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[Display omitted] • A simple construction strategy is proposed for hierarchical porous foam carbon (NOAC-5 K-750). • NOAC-5 K-750 are prepared by the mild-homogeneous activation process under low precursor/KOH mass ratio (about 1: 0.8). • NOAC-5 K-750 has a high specific surface area (S BET = 1753 m2/g) with multistage nanopore structure. • NOAC-5 K-750 obtains an excellent H 2 storage density (2.92 wt%) and CO 2 capture capacity (5.28 mmol/g). Currently, carbon-based porous materials for hydrogen (H 2) storage and carbon dioxide (CO 2) capture are mostly applied at higher pressures (30–300 bar). However, applications for H 2 storage and CO 2 capture under ambient pressure conditions are significant for the development of portable, household, and miniaturized H 2 energy technologies. This demands a higher standard for the interface microenvironment of adsorbents. Derived from polyurethane foams (PUFs) solid waste, the hierarchical porous foam carbon with interpenetrating-type pore structures exhibits high specific surface area (S BET = 1753 m2/g), abundant oxygen and nitrogen functional groups, and a hierarchical nanopore structure (V Ultra = 0.232 cm3/g, V Micro = 0.628 cm3/g and V Meso = 0.186 cm3/g) through the mild-homogeneous sonication-assisted activation process. Under the limited adsorption of pore interface microenvironment composed by hierarchical nanopore structure and dipole-induced interaction (H(Ⅱ)-H(Ⅰ)···N/O and O(Ⅱ) = C(Ⅰ) = O(Ⅱ)···N/O), it exhibits an excellent H 2 storage density (2.92 wt% at 77 K, 1 bar) and CO 2 capture capacity (5.28 mmol/g at 298 K, 1 bar). This research approach can serve as a reference for the dual-functional design of porous foam carbon, and promote the development of adsorption materials for CO 2 capture and energy gas storage under ambient conditions. [ABSTRACT FROM AUTHOR]

Creating the porous Zinc-Zeolitic Imidazolate Framework (Zn-ZIF) using a solvothermal technique addresses the need for advanced materials with distinctive properties and cost-effectiveness in modern applications. The PXRD, SEM, UV-DRS, TEM, and TGA/DTG are used to characterize different concentrations of Zn-ZIF. Zn-ZIF's crystalline structure and phase purity have been verified by PXRD. Using diffuse reflectance spectra, the Kubelka-Monk function determined the band gaps of the Zn-ZIF samples, and scanning electron microscopy revealed a more porous structure. At 77 K and 1 bar, the Zn-ZIF solution with a 2:1 ratio had the highest hydrogen storage capacity (1.71 wt%). The electrochemical behavior of several Zn-ZIF electrodes in a 6 M KOH electrolyte was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments. The Zn-ZIF electrode with a 2:1 ratio exhibits a low charge transfer resistance and a high proton diffusion coefficient (D) of 1.687 × 10−4 cm2 s−1. The characteristics of the 2:1 synthesized Zn-ZIF electrode as a supercapacitor were investigated. Our analysis of the generated Zn-ZIF material's specific capacitance values after 2000 cycles revealed an impressive retention rate of nearly 89 %, with values of 296.6 Fg-1. In addition, we examined the photocatalytic activities of the as-synthesized material by exposing it to ultraviolet light and seeing how it degraded organic dyes such as Cango-Red (CR) dye. With a photocatalytic efficacy of 95.06 % for CR dye, Zn-ZIF (2:1 ratio) is the most effective. These findings should provide new knowledge for researchers interested in developing novel Zn-ZIF materials for photocatalytic, energy storage, and hydrogen storage applications. [ABSTRACT FROM AUTHOR]

