Storage Of Molecular Hydrogen Research Articles

Hydrogen adsorption and dissociation, together with a multifractal transition into graphene-based surfaces

Ab-initio molecular dynamics simulations, together with multifractal detrended fluctuation analysis (MF-DFA) were used to study hydrogen adsorption into a five-vacancy graphene surface. This surface was chosen because it presents active bonds, due to a lack of carbon ions and may thus be appropriate for molecular hydrogen adsorption and storage. Hydrogen dissociation and chemical hydrogen adsorption, together with a multifractal transition were observed at the beginning of molecular dynamics simulations. Multifractal phase transition is a consequence of hydrogen dissociation and adsorption and was observed in the multifractal spectrum, as a fishtail-like behavior. Once the molecular hydrogen was adsorbed and dissociated, a weak multifractal spectrum was observed in time-series. Weak multifractal behavior was adduced by comparing to fractional Brownian motion (FBM). Multifractal characterization indicates irregular signals and anti-persistence, caused by temperature. A fractional Brownian motion region for forecasting and benchmarking, based on statistical indicators and multifractal characterization of the test region is proposed. The results obtained in this investigation may be significant in the search for surfaces and strategies for hydrogen storage.

Utilizing Nanostructured Materials for Hydrogen Generation, Storage, and Diverse Applications.

The rapid advancement of refined nanostructures and nanotechnologies offers significant potential to boost research activities in hydrogen storage. Recent innovations in hydrogen storage have centered on nanostructured materials, highlighting their effectiveness in molecular hydrogen storage, chemical storage, and as nanoconfined hydride supports. Emphasizing the importance of exploring ultra-high-surface-area nanoporous materials and metals, we advocate for their mechanical stability, rigidity, and high hydride loading capacities to enhance hydrogen storage efficiency. Despite the evident benefits of nanostructured materials in hydrogen storage, we also address the existing challenges and future research directions in this domain. Recent progress in creating intricate nanostructures has had a notable positive impact on the field of hydrogen storage, particularly in the realm of storing molecular hydrogen, where these nanostructured materials are primarily utilized.

Predictive Modeling of Molecular Mechanisms in Hydrogen Production and Storage Materials.

Hydrogen has been widely considered to hold promise for solving challenges associated with the increasing demand for green energy. While many chemical and biochemical processes produce molecular hydrogen as byproducts, electrochemical approaches using water electrolysis are considered to be a predominant method for clean and green hydrogen production. We discuss the current state-of-the-art in molecular hydrogen production and storage and, more significantly, the increasing role of computational modeling in predictively designing and deriving insights for enhancing hydrogen storage efficiency in current and future materials of interest. One of the key takeaways of this review lies in the continued development and implementation of large-scale atomistic simulations to enable the use of designer electrolyzer-electrocatalysts operating under targeted thermophysical conditions for increasing green hydrogen production and improving hydrogen storage in advanced materials, with limited tradeoffs for storage efficiency.

DFT study of Hydrogen storage capacity on Hf doped graphene

We explored the molecular hydrogen storage capacity of complex system with Hafnium doped graphene (Gr-Hf) using the Density Functional Theory (DFT) method. We efficiently adsorbed molecular six hydrogens on the Hf doped graphene surface. The quantum chemically calculated adsorption energy is found negatively in the range of - 344.433 Ry to -333.836 Ry this implies as increasing the adsorbed hydrogen molecule on hafnium doped graphene (Gr-Hf) sheet the adsorption energy decreases continuously. The binding energy of after adsorbing second hydrogen molecule too much larger than the next adsorbed H2 molecules i.e., the binding energy per hydrogen molecule highly decreases when we increase adsorbed atom (2.197 Ry in 2H2 to 1.048 Ry in 3H2) then small decreases for next adsorbed H2 molecules. The extracted binding energy found in the range 2.197 Ry to 2.120 Ry, fermi energy found minimum for 1H2 shows the minimum electron occupancy at the different energy levels. The fermi energy increases accordingly, the electron occupancy also increases and evaluates higher electron occupancy with fermi energy 2.850 eV for 6H2 and density of states (DOS) confirm the weak interaction between σ bonding electrons of H2 molecule with Hf doped graphene complex system. The proposed system opens a new insight for hydrogen storage-based devices.

