Structure and hydrogen absorption properties of Ti53Zr27Ni20(Pd,V) quasicrystals

The structure and hydrogen absorption properties of Pd and V doped TiZrNi quasicrystals were investigated in terms of the equilibrium vapor pressure of hydrogen, and the results were compared with those of undoped samples. Rapidly quenched Ti₅₃Zr₂₇Ni₂₀ alloys formed quasicrystals and absorbed hydrogen H/M (hydrogen to host metal atom ratio) value of 1.79 at room temperature. This was attributed to their structure, which contains mostly tetrahedral interstitial sites that are chemically formed by atoms having a high affinity with hydrogen. However, the relatively low equilibrium vapor pressure of hydrogen, 0.14 Torr at 300 °C, prevents TiZrNi quasicrystals for the practical application on energy storage materials. To overcome this limitation, we replaced Ti with Pd and V to increase the vapor pressure of hydrogen and investigated the properties of hydrogen absorption behaviors. Results of XRD measurements revealed that the quasicrystal structure was maintained by the replacement of Ti with a maximum of 8 at. % of Pd and V. Total amounts of the absorbed hydrogen decreased from 1.33 to 1.06 and to 1.12 of the H/M values when the Ti was replaced by 8 at. % of Pd and V, respectively, at 300 °C. The pressure-composition-temperature data measured using an automatic gas-handling system revealed that the equilibrium vapor pressure increased from 0.14 to 0.21 and to 0.56 Torr at H/M value of 0.5 when Ti atoms were replaced by 8 at. % Pd, and V, respectively, without the appearance of an impurity phase. Our results demonstrate that the replacement of Ti with Pd and V is an effective method to increase the equilibrium vapor pressure of hydrogen without a phase transformation in a TiZrNi quasicrystal system.     

Dissociative adsorption of hydrogen and methane molecules at high-angle grain boundaries of pipeline steel studied by density functional theory modeling

Pipelines provide an economic and efficient means for hydrogen transport, contributing to accelerated realization of a full-scale hydrogen economy. Dissociative adsorption of hydrogen molecules (H₂) occurring on pipe steels generates hydrogen atoms (H), potentially resulting in hydrogen embrittlement of the pipelines. This is particularly important for existing pipelines transporting hydrogen in blended form with methane (CH₄). In this work, a density functional theory model was developed to investigate the dissociative adsorption of H₂ and CH₄ at high-angle grain boundaries (HAGB), a typical type of hydrogen traps contained in steels, and the stable adsorption configurations. Results demonstrate that the dissociative adsorption of both H₂ and CH₄ at the HAGB is thermodynamically feasible under pipeline operating conditions. Compared with crystalline lattice sites, the HAGB possesses the most negative free energy change, a lower energy barrier and the lowest H-adsorption energy, making the HAGB, especially the quasi three-fold site, become the most stable site for hydrogen adsorption. The saturation coverage of hydrogen at HAGB is calculated to be 1.33. The iron-H bonds are formed at the HAGB by charge consumption at Fe atoms and electron accumulation at H atoms, following a so-called electron hybridization mechanism. The CH₄ adsorption at HAGB affects the H₂ adsorption. Without pre-adsorption of CH₄, the hydrogen adsorption at the HAGB is more stable. Although an elevated CH₄ partial pressure decreases the thermodynamic tendency for H₂ adsorption, it cannot hinder occurrence of the H₂ dissociative adsorption.     

Ball-milling preparation of titanium/graphene composites and its enhanced hydrogen storage ability

Mass pure Ti/graphene (GE) composites have been synthesized by direct ball-milling Ti powders and GE nanosheets. Through adjusting the reaction conditions, Ti–C bonding in Ti/GE composites was constructed on the interface between Ti nanoparticles and GE nanosheets, which was also confirmed by the following Raman and XPS measurements. Pressure-composition-isotherm (PCT) curves showed that the Ti/GE composites exhibited a higher hydrogen storage capacity (4.3 wt% for H₂ at 300 °C, 0.08 bar) and lower equilibrium pressure compared with that of simply physically mixed sample. In addition, the hydrogen adsorption process and the mechanism for the Ti/GE composites have also been investigated, in which a Kubas-enhanced adsorption process was found in the composites. In this Kubas-type adsorption process, hydrogen was adsorbed firstly by Ti atoms with a formation of Ti–H bonding and then the bonded hydrogen was spilled over to graphene, forming a C–H interaction.     

