Grand canonical Monte Carlo study on the hydrogen adsorption behaviour of four graphite intercalation compound clusters

Discrete–variational Xα calculations of graphite and alkali–metal graphite intercalation compounds

Understanding radioactive dust behavior is essential for nuclear safety assessments, particularly in high‐temperature pebble‐bed reactors. Current knowledge gaps in microscopic interaction mechanisms under extreme conditions have hindered progress in this field. Our study bridges this gap through systematic modeling of cesium‐graphite systems, focusing on the adsorption behavior of cesium's predominant chemical forms (Cs2, Cs4, Cs₂CO₃, and CsOH) on graphite clusters, guided by thermodynamic predictions for reactor conditions. The results demonstrate that atomic cesium exhibits superior adsorption affinity due to dominant electrostatic interactions, while molecular forms (Cs₂CO₃/CsOH) show reduced adsorption capacity as their oxygen atoms create an energetic barrier that counteracts the combined effects of dispersion and electrostatic forces. Temperature‐dependent analysis reveals atomic cesium remains stably adsorbed on graphite surfaces below 627 K. These findings provide both a predictive framework for fission product morphology in radioactive dust and fundamental insights into interfacial interactions that govern cesium adsorption behavior—critical knowledge for enhancing nuclear reactor safety protocols.

A thermodesorption study of first stage graphite FeCl3 intercalation compounds

While most studies on graphite intercalation compounds (GICs) as hydrogen storage materials use molecular dynamics and first principles approaches, few focus on the detailed hydrogen adsorption characteristics of the intercalators themselves. Usually, intercalators are divided into metals, halogens, and compounds. However, the hydrogen adsorption mechanisms of the common intercalators such as alkali metals Li and Na, halogen elements F, and compounds FeCl3 have not yet been revealed. Therefore, we studied the microscopic interactions between Li, Na, F, FeCl3 intercalators, and H2, including charges, potentials, intermolecular forces, and molecular orbital mixing, using density functional theory (DFT). Our study results show that compared to current hydrogen storage materials like planar graphite, GICs have better hydrogen storage capacity due to their interlayer hydrogen adsorption properties. Each Li, Na, and F atom can adsorb 6 H2, while 8 H2 was adsorbed by the FeCl3 molecule. Using Li and Na atoms as intercalators, GICs adsorb hydrogen through van der Waals forces with adsorption energy values of 0.15eV and 0.16eV, respectively, exhibiting a physical adsorption form. Using F atoms as intercalators, the adsorption energy is similar to alkali metals, and the adsorption form is also similar. However, F atoms gain charge from H2 when adsorbing, which is opposite to the alkali metals losing charge characteristic. Using FeCl3 as an intercalator, GICs have reached a maximum interlayer spacing distance of 9.40Å, with an adsorption energy value of 1.06eV, exhibiting a slight polarisation phenomenon. The adsorption form is a type of physical-chemical adsorption similar to metal dihydrogen complexes caused by Kubas coordination. By comparison, we found that FeCl3 intercalators have the highest hydrogen adsorption energy and demonstrate considerable stability, making them the most promising intercalators for hydrogen adsorption among the four. In addition, compared to the strong chemical adsorption of H2 by transition metals loaded at the boundary of carbon nanomaterials, FeCl3 in the interlayer space evenly adsorbs each H2 through physical-chemical adsorption, which helps to dissociate and release H2. The GIC structure in this study was constructed and optimised using the Dmol3 module based on the GGA-PBE method from the Materials Studio 2020 software package. The hydrogen adsorption system was calculated using the Gaussian 09W software package based on the B3LYP functional with 6-31G * basis set, and metal elements were calculated using the SDD basis set. The charge transfer, electrostatic potential, and independent gradient model based on Hirshfeld partition and density of states are processed using the Multiwfn 3.8 package. All images are rendered using the VMD 1.91 package.