Biodiversity and Potential Activity of Microorganisms in Underground Gas Storage Horizons

The share of molecular hydrogen as a source of “green energy” is currently significantly increasing. It is proposed to use existing underground natural gas storage facilities to store large volumes of hydrogen. In Russia, depleted oil and gas fields (DOGFs) and deep aquifers are used for natural gas storage. The purpose of this work was to determine microbial diversity in DOGF and deep aquifers by cultural and 16S rRNA gene-based approaches and the effect of H2 on the growth of microorganisms from the underground gas storage (UGS) horizons. The composition of the microbial community inhabiting the formation water of the Peschano–Umetskoe depleted oil and gas reservoir was typical for microbial communities of oil reservoirs and included bacteria of the phyla Bacillota (Dethiosulfatibacter, Defluviitalea, Acetobacterium, Syntrophobotulus), Actinobacteriota (Dietzia, Rhodococcus), Spirochaetota (Sphaerochaeta), Pseudomonadota (Shewanella), and Bacteroidota (Petrimonas), together with methanogenic archaea of the phylum Euryarchaeota (Methanobacterium). In some formation water samples, the share of methanogens of the genus Methanobacterium reached 61.6% of the total community; these hydrogen-utilizing organisms may contribute to the formation of methane in the reservoirs used for the storage of molecular hydrogen. Microbial communities of UGSs located in aquifers were less diverse and abundant. Cultivable hydrogenotrophic sulfate-reducing, homoacetogenic, and methanogenic prokaryotes were retrieved from the studied aquifers and from the DOGF used for gas storage. Microorganisms present in the condensation and reservoir waters of the UGS facilities can influence the composition of the water and gas phase, and affect the host rocks and borehole equipment.

Molecular hydrogen storage in binary H2-CH4 clathrate hydrates

Clathrate hydrate has emerged as a promising candidate for hydrogen storage, but the major challenge is the high pressure required for its formation. The addition of natural gas can significantly reduce the formation pressure, but also can improve the energy density. In this work, we estimated the hydrogen storage capacity of the H2-CH4 binary hydrate by performing the first-principles calculations and simulations. The thermodynamical and mechanical stability of the hydrate was studied as a function of the cage occupancy of both 512 and 51264 cages. For the most stable structure, the molar ratio of H2 and H2O is 0.353:1. The H2-CH4 binary hydrate can maintain its structure during dynamics under the moderate temperature and pressure. The self-preservation effect was observed at ∼270 K, which can be used for the hydrogen storage and transport. These findings provide a better understanding of the mixed hydrate as a viable hydrogen storage technology, which could enable us to achieve a sustainable hydrogen economy.

Hydrogen storage using novel graphene-carbon nanotube hybrid

Hydrogen storage is an active area of research particularly due to urgent requirements for green energy technologies. In this paper, we study the storage of hydrogen gas molecules in terms of physical adsorption on a carbon-based nanomaterial, i.e., a novel graphene-carbon nanotube hybrid. The novel carbon nanostructures were prepared from pristine nanotubes and graphene sheets using molecular dynamics simulations and hydrogen storage quantified in terms of gravimetric capacity was simulated using grand canonical Monte Carlo Simulations. We found the highest storage capacity of 5.90 wt% at room temperature and 100 bar with high reversibility of operation.

Y decorated all-boron B38 nanocluster for reversible molecular hydrogen storage: A first-principles investigation

Using first-principles calculations, the adsorption and storage of hydrogen molecules on Y decorated B 38 fullerene (Y 4 @B 38 ) are investigated. It is shown that Y atoms strongly attach to the hexagon cavities of B 38 , and that isolated Y atoms on B 38 are energetically more stable than the Y 4 cluster, hence avoiding the aggregation issue. Moreover, Y 4 @B 38 weakly interact with each other to build larger clusters. Polarization effects, as well as the Kubas mechanism, play essential roles in H 2 adsorption and storage on Y 4 @B 38 . The adsorption energy per H 2 molecule on Y 4 @B 38 ranges from −0.180 to −0.249 eV, which is within the recommended range for an optimal H 2 storage material. Each Y atom in Y 4 @B 38 may hold up to six H 2 molecules, corresponding to a gravimetric density of 4.96%. The stability of H 2 adsorbed structures and its dependence on temperature and pressure are evaluated using the modified van't Hoff equation. • Y atoms are strongly adsorbed on the hexagon cavities of B 38 . • The gravimetric density of hydrogen molecules on Y 4 @B 38 is 4.96%. • The effects of temperature and pressure are studied by the modified van't Hoff equation. • Clustering of Y 4 @B 38 fullerenes has a minor influence on H 2 storage capacity.

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 %.

