Hydrogen Storage Medium Research Articles

Feasibility of Li decorated C8 carbyne ring as a promising hydrogen storage media. DFT study

This study takes a unique approach by simulating the hydrogen storage properties of a carbyne C8-ring molecule decorated with lithium atoms on its outer surface. The simulations used the Density Functional Theory (DFT) formalism with the GGA-PBE functional in the Biovia Materials Studio Dmol3 modeling and simulation program. The results revealed that a maximum of 4 H2 molecules were physisorbed per Li atom, with an average binding energy of 0.22 eV/H2. This physisorption led to a gravimetric capacity of 7.25 wt.% and a volumetric capacity of 0.046 kg H2/L. The thermal stability and desorption temperature of LiC8-4H2 were determined by Molecular Dynamics calculations and the Van´t Hoff equation, showing that hydrogen molecules were easily desorbed at room temperature T= 300 K. These findings highlight the potential of Li-decorated carbyne as a promising material for hydrogen storage with applications in fuel cells.

Alkali Metal‐Doped Fullerenes as Hydrogen Storage—A Quantum Chemical Investigation

AbstractThe quest for alternative energy sources has been spurred by the drawbacks and environmental risks of fossil fuels, with hydrogen emerging as a viable contender. But finding materials that can effectively store hydrogen with the best adsorption energy is a major obstacle to building a hydrogen‐based economy. As a result, a significant amount of research has been conducted worldwide to examine fullerene's (C60) potential for hydrogen adsorption. The results of extensive DFT calculations are presented here, pertaining to the adsorption of hydrogen molecules onto fullerenes doped with alkali metals, namely Rubidium (Rb), Ceasium (Cs), and Fransium (Fr). The study analyzes a number of parameters, such as global properties, electronic, optical, and surface annihilation energy. These analyses are performed using the Gaussian 09 simulation package with the 6–31G/B3LYP level of theory DFT methodology. The findings show that an exothermic process is involved in the adsorption of hydrogen onto fullerene doped alkali elements, as evidenced by the negative adsorption energy. The attractive interactions between the polarized dipole of hydrogen molecules and the surface dipole of doped fullerenes can be the cause of this exothermicity. These results imply that fullerenes decorated with alkali metals are promising as likely hydrogen storage media.

Rapid hydrogen enclathration and unprecedented tuning phenomenon within superabsorbent polymers

Clathrate hydrate has emerged as a potentially viable storage medium for efficient hydrogen storage, owing to its eco-friendly characteristics and high hydrogen storage capacity. However, it is essential for its practical application to address the challenges posed by harsh thermodynamic formation conditions and slow formation kinetics for hydrogen hydrate. Here, we introduce the utilization of superabsorbent polymers (SAPs) as a dispersion matrix for tetrahydrofuran (THF) solutions to develop a method for rapid hydrogen enclathration. We investigated two distinct synthetic pathways, solution-borne and hydrate-borne routes. We also explored the relationship between hydrogen uptake/storage capacity, varying THF solution concentration within SAPs, and synthetic pathways for binary THF–hydrogen hydrates. The hydrogen storage capacity after 200 min enclathration reaction was relatively low for 1.0 mol% THF cases but significant for 5.56 mol% THF cases in hydrate-borne route (around 20 mmol H2/mol water), highlighting its potential for hydrogen storage material. The spectroscopic analysis revealed that the tuning phenomenon in THF 1.0 mol% hydrate was only observed in the solution-borne route, which facilitated hydrogen enclathration in partially vacant large cages of sII hydrates. It was striking that the tuning phenomenon was also observed in THF 5.56 mol% hydrate synthesized in both solution-borne and hydrate-borne pathways. Through phase equilibria measurements, we confirmed that less than 5.56 mol% of THF participated in forming binary hydrates. The different water and THF absorbability of SAPs resulted in a non-uniform distribution of THF solution within SAPs, causing the unprecedented tuning phenomenon. These findings provide valuable insights into the potential of SAPs for rapid hydrogen enclathration media, emphasizing the importance of understanding synthetic pathways and solution absorption properties for optimized hydrogen storage.

Superlight Ambient Temperature Reversible Hydrogen Storage Media Based on Alkali and Alkali Earth Metal-Functionalized 2D Square-Octagon BCN Monolayer.

