Hydrogen Adsorption Properties Research Articles

Li-decorated C48B12 and Li12C48B12-impregnated MOF-5 for hydrogen storage: A multi-scale simulation study

In this study, we employed density functional theory (DFT) to investigate the adsorption sites and quantities of Li atoms on the C48B12 surface. Additionally, we examined the hydrogen adsorption properties of the formed Li12C48B12 through ab initio molecular dynamics (AIMD) simulations. Our AIMD simulations confirmed the stability of adsorbed Li atoms on the C48B12 surface, computed adsorbed H2 quantities, and predicted gravimetric densities of H2 adsorption on Li12C48B12 at 77 K and 298 K. Grand Canonical Monte Carlo simulations explored the H2 gravimetric densities of pure MOF-5, C48B12-impregnated MOF-5, and Li12C48B12-impregnated MOF-5 at 77 K and 298 K within 100 bar. Li doping on the C48B12 surface did not significantly enhance the gravimetric densities of H2 in MOF-5 but enhanced the stability of H2 adsorption in MOF-5.

Synergistic Effects of Carbon Vacancies in Conjunction with Phosphorus Dopant across Bilayer Graphene for the Enhanced Hydrogen Evolution Reaction.

Bilayer graphene (BLG) exhibits distinct physical properties under external influences, such as torsion and structural defects, setting it apart from monolayer graphene. In this study, we explore the synergistic effects of carbon vacancies, in conjunction with phosphorus dopants, across BLG, focusing on their impact on structural, magnetic, electrical, and hydrogen adsorption properties. Our findings reveal that the substitutional doping of a phosphorus atom into a single carbon vacancy in a graphene layer induces substantial structural distortion in BLG. In contrast, doping phosphorus into a double vacancy maintains the flat structure of graphene layers. These distinct layer structures affect the electron distribution and spin arrangement, leading to varied electronic configurations and intriguing magnetic behaviors. Furthermore, the presence of abundant unsaturated electrons around the vacancy promotes the capture and bonding of hydrogen atoms. Hydrogen adsorption on BLG results in substantial orbital hybridization, accompanied by significant charge transfer. The calculated Gibbs free energies for hydrogen adsorption on BLG range from -0.08 to 0.09 eV, indicating exceptional catalytic activity for the hydrogen evolution reaction. These findings carry implications for optimizing the properties of graphene layers, making them highly desirable for applications such as catalysis.

First‐principle screening of corrosion resistant solutes (Al, Zn, Y, Ce, and Mn) in Mg alloys for Integrated Computational Materials Engineering guided stainless Mg design

AbstractMg alloy suffers from its poor corrosion resistance as a result of anodic dissolution of Mg and hydrogen evolution reaction (HER) in humid environments. In this study, the effects of alloying elements (Al, Zn, Y, Ce, and Mn) on both processes in Mg alloys have been quantitatively predicted. Using first‐principle calculations, we first obtained the substitution energies of alloying elements to compare their segregation preference, and then analyzed the influence of solutes at different layers on the stability and hydrogen adsorption properties of Mg(0001) surface by calculating the formation enthalpy, surface energy, vacancy formation energy, work function, Bader charge, deformation charge density, and adsorption free energy of H atom. It has been found that, on the one hand, the interior Mn solute atoms reduce the dissolution of Mg atoms and the transfer of electrons, consequently slowing down the anodic dissolution process. On another hand, the Mn, Y, and Ce elements on the surface inhibit the cathodic HER process by elevating the absolute value of hydrogen adsorption free energy, as a result of those solutes effectively controlling H adsorption behavior on Mg(0001) surface. In contrast, all five elements dissolved inside the Mg grain do not show significant effects on the H adsorption behavior.

Electronic and structural properties of hydrogen adsorption on γ-Graphyne and γ-BNyne

While the study of one-dimensional materials such as carbon nanotubes and boron-nitrogen structures have attracted technological interest, the appearance of new two-dimensional materials has expanded the spectrum with new potential applications. The most recent report published in 2022 on the synthesis of γ-graphyne has sparked scientific interest in describing the properties that this material and its analogs may exhibit under different physical and chemical conditions. In this study, the effect of hydrogen molecule adsorption on γ-BNyne surface is presented for the first time and compared with the properties reported for γ-graphyne, these calculations have been carried out through first-principles calculations using Density Functional Theory with DFT-D3 Grimme’s correction. The results showed that molecular hydrogen adsorption on these two-dimensional surfaces does not significantly alter their pristine structural and electronic properties, demonstrating their stability under molecular hydrogen adsorption conditions. The results presented here contribute to the promotion of these two-dimensional materials as potential candidates for technological applications such as nanosensors, nanomedicine, and hydrogen storage, among others.