Hydrogen adsorption and diffusion behavior in kaolinite slit for underground hydrogen storage: A hybrid GCMC-MD simulation study

Due to the increasing demand of Al[Formula: see text]N[Formula: see text] in optoelectronics and sensing materials, we intended to investigate the adsorption behavior, electronic nature and NLO response of hydrogen and different metals decorated Al[Formula: see text]N[Formula: see text] nanocages. Different systems are designed by hydrogen adsorption and encapsulation of metals (Li, Na and K) in Al[Formula: see text]N[Formula: see text]. Density functional theory at B3LYP functional with conjunction of 6-31G([Formula: see text], [Formula: see text] basis set is utilized in order to gain optimized geometries. Different calculations including linear and first-order hyperpolarizability are conducted at same level of theory. Instead of chemiosorption, a phyisosorption phenomenon is seen in all hydrogen adsorbed metal encapsulated Al[Formula: see text]N[Formula: see text] nanoclusters. The [Formula: see text] analysis confirmed the charge separation in hydrogen adsorbed metal encapsulated nanocages. Molecular electrostatic potential (MEP) analysis cleared the different charge sites in all the systems. Similarly, frontier molecular orbitals analysis corroborated the charge densities shifting upon hydrogen adsorption on metal encapsulated AlN nanocages. HOMO–LUMO band gaps suggest effective use of H2-M-AlN in sensing materials. Global indices of reactivity also endorsed that all hydrogen adsorbed metal encapsulated systems are better materials than pure Al[Formula: see text]N[Formula: see text] nanocage for sensing applications. Lastly, linear and first hyperpolarizability of H2-M-AlN nanocages are found to be greater than M-AlN and pure AlN nanocages. Results of these parameters recommend metal encapsulated nanocages as efficient contributors for the applications in hydrogen sensing and optoelectronic devices.

Synthesis and properties of ternary GIC with iron or copper chlorides

Hydrogen adsorption and storage behaviors of Li-decorated PdS2 monolayer: An extended tight-binding study based on DFT

Extensive investigatiofis have been carried out on various graphite intercalation compounds (GICs), but the nature of the microscopic mechanisms have not been fully understood. The transport properties of these compounds show drastic changes from the parent graphite [1] and require more theoretical investigations. As an extension of our studies on graphite ferric chloride intercalation compounds (GFeC13) of both pure and mixed stages, we report our measurements of the Hall coefficient at low magnetic fields. The graphite ferric chloride intercalation compounds of pure and mixed stages were prepared by the conventional two-zone vapour transport technique with the graphite zone at higher temperature than the intercalant zone. The temperature conditions used for the synthesis are given in Table I. This particular system was found to be environmentally stable. The samples were characterized initially by the increase in weight percentage over that of initial graphite. X-ray characterization was carried out using CoK« radiation of wavelength 0.17902 nm. The stages were identified from the (0 0 1) reflections of the X-ray diffractogram. According to the classical model of staging [2], the c axis repeat distance Ic is related to the stage number n by the simple relation:

Preface. Acknowledgements. Part 1: Lectures. Intercalation compounds for energy storage C. Julien, et al. Lithium intercalation compounds - The reliability of the rigid-band model C. Julien. Overview of carbon anodes for lithium-ion batteries K. Zaghib, K. Kinoshita. Electronic structure of various forms of solid state carbons - Graphite intercalation compounds J. Conard. From intercalation compounds to inserted clusters e.g. Li in carbon superanodes for secondary batteries J. Conard. Lithium NMR in lithium-carbon solid state compounds J. Conard, P. Lauginie. Critical review of H/Carbon literature and ab-initio research for a chemical site between two coronenes F. Marinelli, et al. Carbon-based negative electrodes of lithium-ion batteries obtained from residua of the petroleum industry R. Alcantara, et al. Hydrogen in metals J. Huot. Effects of composition in La/Ni-based intermetallic compounds used as negative electrodes in Ni-MH batteries R. Baddour-Hadjean, et al. Lithium insertion compounds for energy storage A. Manthiram. Chemical and structural stabilities of layered oxide cathodes A. Manthiram. In situ preparation of composite electrodes: antimony alloys and compounds R. Alcantara, et al. On the use of in-situ generated tin-based composite materials in lithium-ion cells R. Alcantara, et al. Physical chemistry of lithium intercalation compounds C. Julien. Lattice dynamics of manganese oxides and their intercalated compounds C. Julien, M. Massot. Physical chemistry and electrochemistry of intercalation in disordered compounds C. Julien, B. Yebka. Modifief host lattices for Li intercalation with improved electrochemical properties J.P. Pereira-Ramos, et al. Surface science investigations of intercalation reactions with layered metaldichalcogenides W. Jaegermann, D. Tonti. Conductive polymers and hybrid materials as insertion electrodes for energy storage applications P. Gomez-Romero. An electrochemical point of view on the intercalation compounds A. Momchilov. Manganese dioxides promising cathode materials for lithium batteries B. Banov. Part 2: Seminars. Impedance of diffusion of inserted ions. Simple and advanced models J. Bisquert. Dielectric relaxation spectroscopy for probing ion/network interactions in solids F. Henn, et al. Cations mobility and water adsorption in zeolites G. Maurin, et al. Strategies to improve the cycling performance of lithium storage alloys M. Wachtler, et al. Nanoscaled containers for hydrogen I.D. Dragieva, et al. Nanocrystalline materials for lithium batteries C.W. Kwon, et al. Study of fluorinated graphite intercalation compounds I.P. Asanov, et al. Insertion of rare-earth metals into AgI-based compounds - First evidence of disordering and strong modification of ss- and a-AgI crystal structures A.L. Despotuli. Structural characterization of Mg treated LiCoO2 intercalation compounds R. Stoyanova, et al. Electronic structure of oxygen in delitiated LiTMO2 studied by electron energy-loss spectrometry J. Graetz, et al. Short-range Co/Mn ordering and electrochemical intercalation of Li into Li[Mn2-yCoy]O4 spinels, 0