Energy has always been the engine of human beings; however, because of the environmental pollution caused by traditional fossil fuels, the development of more sustainable energy resources is urgently needed. The hydrogen storage medium is essential for its realization. Here, we introduce a hydrogen storage material, a two-dimensional (2D) square-octagon BCN (SO-BCN) monolayer, composed of lightweight elements (B, C, and N) and strategically functionalized with alkali and alkali earth metal atoms (Li, Na, Mg, and K). Notably, Li@SO-BCN and Mg@SO-BCN exhibit exceptional reversible hydrogen storage capabilities, surpassing the DOE standard of 5.5 wt %, with gravimetric capacities of 7.129 wt % and an impressive value of 11.656 wt %, alongside low adsorption energies of -0.21 eV/H2 and -0.268 eV/H2 at room temperature, respectively. Our investigation, which combines analysis of the atomic structure, electronic structure, and hydrogen process, reveals distinct mechanisms at play: Li activates the substrate, creating additional adsorption sites on the SO-BCN monolayer. Compared with Li, the functionalization of Mg atoms not only activates SO-BCN via charge transfer but also allows Mg2+ to act as a potent attractor for H2 molecule adsorption. This work provides both promising candidates for future hydrogen storage media based on 2D monolayers and a design paradigm for next-generation hydrogen storage materials, emphasizing the synergy of electron-donating species, substrate activation, and hierarchical porous structures.

Efficient ammonia conversion in proton conducting fuel cells: Combined application of dendritic anodes and nanofiber catalysts

Ammonia, with its high hydrogen content, serves as an optimal carbon-free medium for indirect hydrogen storage, making it ideal for fuel cells. Nevertheless, the limited anodic catalytic activity of Proton-conducting solid oxide fuel cells (PCFCs) significantly hampers NH3 utilization efficiency and overall performance. This study introduces efficient nano-catalysts deposited onto dendritic anodic microchannels, leading to the formation of an in-situ ammonia decomposition reactor for internal ammonia gas conversion. Compared to conventional cells, this cell, equipped with a catalyst bed, shows a 25% increase in peak power density and a 20%–30% enhancement in NH3 utilization efficiency. Additionally, ammonia undergoes efficient decomposition on anodic metallic nickel, which prevents nickel nitridation and improves cell stability. The augmented stability of these cells is evidenced by their prolonged operational lifespan under constant current conditions, extending from 63 to 108 h, thus marking a substantial enhancement in the system's durability and reliability.

Reversible hydrogen storage with Na-modified Irida-Graphene: A density functional theory study

Two-Dimensional carbon-based materials as a potential hydrogen storage medium have attracted great attention. In this study, various key aspects such as structure, electronic properties, stability, and hydrogen storage performance of Na-modified Irida-Graphene (IG) were thoroughly investigated using density functional theory (DFT) calculation methods. The calculation results show that the binding energy of Na atoms with the substrate is 1.51 eV, far exceeding the cohesive energy. The AIMD results reflect the good thermal stability of the model. One Na atom can adsorb up to 5H2 molecules. The IG loaded with eight Na atoms on both sides can adsorb 32H2 molecules, achieving a hydrogen storage capacity of 7.82 wt%, far exceeding the US DOE target of 5.5 wt%. The calculated Van ’t Hoff equation indicates a desorption temperature of 248 K for the model. Moreover, reversible hydrogen storage can be achieved at medium to low pressures, with desorption temperatures ranging from 285 K to 417 K. These results suggest that Na-Modified IG models are candidate materials for reversible hydrogen storage under near-ambient conditions.

(Invited) Long-Term Sustainability through Carbon Dioxide Capture and Conversion: The Methanol Economy

Renewable methanol synthesized from carbon dioxide capture and conversion using water and renewable energies such as solar, wind, geothermal, atomic, etc., is a simple solution in the long run to a complex climate change carbon conundrum. Liquid methanol is a versatile high octane, clean burning automotive and marine fuel (to replace gasoline and diesel), a fuel for direct oxidation methanol fuel cell, chemical feedstock to make ethylene, propylene and myriad of other chemicals and a convenient hydrogen storage medium that can replace fossil fuels in almost all applications without inflicting major changes to the existing infrastructure. For a one carbon global CO2 problem, renewable CH3OH is a one carbonglobalsolution.