A series of superconducting samples including pure Bi2Sr2Ca2C3O10 (BSCCO), Pb-doped BSCCO (Bi1.35Pb0.65Sr2Ca2Cu3O10), Mg-doped BSCCO (Bi1.65Mg0.35Sr2Ca2Cu3O10), and optimally co-doped Pb-Mg-BSCCO with an optimal formula of BiPb0.65Mg0.35Sr2Ca2Cu3O10 (108K superconductor) were carefully synthesized and optimized with a maximum ratio of incorporated lead and magnesium, achieving both quality of structural features and an improved Tc offset of 108 K. The optimized porous sample was well characterized via x-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), and three-dimensional atomic force microscopy (3D-AFM). In addition, the Brunauer–Emmett–Teller (BET) specific surface area was estimated at 11.9 m2g−1. Porous Mg-doped BPSCCO exhibited high performance efficiency for H2 storage, recording maximum H2 uptake of 5.92 wt.% at a temperature of 270°C and pressure of 14 bar. A mechanism of loaded hydrogen was proposed. Magnesium and lead incorporated in 2223-BPSCCO were suggested to play a vital role in hydrogen storage as Mg hydride and Pb as plumbane. [ABSTRACT FROM AUTHOR]

Achieving net-zero carbon emissions by 2050 is imperative to mitigating the global climate crisis, necessitating a transition to sustainable energy sources. Hydrogen, recognized for its high energy density, is a promising sustainable fuel; however, its storage and transportation are challenging, necessitating the development of more effective storage materials. Metal–organic frameworks (MOFs) possess exceptional structural integrity and diversity, making them highly valuable in applications such as catalysis, separations, and energy storage. Despite their significant potential as viable materials for H2 storage, the poor packing of powdered MOFs limits their volumetric storage capacity. Improvement in packing density can be achieved by modifying the crystal shape and structure to reduce the void volume. In this paper, we embarked on synthesizing different nonideal crystal shapes and orientations by varying the ligand-to-metal ratio, which changes the overall crystal growth direction. We report the engineering of MIL-53-Al, focusing on tuning its crystal size and shape distribution to enhance its packing density and volumetric H2 storage capacity. This approach allows the synthesis of MOF nanomaterials with a high surface area (up to 1900 m2/g) and increased packing density (0.38 g/cm3), while preventing crystal damage when subjected to pressure compaction, thereby enhancing the volumetric storage capacity. After tuning, the volumetric storage capacity of the two best-performing samples, (MIL-53-Al)1:1 and (MIL-53-Al)0.52:1, exhibited a monoclinic crystal shape, which enhanced not only the overall packing density but also the working volumetric capacity of the system. Specifically, (MIL-53-Al)1:1 achieved an enhancement of 25% in working capacities compared to pristine MIL-53-Al. Moreover, its volumetric working capacity was estimated to be 37 g/L under the pressure swing (PS) conditions between 77 K/70 bar and 77 K/5 bar, surpassing the 30 g/L volumetric capacity of the compressed 700-bar pressure storage systems. [ABSTRACT FROM AUTHOR]

The study of novel materials for H2 storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H2 adsorption on Pd4-nNin (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was investigated using density functional theory calculations. First, the properties of Pd4-nNin (n = 0–3) clusters embedded on PNG were analyzed in detail. Then, the H2 adsorption on these composites was computed. The Eint between the Pd4-nNin (n = 0–3) clusters and the PNG was greater than that computed in the literature for Pd-based systems embedded on pristine graphene. Consequently, it was deduced that PNG can more significantly stabilize the Pd4-nNin (n = 0–3) clusters. The analyzed composites exhibited a HOMO–LUMO gap less than 1 eV, indicating good reactivity. Based on the Eads of H2 on Pd4-nNin (n = 0–3) clusters embedded on PNG, it was observed that the analyzed systems meet the standards set by the DOE. Therefore, these composites can be viable alternatives for hydrogen storage. [ABSTRACT FROM AUTHOR]