Hydrogen adsorption on graphene sheets and nonporous graphitized thermal carbon black at low surface coverage

Behavior of hydrogen adsorption on nonporous carbon based materials was comparatively studied for selection of an efficient carrier for catalytic metals. Graphene sheets (GS) and graphitized thermal carbon black, which respectively has a specific surface area about 220 m²/g and 36 m²/g, were selected for adsorption equilibrium testes within temperature–pressure range from 77 K–87 K and 0–1 kPa. Henry law constants were employed to calculate the second virial constants and the limit isosteric heat of adsorption. The Weeks, Chandler and Andersen (WCA) perturbing scheme and the fundamental measure theory (FMT) were used to determine the interaction energy between solid atoms and hydrogen molecules. Adsorption potential well was determined by linear interpolation based on the Boltzmann distribution approximation. It shows that the potential well between hydrogen molecules and the GS, BP280 is respectively about 33.55 K and 31.97 K, suggesting that the bonding energy between the GS and hydrogen molecules is larger than that on carbon black.     

Electronic structure and hydrogen storage properties of Li–decorated single layer blue phosphorus

Single layer blue phosphorus (SLBP) is a promising two–dimensional material for nanoelectronic devices, but the electronic structure and hydrogen storage property of modified SLBP received little attention. Li atoms can be strongly bonded on SLBP in a 1:1 Li/P ratio with a binding energy larger than the cohesive energy of bulk Li. The geometric structure of SLBP suggests the 3s3p orbitals of the P atom hybridize in sp³ manner. But our analyses show that the 3s and 3p orbitals form bonding and antibonding orbitals respectively. The 3s orbitals are fully occupied as they have much lower energies, and the bonding orbitals formed by P 3p are occupied in pure SLBP. The decorated Li atoms transfer their 2s electrons to the antibonding orbital formed by P 3p. The Li atoms exist as +1 cations and they are ionically bonded on SLBP. H₂ molecules adsorbed on the Li⁺ cations are strongly polarized and form strong adsorption. When two H₂ are adsorbed on each Li atom decorated at the 1:1 Li/P ratio, the hydrogen storage capacity reaches 9.52 wt% but the H₂ molecules are arranged in two layers with the adsorption energy ?0.168 eV/H₂. When the Li atoms are decorated alternatively on the two sides of the P₆ rings with a Li/P ratio of 1:2, each Li atom can absorb two H₂ molecules in a single–layer; the hydrogen storage capacity is 5.48 wt% and the adsorption energy reaches ?0.227 eV/H₂. These results mean the Li–decorated SLBP can work at ambient temperature with high reversible hydrogen storage capacity.     

Surface adsorption and encapsulated storage of H2 molecules in a cagelike (MgO)12 cluster

Cluster-based materials are candidate materials for solid-state hydrogen storage owing to their special geometric and electronic structures. The surface adsorption and the encapsulated storage of H₂ molecules in a cagelike (MgO)₁₂ cluster have been studied using density functional theory (DFT) calculations including a dispersion interaction. The results revealed that the cagelike (MgO)₁₂ cluster surface can adsorb 24 H₂ molecules with an average adsorption energy of 0.116 eV/H₂, which brings about a gravimetric density of 9.1 wt%. Compared with dispersion-corrected DFT calculations, the traditional DFT method substantially underestimates the surface adsorption strength. According to symmetric configurations, a maximum capacity of six H₂ molecules can be stored in the interior space of the cagelike (MgO)₁₂ cluster. The encapsulated H₂ molecules are trapped by stepwise energy barriers of 0.433–2.550 eV, although the storage is an endothermic process. The present study will be beneficial for hydrogen storage in cagelike clusters and assembled porous materials.     

Storing-hydrogen processes on graphene activated by atomic-vacancies

We investigated the minimum energy pathways and energy barriers of reversible reaction (V₁₁₁ + H₂?V₂₂₁) based upon calculations using density functional theory. We find a comparable activation barrier of around 1.3 eV for both the dissociative chemisorption and desorption processes. The charge transfer rate from a reacting hydrogen atom to the graphene is around 0.18 e per hydrogen atom in the final state. A subsequent reaction path to recover the initial structure of V₁₁₁ is realized by the migration of hydrogen atoms from V₂₂₁ onto the graphene surface. The comparable energy barrier of 1.3 eV for both adsorption and desorption suggests that this novel storage and release concept has the potential to act as a hydrogen storage system for certain applications.     