Lithium-modified B3C2P3 monolayer as a promising medium for reversible hydrogen storage

Although two-dimensional (2D) materials have been extensively studied as hydrogen storage media, the search for 2D materials with high hydrogen storage capacity and reversible hydrogen storage properties at room temperature remains challenging. In this context, B3C2P3 monolayer with Li modification is studied systematically by first-principles calculation. We find that Li-modified B3C2P3 monolayer can achieve a high hydrogen storage capacity of 8.99 wt% with an average adsorption energy of −0.23 eV/H2. Three of the H2 molecules are adsorbed around the Li atom, while the fourth H2 molecule is adsorbed above the buckled P atom due to the constricted space around the Li atom. Not only metal Li atoms but also the buckled substrate plays an important role in hydrogen adsorption, indicating that buckled 2D materials are more interesting and promising in hydrogen storage than flat 2D materials. The average desorption temperature (TD) calculated by van't Hoff formula is 293.84 K, which is very close to room temperature. In addition, at room temperature, the structure of hydrogen adsorption is stable at a low pressure of 3.21 MPa, suggesting a broad application prospect of in reversible hydrogen storage.

The augment effects of magnesium hydride on the lipid lowering effect of atorvastatin: an in vivo and in vitro investigation.

There is strong evidence connecting increased serum lipid levels to cardiovascular disorders, including atherosclerosis. Statins is prescribed as the primary medication to decrease lipid levels. Recent research has demonstrated that hydrogen possesses anti-inflammatory and antioxidant properties by modulating the expression of peroxisome proliferator-activated receptor gamma coactivator-1α, ultimately leading to the preservation of lipid homeostasis. Magnesium hydride (MgH2) is a prolonged stable hydrogen storage medium, which can be utilized to investigate its synergistic lipid-lowering effect with statins and its detailed molecular mechanism, both in vivo and in vitro. To ascertain the safety and efficacy of MgH2, we executed a comprehensive research of its influence on both physiological and pathological metrics. We noted a substantial diminution in lipid levels when MgH2 was integrated with atorvastatin, as attested by oil red staining. Furthermore, we scrutinized the regulatory effect of MgH2 on cytochrome P450 3A, which is a metabolic enzyme of statins, and discovered that it could be reduced by the MgH2. Concluding from our results, we propose that MgH2 inhibits the expression of cytochrome P450 3A in the liver and exerts an auxiliary lipid-lowering effect by increasing the blood concentration of statins. By augmenting our comprehension of MgH2's role in ameliorating lipid metabolism, we aspire to develop more promising therapies in the future.

First-principles investigation of Irida-graphene decorated with alkali metal for reversible hydrogen storage

Irida-graphene (IG) is a novel stable graphene allotrope, which exhibits metallic property. Based on first principles calculations, the potential of IG decorated with alkali metal atoms in reversible hydrogen storage has been investigated. Compared with graphene, IG has stronger binding on alkali metal atoms. For Li, Na, and K decorated IG, the polarization mechanism plays a crucial role in the adsorption of H2, the adsorption energies of H2 are −0.286, −0.209 and −0.183 eV/H2, and the hydrogen gravimetric densities can reach 7.1, 7.8 and 5.2 wt%, respectively, indicating that K decorated IG is not suitable as a hydrogen storage medium. The desorption temperatures calculated are 365 K and 267 K for stored H2 on Li/IG and Na/IG, respectively, and ab inito MD simulation suggest that Li/IG and Na/IG are stable at high temperature, thus Li and Na decorated IG have the potential application for reversible hydrogen storage.

Effect of Ce0.6Zr0.4O2 nanocrystals on boosting hydrogen storage performance of MgH2