The safe, affordable, and eco-friendly storage of gases is a pressing environmental concern worldwide. Porous carbon, as a widely utilized adsorbent with a broad pore size distribution spanning from small micropores to large macropores, is unsuitable for the selective adsorption of gases with very small molecular size, such as hydrogen. Although this adsorbent is relatively low-cost, ordered porous carbons offer promising advantages by leveraging the advantages of carbon-based adsorbents to achieve uniform pore size distribution and high specific surface area, enabling more selective and rapid separation while minimizing pressure drop and allowing for easy regeneration. This work reviews the use of templated ordered porous carbons produced using hard templating with commonly employed templates, such as silica, zeolites, and open framework materials such as metal organic frameworks, for hydrogen storage applications. The synthesis methods and operating parameters that impact the properties of the final product are evaluated in this study, and a brief comparison with soft-templated carbons is also provided. Based on available literature, the hydrogen adsorption properties of hard-templated carbons are explored, including effective operating conditions and parameters and the underlying adsorption mechanisms. [ABSTRACT FROM AUTHOR]

Aluminum is the most abundant and promising material for hydrolytic hydrogen generation. It can be easily transported and stored. However, the oxide protective layer around Al limits its hydrolytic activity and hinders practical applications. To solve this problem, NaH is introduced to form the core-shell structure of Al-based NaH solid fuel powder by a simple hand mixing method in an open lab environment. The new core-shell structure of Al-based NaH solid fuel powder showed the best hydrolytic performance among Al-based materials and produced 98 % hydrogen yield at a 1 to 0.9 M ratio of NaH and Al in water. The hydrolytic activity consists of NaH hydrolytic splitting and Al hydrolysis. XRD and SEM analysis confirmed that NaH is the key to supporting complete Al hydrolysis and attaining maximum yield as compared to calcium hydride. Our research endorsed the practical implementation of inexpensive and transportable hydrolytic hydrogen generation materials and offered a new idea for the design of hydrolytic hydrogen generation materials for further development. [Display omitted] • Aluminum-based sodium hydride is cheap and transportable hydrogen generation material. • Aluminum hydrolyzes completely in the presence of NaH and produce 98 % yield. • Applicable for affordable hydrogen delivery systems to movable electronics devices. [ABSTRACT FROM AUTHOR]

In this study, a new porous organic polymer (KFUPM-CO2) with intrinsic nitrogen atoms as active sites for CO2 capture was optimized and synthesized via Friedel-Crafts alkylation of triptycene and 2,2-bipyridine. The porous polymer shows a high surface area of 1100 m2/g with a tuned microporosity of less than 1.2 nm, confirmed by NLDFT. KFUPM-CO2 showed a remarkable CO2 sorption capacity of 5.6 mmol/g at 273 K, 3.2 mmol/g at 298 K, and a pressure of 760 mmHg KFUPM-CO2 showed a high enthalpy of adsorption of 43.7 kJ/mol for CO2 with IAST selectivity of CO2/N2 of 127 at 273 K and 97 at 298 K on simulated flue gas composition. Additionally, KFUPM-CO2 exhibited an H2 storage capacity of 1.5 wt. % at 77 K and 860 mmHg Grand Canonical Monte Carlo (GCMC) simulations further revealed that KFUPM-CO2 was mainly stabilized by π-π intra-molecular interactions, and exhibited strong van der Waals attractions to CO2 molecules via the pyridyl nitrogen atoms, resulting in the rapid uptake. The combined advantages of binding 2,2-bipyridine with triptycene provided a robust porous polymer with abundant nitrogen sites, permanent porosity, and thermal stability, rendering KFUPM-CO2 an excellent candidate for CO2 capture and H2 storage technologies.