Adsorption equilibrium of hydrogen adsorption on activated carbon, multi-walled carbon nanotubes and graphene sheets

Study of Hydrogen Adsorption on Pt and Pt-Based Bimetallic Surfaces by Density Functional Theory

Theoretical insight into the hydrogen adsorption on MoS2 (MoSe2) monolayer as a function of biaxial strain/external electric field

Graphite intercalation compounds (GICs) are commonly used as anode materials for alkali metal-ion batteries, such as Li-ion and K-ion batteries. Although typically prepared as a low-stage intercalation compound (with a high concentration of the intercalating metal), over several electrochemical cycles, the distribution of intercalate within the graphite sample is expected to be non-uniform with domains of high-stage regions where the intercalant fraction is low [1]. The mechanism of interlayer electron transport in GICs strongly depends on the intercalation staging and temperature, and is expected to vary over the lifetime of a battery.High-stage GICs and highly oriented pyrolytic graphite (HOPG), which is the upper limit of infinite-stage GIC, have an out-of-plane electrical conductivity that exponentially increases with temperature, whereas low-stage GICs have a conductivity that decreases as a function of temperature [2, 3, 4]. Although out-of-plane electron transport in low-stage GICs can be described by a metallic conduction model, the mechanism of out-of-plane electron transport in HOPG and high-stage GICs is a hitherto unresolved problem [5]. Out-of-plane electrical conductivity for HOPG and high-stage GICs increases exponentially with temperature, which cannot be described by metallic conduction, nor by conventional impurity or defect hopping mechanisms [6].We propose a new mechanism of electron transport that takes place in HOPG and high-stage GICs at temperatures relevant to battery operation. Electrons are transferred between graphite and intercalant layers through tunneling that is enhanced by large amplitude out-of-plane phonon modes in graphite layers. Due to weak interlayer interactions in adjacent graphite layers, GICs can accommodate large amplitude phonon modes in the out-of-plane direction that locally enhance the interlayer electron tunneling probability. The tunneling enhancement is temperature dependent, and exponentially depends on the population of out-of-plane phonon modes excited at a given temperature. The expression for the conductivity 𝜎 for the phonon amplitude-driven tunneling mechanism as a function of temperature T is shown in Eq. 1; the exponential dependence of conductivity with temperature qualitatively agrees with experimental observations in HOPG and high-stage GICs. On a quantitative level, we also observe from Fig.1 that the theory agrees with experimental values for out-of-plane conductivity in HOPG.The phonon amplitude-driven tunneling mechanism of electron transport is relevant in describing the kinetic over-potential in batteries that employ layered materials as anodes in ambient temperature operating conditions, and optimally sizing the anode accounting for both electron transport and ion diffusion rates.

Behavior of hydrazine and its effects on the adsorption of hydrogen at Pt(322) and Pt(111) electrodes in sulfuric acid solutions