Aromatic Clusters as Potential Hydrogen Storage Materials

The scientific community is engrossed in the thought of a probable solution to the future energy crisis keeping in mind a better environment-friendly alternative. Although there are many such alternatives, the green hydrogen energy has occupied most of the brilliant minds due to its abundance and numerous production resources. For the advancement of hydrogen economy, Government agencies are funding pertinent research projects. There is an avalanche of molecular systems which are studied by several chemists for storing atomic and molecular hydrogens. The present review on molecular hydrogen storage focuses on all-metal and nonmetal aromatic clusters. In addition to the effect of aromaticity on hydrogen trapping potential of different molecular moieties, the importance of using the conceptual density functional theory based reactivity descriptors is also highlighted. Investigations from our group have been revealing the fact that several aromatic metal clusters, metal doped nonmetal clusters as well as pure nonmetal clusters can serve as potential molecular hydrogen trapping agents. Reported systems include N4Li2, N6Ca2 clusters, Mgn, and Can (n = 8–10) cage-like moieties, B12N12 clathrate, transition metal doped ethylene complexes, M3+ (M = Li, Na) ions, E3-M2 (E = Be, Mg, Al; M = Li, Na, K) clusters, Li3Al4− ions, Li decorated star-like molecules, BxLiy (x = 3–6; y = 1, 2), Li-doped annular forms, Li-doped borazine derivatives, C12N12 clusters (N4C3H)6Li6 and associated 3-D functional material, cucurbiturils, lithium–phosphorus double-helices. Ni bound C12N12 moieties are also reported recently.

Glycerol Hydrogenolysis to Produce 1,2-Propanediol in Absence of Molecular Hydrogen Using a Pd Promoted Cu/MgO/Al2O3 Catalyst

The catalytic process of glycerol hydrogenolysis to produce 1,2-propandiol (1,2-PD) in the absence of external hydrogen addition has been investigated. The methanol present in the crude glycerol from a biodiesel production process is used to provide in situ hydrogen produced via methanol steam reforming for the glycerol hydrogenolysis process. This process can reduce the additional cost for the transportation and storage of molecular hydrogen and also reduce the safety risks related to using high hydrogen pressure. It was found that the introduction of Pd onto a Cu/MgO/Al2O3 catalyst significantly improved the glycerol conversion and 1,2-PD selectivity. The pseudo-first-order kinetic results suggested that the promoting effect of Pd is primarily attributed to the enhanced activity for the hydrogenation of acetol, which is the intermediate formed via glycerol dehydration. A 27−3 fractional factorial design experiment was carried out to investigate the impacts of seven single factors and their binary effects on two responses, namely 1,2-PD selectivity and glycerol conversion. The results showed that the glycerol feed concentration has the most significant effect on the 1,2-PD selectivity, such that the 1,2-PD selectivity is lower if a more concentrated glycerol is used as the feedstock; stirring speed, inert gas pressure and water to methanol molar ratio have insignificant effects on the reaction system. The addition of Pd, higher temperature and higher catalyst loading are the essential factors in order to obtain a high selectivity of 1,2-PD and a high glycerol conversion.

A triptycene derived hypercrosslinked polymer for gas capture and separation applications

AbstractThis work describes facile synthesis of a porous polymeric material (T‐HCP) using readily available reagents. Specifically, T‐HCP is a thermally stable and hypercrosslinked polymer (HCP) that is essentially microporous with a high BET specific surface area (940 m2 g−1). Triptycene based polymers are known to feature internal free volume. Thus, the incorporation of triptycene units and extensive crosslinking by an external cross‐linker in T‐HCP makes it a promising adsorbent for small gas capture applications. Experimental results show that T‐HCP demonstrated good CO2 capture capacity of 132 mg g−1 (273 K, 1 bar). Molecular hydrogen storage capacity of T‐HCP is estimated to be 17.7 mg g−1 (77 K, 1 bar). T‐HCP revealed high CO2/N2 selectivity (up to 63) as well as promising CO2/CH4 (up to 9.1) selectivity suggesting its potential applicability for CO2 separation from flue and natural gases.