Hydrogen has emerged as a promising clean energy carrier for automobile applications. Magnesium hydride (MgH2) has garnered significant attention as a potential H2 storage material due to its high capacity and low cost. Nonetheless, its practical use is hindered by unfavorable H2 sorption kinetics and operating temperatures. This study presents a novel approach to enhance the H2 storage properties of MgH2 by adding graphene oxide (GO) supported tin dioxide (cSnO2) nanoparticles. The as-prepared catalysts (GO/SnO2) were synthesized through modified chemical methods followed by ball-milling with MgH2 characterized using various techniques, including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray and Fourier transform infrared spectroscopy (FTIR). The catalytic effect of GO-SnO2 nanoparticles on MgH2 was investigated through systematic H2 sorption studies as well as thermal analysis. Results demonstrate that the onset temperature for H2 desorption was significantly reduced, and the dehydrogenation kinetics were substantially enhanced. [ABSTRACT FROM AUTHOR]

In continuation of the previous part, this paper comprehensively focuses on energy, exergy, exergo-economic, and environmental (4E) analyses of two prioritized clean hydrogen (H 2) supply chains pathways. The first scenario relies on domestic demand , involves blue H 2 production and storage using steam methane reforming coupled with carbon capture and storage through H 2 conversion to hydrogen carriers in liquid form (ammonia and methanol) aligned with the existing infrastructure. The second scenario involves green H 2 production from photovoltaic panels as the power source follows by storing H 2 in liquid form which is more suitable to export. The findings indicate that the blue H 2 system outperforms the green H 2 system in terms of energy and exergy, boasting 41.38% and 22.15% compared to 12.16% and 12.75%, respectively. However, when examining economic parameters, the blue H 2 system shows a total cost rate of 1976 US$/h, a net profit of $747.2 million (mn) at the end of its lifetime, and a payback period of approximately nine years. Conversely, the green H 2 system demonstrates economic indicators of a 125.2 $/h as a total cost rate, $1.26 billion (bn) net profit, and an 8.17 year payback period. Moreover, the production cost rates for blue and green H 2 are 1.32 $/kg and 2.55 $/kg, respectively; while the CO 2 emissions rate in the blue H 2 system is 10.71 kg/s. The green H 2 system prevents 19.84 kg/s of CO 2 emissions resulted a significant environmental cost reduction of 2.28 $/kg H 2. This analysis facilitates a thorough comparison of these two clean H 2 production and storage systems, offering insights for policymakers across performance, economic, and environmental dimensions. • A comprehensive 4E analysis was applied for the selected H 2 value chain scenarios. • Blue H 2 scenario is superior economically while environmentally the green one takes precedence. • Carbon credit makes the green H 2 scenario emerges frontrunner utilizing PV solar technology. • Methanol was recognized as the most cost-effective H 2 carrier for storage in Iran. [ABSTRACT FROM AUTHOR]

Significant technological advancements have been made in the production and utilization of hydrogen (H 2) since 1990, marking the period when its potential as a fuel began to be widely recognized. However, for a hydrogen-based energy system to be viable, especially in the transportation sector, substantial improvements in H 2 storage technology are necessary. Various methods are available for supplying hydrogen to vehicles, including compressed or liquid hydrogen, metal hydrides, chemical storage, and gas adsorption on solid surfaces. Among these, gas-on-solid adsorption emerges as a highly efficient and safe method for storing hydrogen gas. This review briefly summarizes research on hydrogen adsorption using nanostructured adsorbents, such as carbon-based nanostructures (graphene, reduced graphene oxide, carbon nanotubes, carbon nitride, and other carbon nanostructures), metals and metal oxides, polymers, and metal-organic frameworks. Additionally, it covers new experimental and theoretical investigations into the hydrogen adsorption capabilities of metal hydrides. • This review briefly summarizes research on hydrogen adsorption using nanostructured materials. • New experimental and theoretical investigations into the hydrogen adsorption capabilities of metal hydrides are summarized. • Designing electrode materials for H 2 storage devices should focus on improving efficiency, capacity, and practicality. [ABSTRACT FROM AUTHOR]

The study of novel materials for H2 storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H2 adsorption on Pd4-nNin (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was investigated using density functional theory calculations. First, the properties of Pd4-nNin (n = 0–3) clusters embedded on PNG were analyzed in detail. Then, the H2 adsorption on these composites was computed. The Eint between the Pd4-nNin (n = 0–3) clusters and the PNG was greater than that computed in the literature for Pd-based systems embedded on pristine graphene. Consequently, it was deduced that PNG can more significantly stabilize the Pd4-nNin (n = 0–3) clusters. The analyzed composites exhibited a HOMO–LUMO gap less than 1 eV, indicating good reactivity. Based on the Eads of H2 on Pd4-nNin (n = 0–3) clusters embedded on PNG, it was observed that the analyzed systems meet the standards set by the DOE. Therefore, these composites can be viable alternatives for hydrogen storage.