Structural,electronic and spectral properties referring to hydrogen storage capacity in binary alloy ScBn (n = 1–12) clusters

Based on the DFT calculations within GGA approximation, we have systematically studied the ScB_n (n = 1–12) clusters and their hydrogen storage properties. The results show that the maximal adsorption for H₂ molecules is ScB₇ 6H₂ structure with the hydrogen storage mass fraction about 9.11%. For ScB_n·mH₂ clusters as n = 7 or 9–12, the average binding energies between 0.202 and 0.924 eV are suggestively conducive to hydrogen storage. In these medium clusters, the moderate adsorption strength can benefit application of hydrogen energy owning to easily adsorption and dissociation on H₂ molecules at room temperature and 1 bar pressure. Furthermore, the absorption spectrum is also investigated from TDDFT calculation. An obvious red-shift of spectral lines at 4.2 eV or 5.6 eV is detected with the increase of number of H₂ molecules. It can be regard as ‘fingerprint’ spectrum in experiment to indicate adsorption capacity of H₂ molecules for ScB_n·mH₂ nanostructures.     

Computational insights of alkali metal (Li / Na / K) atom decorated buckled bismuthene for hydrogen storage

The mechanism of hydrogen molecule adsorption on 2D buckled bismuthene (b-Bi) monolayer decorated with alkali metal atoms was studied using density functional theory based first principles calculations. The decorated atoms Li, Na and K exhibited distribution on surface of b-Bi monolayer with increasing binding energy of 2.6 eV, 2.9 eV and 3.6 eV respectively. The adsorption of H₂ molecule on the slabs appeared stable which was further improved upon inclusion of van der Waals interactions. The adsorption behaviour of H₂ molecules on the decorated slabs is physisorption whereas the slabs were able to bind up to five H₂ molecules. The average adsorption energy per H₂ molecules are in range of 0.1–0.2 eV which is good for practical applications. The molecular dynamics simulation also confirmed the thermodynamic stabilities of five H₂ molecules adsorbed on the decorated slabs. The storage capacity values are found 2.24 wt %, 2.1 wt %, and 2 wt %, for respective cases of Li, Na and K atoms decorated b-Bi. The analysis of the adsorbed cases pointed to electrostatic interaction of Li and H₂ molecule. The adsorption energies, binding energies, charge analysis, structural stability, density of states, and hydrogen adsorption percentage specifies that the decorated b-Bi may serve as an efficient hydrogen storage material and could be an effective medium to interact with hydrogen molecules at room temperature.     

Catalytic gasification of oil palm frond biomass in supercritical water using MgO supported Ni,Cu and Zn oxides as catalysts for hydrogen production

Non-noble metal supported catalysts such as 20NiO/MgO, 20CuO/MgO and 20ZnO/MgO were catalyzed the gasification of oil palm frond biomass in supercritical water for hydrogen production. All the catalysts are found to be pure with no impurities present. The specific surface area of these catalysts can be arranged in the order of 20NiO/MgO (30.1 m² g^–1) > 20CuO/MgO (16.8 m² g^–1) > 20ZnO/MgO (13.1 m² g^–1). Although catalysts with larger specific surface area are beneficial for catalytic reactions, in this study, the largest specific surface area did not lead to the highest catalytic performance. It is found that the 20ZnO/MgO catalyst (118.1 mmol ml^?1) shown the highest H₂ yield than the 20CuO/MgO (81.1 mmol ml^?1) and 20NiO/MgO (72.7 mmol ml^?1) catalysts. In addition, these supported catalysts also shown higher H₂ selectivity with reached 83.8%, 84.9% and 87.6% for 20CuO/MgO, 20NiO/MgO and 20ZnO/MgO catalysts. Other factors such as dispersion, basicity and bond strength play more important roles in supercritical water gasification of biomass to produce hydrogen.     