Magnesium hydride (MgH2) has been widely recognized as a highly promising solid-state media for hydrogen storage. However, the high operating temperature and the intrinsic sluggish kinetics hinder the practical application as a portable solid storage carrier. To address this issue, we have successfully fabricated a novel rare earth-containing bimetallic oxide additive, namely Ce0.6Zr0.4O2 nanocrystals, which exhibits a significant catalytic effect in enhancing the hydrogen storage properties of MgH2. By incorporating 7 wt% Ce0.6Zr0.4O2 into MgH2, the modified composite releases hydrogen as low as 201 °C. Furthermore, in an isothermal dehydrogenation test conducted at 270 °C for 8 min, approximately 6.15 wt% of H2 was desorbed. The composites can rapidly recharge hydrogen at a low temperature of 50 °C and 6.02 wt% H2 being absorbed within 3 min at 150 °C under 50.0 bar. Comparatively, the dehydrogenation activation energy of the Ce0.6Zr0.4O2-modified MgH2 significantly decreased compared to MgH2 by ball milling. In addition to its improved hydrogen storage properties, the composite also exhibits excellent cycling stability. Through cyclic de-/rehydrogenation experiments conducted at 270 °C, a capacity retention of 98.9 % was achieved over 20 cycles. This exceptional performance can be attributed to the in-situ formation of the CeH2.73/CeO2-x and ZrO2, which originated from the Ce0.6Zr0.4O2 additive following the first de-/rehydrogenation cycle. The uniform dispersion of the multiphase component nano-sized active species within the MgH2 matrix facilitates charge transfer and accelerates hydrogen diffusion. Density functional theory calculations revealed the dissociation energy barrier and dissociation energy of H2 were alleviated by integrating Zr into CeO2. This work provides valuable insights for further rational designs of novel catalysts by transition metals and rare earths in promoting the commercialization of MgH2.

Ball Milling Innovations Advance Mg-Based Hydrogen Storage Materials Towards Practical Applications.

Mg-based materials have been widely studied as potential hydrogen storage media due to their high theoretical hydrogen capacity, low cost, and abundant reserves. However, the sluggish hydrogen absorption/desorption kinetics and high thermodynamic stability of Mg-based hydrides have hindered their practical application. Ball milling has emerged as a versatile and effective technique to synthesize and modify nanostructured Mg-based hydrides with enhanced hydrogen storage properties. This review provides a comprehensive summary of the state-of-the-art progress in the ball milling of Mg-based hydrogen storage materials. The synthesis mechanisms, microstructural evolution, and hydrogen storage properties of nanocrystalline and amorphous Mg-based hydrides prepared via ball milling are systematically reviewed. The effects of various catalytic additives, including transition metals, metal oxides, carbon materials, and metal halides, on the kinetics and thermodynamics of Mg-based hydrides are discussed in detail. Furthermore, the strategies for synthesizing nanocomposite Mg-based hydrides via ball milling with other hydrides, MOFs, and carbon scaffolds are highlighted, with an emphasis on the importance of nanoconfinement and interfacial effects. Finally, the challenges and future perspectives of ball-milled Mg-based hydrides for practical on-board hydrogen storage applications are outlined. This review aims to provide valuable insights and guidance for the development of advanced Mg-based hydrogen storage materials with superior performance.

Stone-Wales defective C60 fullerene for hydrogen storage

Hydrogen energy is one of promising non-polluting and renewable energy sources. In this paper, we present a first principal study of hydrogen storage in pure C60 fullerene cage and Stone-Wales (SW) defective C60 cages using density functional theory (DFT) with applying both the exchange functional B3LYP and the dispersion correction wb97xd at 6–31+g(d,2p) basis set. In addition, the counterpoise correction is applied, and the basis set superposition error is calculated. The calculations underscore that the hydrogenation binding energy of C60 cages occurs through an endothermal process for C60Hin with a hydrogen binding energy of 0.09 eV and through an exothermal process for C60Hout, C60SW66Hout, and C60SW65Hout, cages with hydrogen binding energies of −2.17 eV, −2.96 eV, and −2.20 eV, respectively. Remarkably, for the first time, the intermediate hydrogen binding energy is found inside C60SW66Hin fullerene, and C60SW65Hin fullerene cages with energies of −0.26 eV and −0.81 eV, respectively. The hydrogen adsorption inside the cavity of C60SW66 fullerene cage is thermodynamically possible below 289.8 K and entire pressure range considered. Our results highlight, for the first time, that the endohedral cavity of C60SW66 is a promising new medium for hydrogen storage due to its binding energies (−0.26 eV) and its hydrogen storage weight percentage (5.3%) that are close to the optimal conditions specified by DOE for commercial use. In addition, this study opens up a new discovery of Stone-Wales defective C60 fullerene for further endohedral cavity applications.