LiAlH4 is a potential solid-state H2 storage material, where safe and efficient H2 storage is of critical importance for the transition towards a sustainable emission-free economy. To improve the H2 release and storage properties of LiAlH4, confinement in porous media decreases the temperature of H2 release and improves the kinetics, where considerably improved H2 release properties are accompanied by a loss in the total amount of H2 released. The capability of mesoporous carbon black to improve the H2 storage properties of confined LiAlH4 is investigated with temperature-programmed desorption and time-stability measurements using X-ray diffraction and N2 gas adsorption measurements to characterize the composite materials’ composition and structure. Here, we present the capability of commercial carbon black to effectively lower the onset temperature of H2 release to that of near-ambient, ≥295 K. In addition, the confinement in mesoporous carbon black destabilized LiAlH4 to a degree that during ≤14 days in storage, under Ar atmosphere and at ambient temperature, 40% of the theoretically contained H2 was lost due to decomposition. Thus, we present the possibility of destabilizing LiAlH4 to a very high degree and, thus, avoiding the melting step before H2 release at around 440 K using scaffold materials with fine-tuned porosities.

Lithium alanate (LiAlH 4) has high gravimetric capacity but its practical application is still severely constrained by poor reversibility and sluggish kinetics. In this study, the dehydrogenation behaviour of LiAlH 4 was modified with the inclusion of Zn 2 TiO 4. The initial temperature for the dehydrogenation of LiAlH 4 was downshifted to 111 °C (first dehydrogenation) and 151 °C (second dehydrogenation) with the inclusion of 10 wt% Zn 2 TiO 4. The as-milled LiAlH 4 released only 0.1 wt% H 2 while the LiAlH 4 –10 wt% Zn 2 TiO 4 sample released 3.6 wt% H 2 in 60 min at 90 °C which is 36 times faster than undoped LiAlH 4. The dehydrogenation activation energies for the first two dehydrogenation process was also reduced by 24.1 and 21.0% than as-milled LiAlH 4. The X-ray diffraction analysis revealed that the Zn 2 TiO 4 reacts with LiAlH 4 and the formed Al–Ti and Ti–Zn during the dehydrogenation leading to the superior dehydrogenation behaviour of LiAlH 4. • Zn 2 TiO 4 was successful prepared via a solid-state method. • Zn 2 TiO 4 additive decrease the onset desorption temperature of LiAlH 4. • The addition of Zn 2 TiO 4 also enhanced the desorption kinetics of LiAlH 4. • The E A for the two-dehydrogenation stages of Zn 2 TiO 4 -doped LiAlH 4 was reduced. • The new active species of Al–Ti and Ti–Zn play a synergistic role. [ABSTRACT FROM AUTHOR]

LiAlH4 is a potential solid-state H2 storage material, where safe and efficient H2 storage is of critical importance for the transition towards a sustainable emission-free economy. To improve the H2 release and storage properties of LiAlH4, confinement in porous media decreases the temperature of H2 release and improves the kinetics, where considerably improved H2 release properties are accompanied by a loss in the total amount of H2 released. The capability of mesoporous carbon black to improve the H2 storage properties of confined LiAlH4 is investigated with temperature-programmed desorption and time-stability measurements using X-ray diffraction and N2 gas adsorption measurements to characterize the composite materials' composition and structure. Here, we present the capability of commercial carbon black to effectively lower the onset temperature of H2 release to that of near-ambient, ≥295 K. In addition, the confinement in mesoporous carbon black destabilized LiAlH4 to a degree that during ≤14 days in storage, under Ar atmosphere and at ambient temperature, 40% of the theoretically contained H2 was lost due to decomposition. Thus, we present the possibility of destabilizing LiAlH4 to a very high degree and, thus, avoiding the melting step before H2 release at around 440 K using scaffold materials with fine-tuned porosities. [ABSTRACT FROM AUTHOR]