DFT study of B substitution on the hydrogen storage properties of pt-modified conical cup-stacked carbon nanotube

The conical cup-stacked carbon nanotubes (CSCNTs) are stacked by individual conical graphene layers (CGL) with a large number of active C atoms on their walls, making them an effective hydrogen storage material. In this paper, the structural properties of the loaded Pt atom and its hydrogen storage properties were investigated using density functional theory (DFT) with and without substitution of B atoms on the edges of the CGL. It was found that the loaded Pt atoms could adsorb 3 H2 and up to 7 H2 without replacing the C atoms with B atoms as well as replacing the C atoms at the edges of the CGL with B atoms at different positions, respectively. Therefore, we conclude that the position of the substituted B atom at the edge of the CGL has an important effect on the position of the loaded Pt atom and its hydrogen adsorption and storage properties.

ВЛИЯНИЕ ФАЗОВОГО СОСТАВА МАТЕРИАЛОВ СИСТЕМЫ ТИТАН-ЖЕЛЕЗО НА ВОДОРОДНУЮ ЕМКОСТЬ

The hydrogen adsorption properties of the phases in the materials of the Ti-Fe system have been considered. It has been shown that an increase in the content of β-Ti and Ti2Fe in their structure is accompanied by a significant increase in hydrogen absorption during primary hydrogenation. The methods of mathematical data processing based on the classical Avraham-Yerofeev equation allowed us to reveal that hydrogen saturation of the materials under consideration starts from formation of hydrogen solid solutions in the initial material phases and continues with formation of the hydride phases after the latent period.

Synthesis of Graphdiynes, Morphological Study, and Comparative Analysis of the Hydrogen Adsorption Properties of Graphenes and Graphdiynes

Synthesis of Graphdiynes, Morphological Study, and Comparative Analysis of the Hydrogen Adsorption Properties of Graphenes and Graphdiynes

Hydrogen evolution reaction catalyzed by MoS2/CoS2 supported on nanocarbon hybrid in acidic medium

There is a high demand for evolving cost-operative and efficient non-noble electrocatalysts for hydrogen evolution reaction (HER). Free-standing MoS2 and their heterostructures are emerging as potential electrocatalysts due to their electrochemical stability in harsh acidic mediums. Herein, we report a one-pot hydrothermal synthesis of MoS2/CoS2 heterostructure with and without the support of carbon nanostructures. The electrical conductivity of the support material is enhanced by introducing f-MWCNT, which acts as pillars between the rGO layers, thus exposing a larger quantity of active sites that favors the hydrogen adsorption property and reduces the charge transfer resistance for facilitating the HER kinetics. The interfacial interaction between MoS2 and CoS2 with the synergistic effect of rGO/f-MWCNT (nanocarbon hybrid, NCHy) results in a potential catalyst yielding a current density of −10 mA/cm2 at −133 mV with an exchange current density value of 0.34 mA/cm2 and turnover frequency of 1.33/s. Catalyst stability is examined using a chronoamperometry test (CA) for 14 h, and the material shows high stability. Also, a study of change in electrochemical activity with change in transition metal in the heterostructure is systematically performed.

Tuning the ultra-microporosity in hierarchical porous carbons derived from amorphous cellulose towards a sustainable solution for hydrogen storage

Activated carbons exhibit a high grade of porosity, which together with structural stability, regenerability and cyclability makes them capable of achieving excellent hydrogen adsorption capacity. A further advantage comes from the ease of production and the use of recyclable and biocompatible materials. A simple way to produce activated carbons from amorphous cellulose involves procedures in which a pyrolysis process is combined with physical activation in CO2.We used this approach by optimizing the production process tuning the activation times. The aim is to evaluate the influence of this process parameter on the formation of the specific surface area, the pore volume and fraction of micropores with a typical size <2 nm. The influence of these structural parameters on the hydrogen adsorption properties was then evaluated. The textural and adsorption characteristics were investigated using a commercial volumetric apparatus (ASAP 2460, Micromeritics) at −196 °C and pressures between 0 and 1 bar, while the morphological properties were investigated using scanning electron microscopy.The results show that the nanostructured samples are characterized by a very high degree of ultra-microporosity (<0.7 nm) with an average pore size between 0.5 and 0.6 nm and a high specific surface area, reaching maximum values around 1500 m2/g and micropore volume up to 0.58 cc/g. These morphological characteristics strongly influence the hydrogen adsorption properties, where the molecules adsorbed reach values very close to the coverage of ideal monolayer. The synthesized activated carbon samples show a higher hydrogen adsorption capacity than similar commercial materials tested under the same thermodynamic conditions.