Hydrogen storage methods by lithium borohydride

This paper addresses the urgent need for efficient hydrogen storage methods in the context of combating climate change and transitioning to sustainable energy sources. Among various storage options, LiBH4 is highlighted for its high volumetric and gravimetric energy densities, critical factors in determining its suitability for energy applications. However, challenges arise due to its high thermolysis temperature, which poses difficulties, especially in applications like automotive use where high temperatures are required. The commercial viability of LiBH4 remains a significant obstacle due to the nascent stage of chemical hydride technology and the absence of large-scale production facilities. Environmental concerns also loom large, as the production of LiBH4 relies on extensive mining of lithium and boron, known for their environmental impact. Furthermore, the economic feasibility of LiBH4 as a hydrogen storage medium is questioned, given the substantial portion of total expenses attributed to hydrogen costs, affecting all methods except those based on fossil fuels or electricity. Nevertheless, there is optimism that with technological advancements and improved infrastructure, the costs associated with LiBH4 and hydrogen storage overall may decrease over time.In conclusion, while LiBH4 presents promising energy density characteristics, its practical implementation faces challenges such as high production costs, environmental concerns, and technological limitations. Overcoming these obstacles is crucial for realizing a sustainable and carbon-free energy landscape driven by hydrogen.

Molecular dynamics simulation of hydrogen adsorption and diffusion characteristics in graphene pores

Carbon structures have been shown to be potentially efficient hydrogen storage media, but the micro adsorption/diffusion kinetic properties of hydrogen storage are still unclear. We investigated the adsorption of H2 in carbonaceous nanoporous by molecular dynamics simulations. It was found that the hydrogen molecules were completely adsorbed when the pore size was 1 nm, and existed in both adsorbed and free forms when the pore size was 2–6 nm, and the adsorption was in a saturated state, with the absolute adsorption amount keeping constant. Modification of functional groups on the inner side of graphene pores reduces the hydrogen storage capacity, and this effect becomes more and more obvious with decreasing pore size, especially for 1 nm pores. The total adsorption amount of H2 in 1 nm graphene pores was 0.01315 × 10−3 mol/m2, which was 3.8846 times that of graphene oxide pore. The hydrogen adsorption effect on different surfaces is: G > GO(-O-) > GO(-OH) > GO(-O-/OH). The results of this study are helpful to further understand the physical adsorption mechanism of molecular hydrogen on carbonaceous materials.

Effect of precooling the in-charged on the performance of hydrogen storage systems packed with typical kinds of adsorbents

Selecting suitable adsorbents and managing the thermal effect are two important aspects on the practical application of the hydrogen storage system by adsorption. In this research, three kinds of promising adsorbents, which include MOF-5, MIL-101(Cr) and activated carbon AX-21, were selected for evaluating the effect of pre-cooling of hydrogen in-charged into a 0.5 L cylindrical vessel experimentally and numerically as per the temperature fluctuation, heat generated, accumulated amount of the charge under the flow rate of hydrogen required by an on board 5 kW PEMFC power unit. The validation of the prediction accuracy of the model was performed by the experiments conducted respectively at 77.15 K and 298.15 K where the vessel was packed with MIL-101(Cr). Simulations were further performed to evaluate the performance of the vessel respectively packed with three kinds of adsorbents within the flow rate range 15–40 L min−1 and temperature range 77.15–298.15 K. Results show that precooling the hydrogen in-charged is conducive to weakening the temperature fluctuation of the storage system, and heat from adsorption is the main factor affecting the accumulated amount of charge and the temperature fluctuation within the hydrogen storage system. It suggests that MOF-5 is a more suitable hydrogen storage medium than MIL-101(Cr) and AX-21, and charging the system with hydrogen precooled at 77.15 K under a smaller flow rate is beneficial to improving the performance of the storage system.

Integration of Green Hydrogen Production and Storage via Electrocatalysis.