To address the growing demands for renewable energy storage and reduce carbon emissions to the environment, the search for safe and valuable energy storage systems is needed. The environment and human health are unaffected by using hydrogen as a fuel because it is clean, efficient, and environmentally benign. However, the absence of efficient hydrogen storage methods is one of the technical barriers to introducing hydrogen energy on a wider scale. Liquid organic hydrogen carriers (LOHCs) have been viewed as promising potential candidates for hydrogen storage because of their low cost, high hydrogen storage capacity, reversibility, and compatibility with existing energy supply infrastructures. However, associated with LOHCs, there are significant kinetic barriers in the reversible hydrogenation/dehydrogenation processes, which demands the use of effective catalysts. In this review, first-principles studies are given attention in recent activities in advancing the design of heterogeneous catalysts for the dehydrogenation of LOHC compounds—here, the designs include the use of supported catalysts and bimetallic catalysts—and determining the effect of the metal surface (facet dependence) on the mechanism of catalytic activity. The review concludes with a mention of some challenges, and outlook research directions for improved catalyst design in the dehydrogenation of LOHCs. • Review of the dehydrogenation of LOHC's developments, challenges, and prospects. • Focuses on improving the design of effective catalysts for dehydrogenation of LOHC. • LOHC is a promising option for clean and low-cost high hydrogen storage capacity. • First-principles insights on the design of supported and bimetallic catalysts. [ABSTRACT FROM AUTHOR]

The increasing energy demand, depleting fossil fuel reserves and increasing greenhouse gas emissions have initiated the search for cleaner and more affordable energy sources. Hydrogen is considered a major energy source due to its high calorific value. The physisorption of H 2 on a porous material is an attractive alternative for its storage. This paper presents a two-fluid equation-based model benchmarked against an experimental work on hydrogen storage in an activated carbon packed bed reported in the literature. The computational model is implemented in Ansys Fluent 21.1.0 to solve the hydrodynamic and thermal interaction between the gas and solid phases along with the mass transfer due to adsorption. Adsorption isotherm is calculated from the modified Dubinin-Astakhov (D-A) equation, while the resultant mass transfer is determined from the Linear Driving Force (LDF) model. These equations are incorporated into the model with the help of User Defined Functions (UDF). The predicted pressure, local bed temperature, and adsorption values show a good match with the experimental results. In addition, the sensitivity of different thermal and material properties revealed that a denser adsorbent bed and a high value of thermal properties improve the performance of the H 2 storage in the tank. [Display omitted] • H 2 adsorption in a porous media was simulated by coupled adsorption two-fluid model. • Temperature evolution, pressure, and absolute H 2 adsorption were predicted. • Thermal properties of the material played a crucial role in H 2 storage. • The bed porosity affected the adsorption process in the tank. [ABSTRACT FROM AUTHOR]

Because of the increasing demand for energy sources, searching for reversible and high-capacity hydrogen storage materials plays a vital role in the extensively utilizing of hydrogen as a clean energy source. In this study, dispersion-corrected density functional theory (DFT-D3) calculations are utilized to examine the possibility of storing H 2 molecules on Li, Na, and K alkali metals decorated C 6 O 6 Li 6 cluster. To evaluate H 2 adsorption capability, the adsorption energies, electron density difference iso-surfaces, and charge-transfers are calculated and discussed. The results indicate that a hydrogen molecule is physisorbed on the Li@C 6 O 6 Li 6 , Na@C 6 O 6 Li 6 , and K@C 6 O 6 Li 6 with average adsorption energies of −0.264, −0.150, and −0.109 eV, respectively. Double-sided alkali metal atoms decoration can lead to the maximum gravimetric density of 15.68, 14.49, and 13.79 wt% for 2Li@C 6 O 6 Li 6 –8H 2 , 2Na@C 6 O 6 Li 6 –10H 2 , and 2K@C 6 O 6 Li 6 –12H 2 complexes, respectively. Finally, desorption temperatures reveal that the systems can operate as reversible hydrogen storage materials. [Display omitted] • Alkali metal decorated C 6 O 6 Li 6 cluster for hydrogen storage using DFT-D3 calculations. • Double alkali metal decorated C 6 O 6 Li 6 cluster shows maximum gravimetric density above 10.00 wt%. • Adsorption capacities and desorption temperatures confirm H 2 storage reversibility. [ABSTRACT FROM AUTHOR]