On the hydrogen storage performance of metal-decorated beryllium polynitrides: Ab-initio investigations

Recently, two-dimensional materials (2D) have received a lot of attention as potential H2-storage applications. In this way, the recent successful synthesis of beryllium polynitride monolayer has raised our interest regarding the capacity of this promising 2D material to store hydrogen. For this purpose, first principle calculations with DFT-D3 dispersion corrections are used in this work to particularly investigate its hydrogen storage properties. Our results demonstrate that the adsorption energy of a H2 molecule on pristine BeN4 does not exist in the desirable energy range. For this reason, two strategies which are the decoration of lithium metal-atoms and the substitution of beryllium atom by one boron atom are simultaneously performed. The obtained results unveil a marked enhancement of hydrogen adsorption properties where the 2Li-decorated 1B–BeN4 could have 13H2 molecules stored, between values of adsorption energy going from −150 to −600 meV/H2, and a theoretical gravimetric density up to 6.06 wt%, exceeding the US Department of Energy's (DOE) required standards. Using the Van't Hoff equation as a base, the desorption temperature was higher than the critical point of hydrogen.

Carbon doping of B6N6 monolayer can improve its hydrogen storage performance effectively: A theoretical study

In this paper, a new two-dimensional B6N6 monolayer is investigated as a type of promising material for hydrogen storage. The average binding energy between Lithium and BN monolayer will be significantly increased from 0.80 eV to 2.42 eV and the metal agglomeration is also effectively avoided by the substitution of one nitrogen atom with one carbon atom. We use Density functional computations to check the hydrogen adsorption properties and find up to ten hydrogen molecules will be adsorbed on the double side Lithium decorated BNC monolayer with the adsorption energy of per H2 from 0.19 eV to 0.27 eV. The maximum storage gravimetric capacity of hydrogen can reach to 11.1 wt%. Meanwhile, the molecular dynamics (MD) calculations confirm that the 10H2@Li-decorated BNC structure is still thermodynamic stable. In addition, the simulation results of Grand Canonical Monte Carlo (GCMC) further prove that the hydrogen gravimetric density (HGD) is expected to reach to 7.48 wt% at room temperature (298 K).

АНАЛИЗ ВЛИЯНИЯ ФАЗОВОГО СОСТАВА МАТЕРИАЛОВ СИСТЕМЫ "ТИТАН-ЖЕЛЕЗО" НА ВОДОРОДНУЮ ЕМКОСТЬ ПРИ ПЕРВИЧНОМ ГИДРИРОВАНИИ

The hydrogen adsorption properties of the phases in the materials of the Ti-Fe system have been considered. It has been shown that an increase in the content of β-Ti and Ti2Fe in their structure is accompanied by a significant increase in hydrogen absorption during primary hydrogenation. The methods of mathematical data processing based on the classical Avraham-Yerofeev equation allowed us to reveal that hydrogen saturation of the materials under consideration starts from formation of hydrogen solid solutions in the initial material phases and continues with formation of the hydride phases after the latent period.

Alkali cations and H2 molecules on BN-doped carbon nanoflakes: Theoretical study

Non-covalent interactions of two cations (Li+ and Na+) and hydrogen molecules with coronene and hexagonal boron nitride models as well as their heterostructures (mBNC and pBNC) were studied by using a set of theoretical methods. It was shown that the shapes of boron nitride moieties in the graphene-like framework have a strong influence on the cation-π interactions. Decomposition of the interaction energy (Eint) was classified as consisting mainly of the inductive energy term (Eind), which is followed by the electrostatic term (Eel). Hydrogen adsorption, however, depends strongly on both these terms, and in the case of numerous adsorbed H2 molecules, the dispersion interactions (Edisp) are also of importance. The assessed hydrogen capacity of studied structures reaches 5.5 wt%. The present investigation explicitly shows that cation-π and, in some cases, hydrogen adsorption properties can be easily modified by a B and N atoms introduction in the carbon nanoflakes, and, hence, it establishes the route to the remarkable adsorbent materials.