Hydrogen storage performance of platinum supported carbon nanohorns: A DFT study of reaction mechanisms,thermodynamics, and kinetics

Platinum (Pt) is one of a robust hydrogen dissociative catalyst. However, the migration of dissociated hydrogens from Pt nanoparticles to carbon supports such as graphene and carbon nanotube are energetically unfavorable reactions. To enhance the hydrogen storage via migration mechanism, carbon nanohorn is applied as a support for Pt nanoparticles (Pt and Pt₄). The H₂ storage performance of Pt and Pt₄ supported on the mono-vacancy carbon nanohorn (vNH) has been investigated by using density functional theory calculations. The Pt and Pt₄ firmly deposit at the vacancy site through the three strong Pt–C bonds with binding energies about ?7.0 eV, which can prevent the metal desorption and migration. The mechanism of H₂ storage starts with H₂ adsorption followed by H₂ spillover reaction. The calculation results reveal that the supported Pt nanoparticles are the active sites for H₂ dissociative adsorption while the high curvature surface of carbon nanohorn is the active area for accommodating the migrated H atoms from the spillover reaction. Remarkably, the hydrogen spillover reactions over Pt– and Pt₄-supported on vNHs in this study are spontaneous at room temperature with highly exothermic reaction energy. The fundamental understanding obtained from this study is beneficial for further design and synthesis of high-performance materials for H₂ storage applications.     

Nanoscale-mixed ZnNiCu hydroxide composite catalyst for improved photocatalytic hydrogen evolution

The advantage of a complex catalyst in which several catalysts are mixed is that the overall reaction rate can be efficiently increased by increasing each sub-reaction rate. Each constituent catalyst in the complex catalyst must be as well-mixed as possible—while maintaining high catalytic activity—owing to the short reaction time of these sub-reactions. This study reports a facile synthetic method to mix two catalysts homogeneously at the nanoscale while keeping their crystal structure intact. ZnNiCu hydroxide nanoplates with a mixed crystal structure composed of ZnNi and ZnCu hydroxides, which could promote H₂O dissociative adsorption and H₂ desorption, respectively, were synthesized by a simple cation exchange of ZnO nanoparticles and a precursor mixture of Ni and Cu. ZnNi and ZnCu hydroxides in the nanoplates were mixed at the nanoscale while maintaining their respective crystal structures; density functional theory calculations show that these structures could effectively perform H₂O dissociative adsorption and H₂ desorption, respectively, resulting in high activity in the overall photocatalytic hydrogen evolution reaction.     

Lithium clusters on graphene surface and their ability to adsorb hydrogen molecules

This research describes the theoretical study of the adsorption of lithium clusters on graphene and the ability to capture hydrogen molecules. The results of the studied structures showed that the [Li₁C₅₄H₁₈]⁺ system is capable of accepting three hydrogen molecules showing adsorption energies of 0.12 eV. On the other hand, it is important to note that in [Li_nC₅₄H₁₈] n = 2–6 systems, the lithium atoms that do not interact with the graphene surface, they can adsorb up to four hydrogen molecules. The [Li₆C₅₄H₁₈]4H₂ system presented a higher adsorption energy value of 0.31 eV. Finally, the Li–H₂ interactions were characterized by a NBO analysis, which showed that hydrogen atoms are the donors and lithium atoms are the acceptors.     

Thermodynamics of spontaneous dissociation and dissociative adsorption of hydrogen molecules and hydrogen atom adsorption and absorption on steel under pipelining conditions

While hydrogen pipelines have attracted increased attention, safety of the pipelines has been a concern in terms of hydrogen embrittlement (HE) occurring upon hydrogen atom (H) generation and permeation in the steels. In this work, thermodynamic analyses regarding H generation and adsorption on pipeline steels by two potential mechanisms, i.e., spontaneous dissociation and dissociative adsorption, were conducted through theoretical calculations based on Gibbs free energy change of the H generation reactions. Moreover, H adsorption free energy and configurations were determined based on density functional theory (DFT) calculations. Effects of H adsorption site, H coverage and hydrostatic stress on H adsorption and absorption were discussed. Spontaneous dissociation of hydrogen gas molecules to generate hydrogen atoms is thermodynamically impossible. Dissociative adsorption is thermodynamically feasible at wide temperature and pressure ranges. Particularly, an increased hydrogen gas partial pressure and elevated temperature favor the dissociative adsorption of hydrogen. Hydrogen atoms generated by dissociative adsorption mechanism can adsorb stably at On-Top (OT) and 2-fold (2F) Cross-Bridge sites of Fe (100), while hydrogen adsorption at 2F site is more stable due to a higher electron density and a stronger electronic hybridization between Fe and H. The influence of H atom coverage on dissociative adsorption occurs at low coverages only, i.e., 0.25–1.00 ML as determined in this work. External stresses make dissociative adsorption more difficult to occur compared with a fully relaxed steel. Both tetrahedral sites (TS) and octahedral sites (OS) can potentially host absorbed H atoms at subsurface of the steel. Absorbed H atoms will be predominantly trapped at TS due to a low energy path and exothermic feature. Diffusion of H atoms from steel surface to the subsurface is more difficult compared with the dissociative adsorption.     