Hydrogen economy, which proposes employing hydrogen to replace or supplement the current fossil-fuel-based energy economy system, is widely accepted as the future energy scheme for the sustainable and green development of human society. While the hydrogen economy has shown tremendous potential, the associated challenges with hydrogen production and storage remain significant barriers to wide applications. In light of this consideration, the integration of green hydrogen production and storage through electrocatalysis for direct production of chemical hydrogen storage media has emerged as a potential solution to these challenges. Specifically, through electrocatalysis, CO2 and H2O can be converted into methanol or formic acid, while N2 or NO x along with H2O can be transformed into ammonia, streamlining the hydrogen economy scheme. In this Perspective, we provide an overview of recent developments in this technology. Additionally, we briefly discuss the general properties and corresponding production strategies via the electrolysis of these chemical hydrogen storage media. Finally, we conclude by offering insights into future perspectives in this field, anticipating that the successful advancement of such technology will propel the development of the hydrogen economy toward practical implementation.

Enhanced H2 storage in silicene through lithium decoration and single vacancy and Stone‐Wales defects: A density functional theory investigation

AbstractDefect engineering and metal decoration onto 2‐D materials have gained major attention as a means of creating viable hydrogen storage materials. This Density Functional Theory (DFT) based study presents lithium decorated single vacancy (SV) and Stone‐Wales (SW) defective silicene as a viable media for storing hydrogen via physisorption. Introducing defects increases the Li adatom's binding energy from −2.36 eV in pristine silicene to −3.44 and −2.73 eV in SV and SW silicene, respectively, preventing Li adatom clustering. The presence of defects and Li adatom further aid hydrogen adsorption onto the substrates with binding energies present between the US‐DOE set range of −0.2 to −0.7 eV/H2 with the highest binding energy measured to be −0.389 eV/H2. The enhanced H2 binding energies are a result of a combined contribution of the Li(p) and Li(s) orbitals with the H(s) orbital with an indirect electronic transfer from the silicene substrate to the Li adatom. Upon double side Li decoration, both the Li‐decorated defective systems were able to effectively store multiple H2 molecules up to 28 H2 with the highest gravimetric density being 5.97 wt%. Ab Initio molecular dynamic simulations conducted at 300 K and 310 K confirm the stability of the Li adatom as well as the adsorbed H2 molecules at room temperature and establish the viability of these systems as effective, high gravimetric density, physisorption‐based hydrogen storage media.

Direct methanol oxygen-ion conducting solid oxide fuel cell with an integrated in-situ cracking reactor

Methanol, as an indirect hydrogen storage medium rich in hydrogen, is considered an ideal fuel for fuel cells. Oxygen-ion conducting solid oxide fuel cells (O-SOFCs) powered by methanol are renowned for their high energy conversion efficiency and minimal environmental impact, offering broad application prospects. However, challenges to their stable power generation arise from the rate of hydrogen production through methanol decomposition at the anode and carbon deposition on nickel-based anodes. To address these issues, this study explores the optimal operating temperature and concentration of methanol as an O-SOFCs fuel, while also developing a novel cell design. In this design, an in-situ cracking reactor for internal conversion of methanol is constructed by loading Ru-GDC high-efficiency nanofiber catalysts on dendritic anode microchannels, significantly enhancing the cell's power generation performance. Experimental results demonstrate that at 800 °C and a 30 % methanol concentration, the system increases the maximum power density (MPD) from 0.622 W cm−2 to 0.893 W cm−2, exhibiting a 43.57 % increase in power density and a 13.03 % improvement in methanol utilization. Additionally, the system effectively mitigates carbon deposition and nickel anode deactivation, thereby enhancing the cell's operational stability.

Computational evaluation of Li-decorated [formula omitted]C3N2 as a room temperature reversible hydrogen storage medium

We theoretically devised a novel complex by decorating Li atoms on the α-C3N2 for hydrogen storage, employing first-principles calculations. The findings reveal that: Li can be securely adsorbed onto the α-C3N2; the Li@α-C3N2 exhibits commendable thermal stability and boasts an excellent electronic structure due to the sp2 hybridization, making it highly conducive to hydrogen adsorption; the Li@α-C3N2 can adsorb 12 H2, achieving a capacity of 5.7 wt%; the average adsorption energy (0.215 eV ∼ 0.228 eV) falls within reversible hydrogen-storage range; the corresponding desorption temperature ranges from 277 K to 293 K. Additionally, the storage capacity of the Li@α-C3N2 can be as high as 5.7 wt% at 300 K and 10 bar. The adsorption mechanism can be attributed to a combination of electrostatic interactions, orbital interactions and van der Waals interactions between the substrate and hydrogen molecules.