Improved thermal management in HKUST-1 composites upon graphite flakes incorporation: Hydrogen adsorption properties

HKUST-1-based composites have been synthesized through the incorporation of synthetic graphite flakes in the MOF synthesis media. The presence of flakes gives rise to high quality HKUST-1 crystals, combining different morphologies (octahedral-shape crystals, cauliflower-shape crystals and truncated pyramids). The incorporation of graphite in the composites improves the structural stability of the embedded nanocrystals upon a conforming step at 377 kg/cm2 (0.5 tons), with limited structural damage (below 10% BET surface area reduction as compared to the 40% observed for pure HKUST-1). Furthermore, composites exhibit a significant improvement in thermal management, associated with the excellent thermal and electrical properties of the graphite microdomains incorporated. The improved stability of the composites is also reflected in the adsorption performance for hydrogen at atmospheric pressure and cryogenic temperatures, with a significant preservation of the adsorption properties (gravimetric capacity, <15% decrease vs powders) in the monoliths containing graphite. The best adsorption performance is achieved with sample HKUST-1@10GF, in monolithic form, with a volumetric excess uptake at 0.1 MPa and −195 °C close to 18.7 g/L. This value is among the best described in the literature for monolithic MOFs under similar adsorption conditions.

Influencing mechanism of carbon monoxide on the hydrogen absorption performance of Zr2Fe

Zr2Fe is considered as the promising hydrogen isotopes trapping material to control the quantity of tritium generated in deuterium–tritium fusion reaction. However, the vulnerability to poisoning by impurity gases such as carbon monoxide is the bottleneck for their applications. In this study, we show from our DFT calculations that the Zr2Fe(101) surface is saturated with 13CO molecules and the hollow site is the most stable CO adsorption site. The adsorption energy of CO is much lower than that of hydrogen, resulting in the preferential adsorption of CO on Zr2Fe(101). The dependence of the Gibbs free energies of CO on the temperatures under UHV conditions were also obtained. The climbing-image nudged elastic band results reveal that CO pre-coverage would block the hydrogen adsorption sites and affect the hydrogen diffusion. The Sieverts analysis demonstrates that even the low concentration CO is a fatal poison to the hydrogenation process of Zr2Fe at ambient temperature. Hydrogen absorption may occur at a higher temperature with a lower absorption rate and capacity, as CO starts to desorpt from Zr2Fe(101) with the increase of temperature and thus making H2 absorption possible, even though the H diffusion energy barriers are relatively high. Our results provide the basis for exploring the influence mechanisms of the impurity gas CO on the hydrogen adsorption properties of the Zr-based alloys, which would be beneficial for the applications of metal getter of tritium-containing waste gas.

DFT study of hydrogen interaction with transition metal doped graphene for efficient hydrogen storage: effect of d-orbital occupancy and Kubas interaction.

Hydrogen adsorption on pristine graphene (PG), graphene with defect (GD), and transition metal (TM) (Ag, Au, Cu, and Fe) doped graphene is systematically investigated for potential hydrogen storage using density functional theory. The stability of the TM atom doped graphene has been analysed by studying the binding energy and the electron density distribution. The TM atom-doped GD shows better binding energy and electron density overlap than PG; therefore, the TM/GD system has been considered and analysed for hydrogen adsorption. The hydrogen adsorption property is studied by examining the adsorption energy, mode of H2, density of states (DOS), charge density difference, and Löwdin charges before and after adsorption to find a better TM/GD system for hydrogen storage. The Fe/GD system shows higher hydrogen adsorption energy and hydrogen in its stable Kubas mode. Furthermore, two to five H2 molecule adsorption and desorption is studied. The increase in the number of H2, which changes the DOS at the Fermi level, suggests that one can predict H2 concentration by measuring conductivity changes. The present work is focused on studying the interaction between H2 and TM/GD systems, which will help understand the basic adsorption mechanism for practical hydrogen storage.

Metal doped tetrahedral silsesquioxane cages for hydrogen storage

The hydrogen adsorption properties of Tetrahedral Silsesquioxane Si4O6H4 (TS) cages doped with Be, Li, Sc and Ti atoms are studied in different spin state using density functional theory with M062X functional. Initially-one of the four hydrogen atoms in TS cage was substituted by metal atoms. Doublet and singlet are the lowest energy state for TS-Be and TS-Li respectively with respective H2 uptake capacity of 1.79 and 3.56 wt%. Triplet and quartet are the lowest energy state for TS-Sc and TS-Ti respectively. TS-Sc (singlet) and TS-Ti (doublet) cage interacts with seven and six hydrogen molecules respectively with respective gravimetric H2 capacity of 5.25 and 4.51 wt%. TS-Sc in triplet state could adsorb six H2 molecules whereas TS-Ti in quartet state could adsorb five H2 molecules with respective H2 uptake capacity of 4.5 wt% and 3.7 wt%. Then all the four hydrogen atoms in a TS cage are substituted by four Be, Li or Sc atoms (lowest energy state is Singlet for all the three) with respective hydrogen uptake capacity of 6.19, 12.69 and 12.01 wt%. When all the four hydrogens in TS cage are substituted by four Ti atoms, clustering of Ti atoms occurs and the cage structure gets distorted and therefore not considered for H2 adsorption. H2 adsorption on one Be(doublet), Sc(triplet) and Ti(quartet) atom doped TS cage is thermodynamically favourable below 210, 160 and 320 K respectively at 1 atm. pressure. At room temperature, it is thermodynamically favourable at higher pressure also. Four Sc and Be atom doped TS cages are found to be thermodynamically suitable for hydrogen storage below 210 K at 1 atm pressure. It is also suitable at room temperature but at higher pressure. One as well as four Li atom doped TS cages are not suitable for hydrogen storage for the entire temperature and pressure range considered. Molecular dynamics simulations performed using atom centered density matrix propagation (ADMP) show that the loosely bonded H2 molecules fly away during the simulations.