The 2‐Propanol Fuel Cell: A Review from the Perspective of a Hydrogen Energy Economy

The 2‐propanol fuel cell has been shown to hold several key advantages over the more established methanol fuel cell, including a comparably high real open‐circuit voltage, reduced fuel crossover through a Nafion membrane and a benign toxicological fuel profile. In addition, while the highly selective partial oxidation of 2‐propanol to acetone in a fuel cell (rather than the more typical complete combustion of organic fuels to CO2) has been viewed as a disadvantage in the past, recent work has shown that the 2‐propanol/acetone couple is compatible with traditional hydrocarbon liquid organic hydrogen carrier (LOHC) systems though transfer hydrogenation. With this approach, a disadvantage of hydrogen LOHC logistics—the steep energy cost of dehydrogenation that must be provided during energy‐lean times—can be largely avoided. This LOHC compatibility along with the potential for high fuel‐cell performance could place the 2‐propanol fuel cell (also referred to as the direct isopropanol fuel cell or DIFC) in a position to enable a hydrogen energy economy while avoiding the drawbacks of molecular hydrogen transport and storage. In this Review, the purpose is to ascertain the state‐of‐the‐art of DIFCs—an understudied yet promising research area with unique advantages and challenges.

Be2+ and Mg2+-decorated sulflower: Potential systems for molecular hydrogen storage

The hydrogen binding efficiency of multiple metal-ion (Be2+, Mg2+)-decorated “First Generation” Sulflower (C16S8) systems has been investigated for the first time using density functional ω-B97XD method and 6311++G(d,p) basis set. Our calculations show that the central ring of the aforesaid system can be decorated by a single di-positive metal ion, followed by favorable decoration of at most one pair of metal ions (di-positive each) on the peripheral five-membered rings, both on same and opposite faces with certain preferences. All of the metal ion-decorated complexes are capable of efficient hydrogen binding. Be2+ and Mg2+-decked single ion complexes effectively bind six and four H2 molecules respectively. Moreover, each of the double ion-decorated systems can adsorb ten H2 molecules irrespective of the facial orientation of the metal ions. The average interaction energy (ΔE) between sulflower and metal ions (single and double ions) as well as the average binding energy (ΔBE) per molecular hydrogen of the concerned metal-ion-decorated complexes is found to be much higher for Be2+-decked systems. The nature of interaction between hydrogen molecules and metal ions is explicated by the topological analysis (AIM Analysis) and NBO formalisms. In case of Be2+-decked systems, the amount of charge transfer from H2 bonding orbital to metal anti-bonding orbital is much higher than analogous Mg2+-decorated systems. The Natural Population Analysis (NPA) evaluates the charge variation on the acceptor metal ions due to hydrogen adsorption. In short, our theoretical study gives a comprehensive account of the relationship between the metal ion-decorated sulflower systems and hydrogen molecules, which will further motivate researchers in the field of efficient hydrogen storage materials.

Ambient Condition Alcohol Reforming to Hydrogen with Electricity Output

“Hydrogen economy” could enable a carbon-neutral sustainable energy chain. However, issues with safety, storage, and transport of molecular hydrogen impede its realization. Alcohols as liquid H2 ca...

Theoretical DFT study on metal–organic frameworks for hydrogen storage

The cluster approach has been applied to mimic metal–organic framework (MOF) structures formed by 1,4-benzenecarboxylate linkers and metal cation connectors. The geometry optimizations are carried out at B3LYP/6-31G* level followed by frequency calculations. It was found that the replacement of OBe46+ connectors with OMg46+ (or OZn46+) ones leads to an increase in both the unit-cell sizes and basicity of oxide sites making them more potential for molecular hydrogen storage applications. Within the selected secondary building units (larger cluster models), the above replacement does not lead to an alteration on conduction and valence bands as well as in the resulting bandgap values. Bottleneck point of these structures is due to the presence of the so-called “central bulk” fourfold coordinated tetrahedral oxide anion site. The latter can be efficiently removed via replacement to “distorted cubic core” by introducing ZnTi3O46+ or MgTi3O46+ connectors which can be further replaced by MgSi3O46+ units. The all threefold coordinated O3C sites formed act as potential adsorption sites for incoming hydrogen molecules. Two-layer ONIOM (MP2/6-31G*: HF/3-21G) calculations have shown that the binding energies of molecular hydrogen lie within 5.5 and 5.3 kJ/mol for the MOF structures with MgTi3O46+ and MgSi3O46+ connectors, respectively.