Calcium-decorated graphdiyne as a high hydrogen storage medium: Evaluation of the structural and electronic properties

Graphdiyne (GDY) is a new member of carbon allotropes consisting of sp and sp² hybridized carbon atoms. In this work, the hydrogen adsorption on Calcium (Ca) decorated GDY and the influence of adatom on structural properties of GDY are investigated, using first principles plane wave calculations with Van der Waals corrections. The results show that similar to graphyne (GY) and unlike carbon nanotube (CNT), fullerene and graphene, clustering of Ca on GDY hinders due to the higher binding energy of the adatom to the carbon frame than the Ca cohesive energy. It can be seen that the Ca-decoration promotes hydrogen storage capacity of GDY, extremely (E_ads = ?0.266 and ?0.066 eV for Ca-decorated and pristine GDY, respectively). It is concluded that, the best site for the Ca trapping is 18-membered ring in which, Ca lies in-plane of GDY (E_ads = ?3.171 eV). Fourteen H₂ molecules (with the average adsorption energy of ～0.2 eV/H₂) can be adsorbed on the Ca atom from one side. The hydrogen storage capacity is estimated to be as high as 17.95 wt% for the both sides of GDY. So, the Ca-decorated GDY is offered as a promising candidate for hydrogen storage applications.     

Li-decorated porous graphene as a high-performance hydrogen storage material: A first-principles study

Development of novel carbon-based nanoporous materials with high reversible capacity and excellent cycling stability is a hot topic in the field of hydrogen delivery and storage. In this work, first-principles calculations are carried out to discuss the hydrogen storage properties of Li-decorated porous graphene (Li-PG). The binding energies, electronic structures, storage capacities of hydrogen on different sites are investigated in details. The computational results show that with the increase of lithium doping concentration, the electron concentration of donor atoms exceeds the N_c value, and as a consequence, the PG changes from the p-type semiconductor to the n-type degenerate semiconductor. The maximum hydrogen adsorption configurations of H1a-H'1b and H2a-H'2b systems are obtained, and the average binding energy of per H₂ molecule is 0.245 eV and 0.263 eV, respectively. Furthermore, ab inito MD simulation results show that the H1-H'1 and H2-H'2 systems can hold up to sixteen and fifteen H₂ molecules, which corresponds to a hydrogen storage capacity of 10.89 wt% and 10.79 wt% at T = 300 K (no external pressure), respectively.     

Modification of COF-108 via impregnation/functionalization and Li-doping for hydrogen storage at ambient temperature

Post-modification approaches such as Li-doping, impregnation, and functionalization are promising methods to enhance H₂ adsorption in metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs). In this work, we propose a two-step method to modify COF-108 with the aim to enhance its hydrogen storage capacity at ambient temperature. First, we geometrically modified COF-108 through C₆₀ impregnation or aromatic ring grafting. Subsequently, we surface doped the modified COF-108 with Li atoms. COF-108 is the lightest 3D crystalline material ever reported and it is a promising H₂ storage material. Our grand canonical Monte Carlo (GCMC) simulations demonstrated that the combination of Li-doping with C₆₀ impregnation or aromatic ring grafting can potentially increase the volumetric H₂ adsorption capacity of COF-108 to reach a total H₂ adsorption capacity close to the U.S. DOE target. One of the Li-doped C₆₀-impregnated (Li₆C₆₀) COF-108 (with 8 Li₆C₆₀ moieties impregnated) showed an absolute H₂ uptake beyond the 2010 DOE target (45.6 mg/g and 28.6 g/cm³) at 233 K and 100 bar. Impregnation of C₆₀ and/or grafting of aromatic rings not only increased the density of doped Li in the modified COF-108 but also created more overlapped potential interaction with H₂, which resulted in higher number of H₂ adsorption sites per unit volume as compared to the unmodified material.     