Ultra high response for hydrogen gas on Pd–Augr-alloy@ZnO core-shell nanoparticles with Pd–Au gradient composition alloy core

Pd@ZnO core-shell nanoparticles (CS-NPs) have shown relatively low response and selectivity to hydrogen gas due to surface oxidation of the Pd core. To overcome this, Pd@Au@ZnO core-double shell nanoparticles (CDS-NPs) with an added Au shell layer between the Pd core and ZnO shell are fabricated via a two steps hydrothermal route. Each as-prepared Pd@Au@ZnO CDS-NP is composed of a cubic Pd core (particle size of about 13 nm), an inner Au shell layer (approximately 5 nm thick) and an outer ZnO shell layer (approximately 45 nm thick). After calcination at 500 °C, each Pd@Au CS-NP core becomes a gradient composition Pd–Au alloy NP, in which the inner is a Pd-rich alloy and the outer is an Au-rich alloy (that retains the core-shell structure). At an optimal working temperature of 300 °C, the Pd-Augr-alloy@ZnO sensor shows a high response (174) toward 100 ppm H2 gas, which is about 3 and 13 times higher than that demonstrated by Pd@ZnO and pure ZnO sensors, respectively. Moreover, the Pd–Augr-alloy@ZnO CS-NPs sensor presents with higher selectivity to hydrogen gas than to other gases. The excellent response and selectivity are the result of a synergistic effect between the catalytic and hydrogen adsorption properties of the gradient composition Pd–Au alloy core.

Adsorption properties of hydrogen with iron oxides (FeO, Fe2O3): A ReaxFF molecular dynamics study

The reactive dynamics simulation with a reactive force field is a potentially effective method for investigating large systems (>1000 atoms) and has been employed in this study to analyze the hydrogen adsorption on FeO and Fe2O3. The adsorption behavior of hydrogen on FeO and Fe2O3 substrates have been compared by calculating the adsorption amount, adsorption rate and adsorption energy. The adsorption process at different temperatures (300 K and 1173 K) and pressures (200, 300 and 400 molecules) have been studied respectively, and the influences of these factors on the adsorption type and adsorption mechanism are compared, which are defined mainly by analyzing the radial distribution function (RDF) of different systems. The results show that Fe2O3-H2 system has a lower adsorption energy of −1.86 Kcal/mol, and a higher temperature promotes the chemical adsorption, increasing the hydrogen bond length. The results provide references and ideas for hydrogen adsorption on iron oxides.

The hydrogen storage capacities of 4d transition metals in various boron systems

The hydrogen adsorption and storage properties of BxM2 (M = Y-Mo, RuAg, x = 5–8) have been researched in detail. In B5M2 systems, most of compounds can adsorb multiple H2 with high gravimetric density, and their maximum adsorption are energetically favorable under room temperature. The atom-centered density matrix propagation (ADMP) molecular dynamics simulations show that B5Y2, B5Zr2, B5Nb2, and B5Ru2 can adsorb 6–10 H2 within 1000 fs at 300 K, and their gravimetric density are still close to or even higher the target of US Department of Energy (DOE). However, in more than half of the B5M2 systems, some H2 tend to dissociate and bond atomically on transition atoms in the process of adsorption. With the increase of boron atoms, the dissociation of adsorbed H2 will decrease. In B7M2 and B8M2, all of the H2 are adsorbed in the molecular form. Due to reversible average adsorption energy, satisfactory gravimetric density, ambient operating condition, the B5Pd2, B6Pd2, B7Y2, B7Zr2, B7Pd2, and B8Y2 complexes are the most promising hydrogen storage materials.