Light metal functionalized two-dimensional siligene for high capacity hydrogen storage: DFT study

In this work, the hydrogen storage capacities of two-dimensional siligene (2D-SiGe) functionalized with alkali metal (AM) and alkali-earth metal (AEM) atoms were studied using density functional theory calculations. One AM (Li, Na, K) or AEM (Be, Mg, Ca) atom was placed on the 2D-SiGe surface, and several H2 molecules were placed in the vicinity of the adatom. The results demonstrate that the most favorable siligene site for the adsorption of Li, Na, K and Be atoms is the hollow site, while for the Mg and Ca atoms is the down site. The AM atoms are the only ones with considerable binding energies on the SiGe nanosheets. Pristine 2D-SiGe slightly adsorbs one H2 molecule per hollow site and, therefore, it is not suitable for hydrogen storage. In some of the AM- and AEM-decorated 2D-SiGe, several hydrogen molecules can be physisorbed. In particular, the Na-, K- and Ca-functionalized 2D-SiGe can adsorb six hydrogen molecules, whereas Li and Mg atoms adsorbed three hydrogen molecules, and the Be adatom only adsorbed one hydrogen molecule. The complexes formed by hydrogen molecules adsorbed on the analyzed metal decorated 2D-SiGe are energetically stable, indicating that functionalized 2D-SiGe could be an efficient molecular hydrogen storage media.

Whole-cell biocatalysis for hydrogen storage and syngas conversion to formate using a thermophilic acetogen

BackgroundIn times of global climate change, the conversion and capturing of inorganic CO2 have gained increased attention because of its great potential as sustainable feedstock in the production of biofuels and biochemicals. CO2 is not only the substrate for the production of value-added chemicals in CO2-based bioprocesses, it can also be directly hydrated to formic acid, a so-called liquid organic hydrogen carrier (LOHC), by chemical and biological catalysts. Recently, a new group of enzymes were discovered in the two acetogenic bacteria Acetobacterium woodii and Thermoanaerobacter kivui which catalyze the direct hydrogenation of CO2 to formic acid with exceptional high rates, the hydrogen-dependent CO2 reductases (HDCRs). Since these enzymes are promising biocatalysts for the capturing of CO2 and the storage of molecular hydrogen in form of formic acid, we designed a whole-cell approach for T. kivui to take advantage of using whole cells from a thermophilic organism as H2/CO2 storage platform. Additionally, T. kivui cells were used as microbial cell factories for the production of formic acid from syngas.ResultsThis study demonstrates the efficient whole-cell biocatalysis for the conversion of H2 + CO2 to formic acid in the presence of bicarbonate by T. kivui. Interestingly, the addition of KHCO3 not only stimulated formate formation dramatically but it also completely abolished unwanted side product formation (acetate) under these conditions and bicarbonate was shown to inhibit the membrane-bound ATP synthase. Cell suspensions reached specific formate production rates of 234 mmol gprotein−1 h−1 (152 mmol gCDW−1 h−1), the highest rates ever reported in closed-batch conditions. The volumetric formate production rate was 270 mmol L−1 h−1 at 4 mg mL−1. Additionally, this study is the first demonstration that syngas can be converted exclusively to formate using an acetogenic bacterium and high titers up to 130 mM of formate were reached.ConclusionsThe thermophilic acetogenic bacterium T. kivui is an efficient biocatalyst which makes this organism a promising candidate for future biotechnological applications in hydrogen storage, CO2 capturing and syngas conversion to formate.

Crumpled graphene as a hydrogen storage media: Atomistic simulation

The storage of molecular hydrogen in a 3D realistic carbon structure — crumpled graphene under various conditions is investigated by molecular dynamics. The action of hydrostatic pressure and temperature are systematically investigated. It is revealed that the capacity of hydrogen storage of the crumpled graphene can be extended by decreasing the temperature and increasing the applied hydrostatic pressure. These results suggest possibilities in controlling the hydrogen storage of crumpled graphene and highlight the influence of hydrostatic compression and temperature for the dehydrogenation process.

Si2BN monolayers as promising candidates for hydrogen storage.

Hydrogen storage properties of the pure Si2BN monolayer were studied using density functional theory calculations. The interaction of H2 molecules with the Si2BN monolayer is weak and of electrostatic nature. The average hydrogen adsorption energies are within the ideal range of practical applications (0.187-0.214 eV), and the consecutive adsorption energies indicate that the spontaneous adsorption of H2 molecules on the Si2BN monolayer can occur. The hydrogen gravimetric density of the periodic Si2BN monolayer reaches 8.5 wt%, which exceeds the standard of 6.0 wt% set by the US Department of Energy (DOE) by the year 2020. The estimated desorption temperatures show the desirable properties for the long term recycling of the Si2BN storage medium. Thus, our results show that the Si2BN monolayer is a promising candidate for molecular hydrogen storage.