Degradation of Ni-Zr0.9Sc0.1O1.95 anode in H2 + H2O at low temperature: Influence of nickel surface charge

The present paper reports on the data of the Ni-Zr_0.9Sc_0.1O_1.95 anode polarization resistance long-term test (1500 h) at 600 °С in the wet hydrogen and 30% H₂ + 70% H₂O. The results are presented for two type of anodes: initial and impregnated with ceria. The fast degradation of both types of anodes in 30% H₂ + 70% H₂O was observed. After the long-term tests in 30% H₂ + 70% H₂O at 600 °C, heating and exposure at 900 °C in wet hydrogen leads to the restore of anode performance. At the termination of the 1500 h test, the area polarization specific resistance of Ni-Zr_0.9Sc_0.1O_1.95 remained almost unchanged as compared to the initial value, whereas for impregnated anodes the polarization resistance increased three times. The observed phenomena were explained by the OH^? ions adsorption at the positively charged nickel surface. During the long-term tests at 600 °С the electrode microstructure did not change and the significant sintering of highly disperse ceria was not observed.     

High capacity and reversible hydrogen storage on two dimensional C2N monolayer membrane

Searching advanced materials with high capacity and efficient reversibility for hydrogen storage is a key issue for the development of hydrogen as a clean energy. Here, we have explored the potential application of C₂N monolayer using as a promising material for hydrogen storage through a comprehensive density functional theory (DFT) investigation. Our calculational results indicate that hydrogen molecule can only form weak interaction on neutral C₂N monolayer with the adsorption energy of 0.06 eV. However, if extra charges (5 e^?) are introduced to the system, the adsorption energy of hydrogen molecule on C₂N will be dramatically enhanced to 0.27 eV. Moreover, once the extra charges are moved from the system, the adsorbed hydrogen molecule will be spontaneously released from C₂N monolayer without any barrier. Interestingly, the average adsorption energy for each of the 48 absorbed H₂ molecules is 0.28 eV with the charge injection (8 e^?). This adsorption energy meets the criterion of the Department of Energy (DOE) for hydrogen storage (0.2–0.6 eV). Moreover, C₂N has a high hydrogen storage capacity of 10.5 wt %. Overall, this investigation demonstrates that the new fabricated C₂N can be used as an efficient material for hydrogen storage with high capacity and reversibility by modifying the charges that it carried. The narrow band gap (1.70 eV) of C₂N also ensures the electrochemical methods can be easily realized in experiment.     

The reversible hydrogen storage abilities of metal Na (Li,K, Ca,Mg, Sc,Ti, Y) decorated all-boron cage B28

The density functional theory is used to study the hydrogen storage abilities of alkali metal Li (Na, K), alkaline-earth metal Mg (Ca), and transition metal Ti (Ti, Sc, Y) decorated B₂₈, which is the possible smallest all-boron cage and contains one hexagonal hole and two octagonal holes. The most stable structure of B₂₈ explored by the calypso search is as same as that explored by Zhao et al. [Nanoscale 7(2015)15086]. It is calculated that the hollow sites outside of the cavities should be the most stable for all metals except for Ti. The average adsorption energy of H₂ molecules (E_ad) adsorbed by each Na (Ca, K, Mg, Sc, Y and Li) atom outside of the B₂₈ cage are in the range from 0.2 to 0.6 eV, which is suitable for hydrogen storage under near-ambient conditions. However, the largest hydrogen gravimetric density (HGD) for the B₂₈Sc₃-12H₂ structure is smaller than the target of 5.5 wt% by the year 2017 specified by the US Department of Energy (DOE). Therefore, the metal Ti (Sc) decorated all-boron cage B₂₈ should not be good candidates for hydrogen storage. The calculated desorption temperature and the molecular dynamic simulation indicate that the B₂₈M₃-nH₂ (M = Na, Li, Ca, K, Mg, Y) structures are easy to desorb the H₂ molecules at the room temperature (T = 300 k). Furthermore, the B₂₈ cages bridged by the sp²-terminated B₅ chain can hold Na (Li, Ca, K, Mg, Y) atoms to capture hydrogen molecules with moderate E_ad and HGD. These findings suggest a new route to design hydrogen storage materials under the near-ambient conditions.