆₀ films in the field cooling (FC) regime. The detected vertical shift of the FC loops is caused by an uncompensated magnetic moment M _u induced by exchange coupling of the Co spins at the Co/CoO interface. This interface arises due to the oxidation of small Co clusters distributed in a C₆₀-based matrix of self-assembled composite films, which occurs during air exposure. The core-shell structure of the Co/CoO magnetic clusters (about 2-3 nm in size) consisting of a ε-Co core and fcc-CoO shell was confirmed by means of transmission electron microscopy. Established interface magnetism testifies to a composite nanostructure in the Co_xC₆₀ mixture film with x > 2 and explains the influence of air exposure on the film structure. The discovered magnetic effect implies a new application potential for cobalt-fullerene composites in sensors and catalysis.

Optimal hydrogen storage in sodium substituted lithium fullerides

A relevant improvement in the hydrogen storage capability of lithium fullerides is obtained by the co-intercalation of a small amount of sodium.

Manipulating energy storage characteristics of ultrathin boron carbide monolayer under varied scandium doping

We report, for the first time we believe, a detailed investigation on hydrogen storage efficiency of scandium (Sc) decorated boron carbide (BC₃) sheets using spin-polarized density functional theory (DFT).

Lithium-Decorated Borospherene B40: A Promising Hydrogen Storage Medium

The recent discovery of borospherene B₄₀ marks the onset of a new kind of boron-based nanostructures akin to the C₆₀ buckyball, offering opportunities to explore materials applications of nanoboron. Here we report on the feasibility of Li-decorated B₄₀ for hydrogen storage using the DFT calculations. The B₄₀ cluster has an overall shape of cube-like cage with six hexagonal and heptagonal holes and eight close-packing B₆ triangles. Our computational data show that Li_m&B₄₀(1-3) complexes bound up to three H₂ molecules per Li site with an adsorption energy (AE) of 0.11-0.25 eV/H₂, ideal for reversible hydrogen storage and release. The bonding features charge transfer from Li to B₄₀. The first 18 H₂ in Li₆&B₄₀(3) possess an AE of 0.11-0.18 eV, corresponding to a gravimetric density of 7.1 wt%. The eight triangular B₆ corners are shown as well to be good sites for Li-decoration and H₂ adsorption. In a desirable case of Li₁₄&B₄₀-42 H₂(8), a total of 42 H₂ molecules are adsorbed with an AE of 0.32 eV/H₂ for the first 14 H₂ and 0.12 eV/H₂ for the third 14 H₂. A maximum gravimetric density of 13.8 wt% is achieved in 8. The Li-B₄₀-nH₂ system differs markedly from the previous Li-C₆₀-nH₂ and Ti-B₄₀-nH₂ complexes.

Metalized B40fullerene as a novel material for storage and optical detection of hydrogen: a first-principles study

Based on (van der Waals corrected) density functional theory, we show that alkali metal (AM) adsorbed on B₄₀can serve as a promising candidate not only for hydrogen storage, but also for hydrogen detection.

DFT study of Rh-decorated pristine, B-doped and vacancy defected graphene for hydrogen adsorption

Rh adatom stability on graphene, with and without defects has been investigated by density functional theory (DFT). The feasibility to achieve uniform dispersion for the metallic atom and the hydrogen storage capacity for each system were evaluated.

Theoretical study of the interaction between molecular hydrogen and [MC60]+ complexes

In this work we present a density functional theory study of the interaction between a positively charged exohedral metallofullerene and several hydrogen molecules.