Graphene nanoflakes are widely utilized as high-performance molecular devices due to their chemical stability and light weight. In the present study, the interaction of aluminum species with graphene nanoflake (denoted as GR-Al) has been investigated using the density functional theory (DFT) method to elucidate the doping effects of Al metal on the electronic states of GR. The mechanisms of the diffusion of Al on GR surface and the hydrogen storage of GR-Al were also investigated in detail. The neutral, mono-, di-, and trivalent Al ions (expressed as Al, Al+, Al2+, and Al3+, respectively) were examined as the Al species. The DFT calculations showed that the charge transfer interaction between Al and GR plays an important role in the binding of Al species to GR. The diffusion path of Al on GR surface was determined: the barrier heights of Al diffusion were calculated to be 2.1–2.8 kcal mol−1, which are lower than Li+ on GR (7.2 kcal/mol). The possibility of using GR-Al for hydrogen storage was also discussed on the basis of the theoretical results. [ABSTRACT FROM AUTHOR]

Activated carbon (AC), as an effective solid adsorbent, is extensively employed in H 2 and CO 2 storage. To enhance its adsorption capability and selectivity, it is necessary to increase its surface area and dope heteroatoms by a simple and environment-friendly method. In this work, nitrogen doped activated carbon (NAC) has been synthesized from sustainable biomass by direct activation with the assistance of melamine. The obtained NAC with 2.1 wt% N dopants possesses a high surface area (2477.27 m2/g) and pore volume (1.93 cm3/g). The NAC displayed enhanced H 2 uptake capacity (2.29 wt% at 77 K, 1 bar and 0.83 wt% at 298 K, 100 bar) and adequate CO 2 uptake capacity (2.85 mmol/g at 298 K, 1 bar and 4.49 mmol/g at 273 K, 1 bar). Activation mechanism with the assistance of melamine was proposed in accordance with the experimental data. The facile method of preparing NAC is potential for large-scaled production. [Display omitted] • NAC was prepared by direct activation of starch with the assistance of melamine. • Melamine enhanced the activation process of NaHCO 3 and doped N into NAC. • The H 2 uptake is up to 2.29 wt% at 77 K and 1 bar. • The CO 2 uptake is up to 4.49 mmol/g at 273 K and 1 bar. [ABSTRACT FROM AUTHOR]

In this article, newly designed 3D porous polymers with tuned porosity were synthesized by the polycondensation of tetrakis (4-aminophenyl) methane with pyrrole to form M1 polymer and with phenazine to form M2 polymer. The polymerization reaction used p-formaldehyde as a linker and nitric acid as a catalyst. The newly designed 3D porous polymers showed permanent porosity with a BET surface area of 575 m2/g for M1 and 389 m2/g for M2. The structure and thermal stability were investigated by solid 13C-NMR spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). The performance of the synthesized polymers toward CO2 and H2 was evaluated, demonstrating adsorption capacities of 1.85 mmol/g and 2.10 mmol/g for CO2 by M1 and M2, respectively. The importance of the synthesized polymers lies in their selectivity for CO2 capture, with CO2/N2 selectivity of 43 and 51 for M1 and M2, respectively. M1 and M2 polymers showed their capability for hydrogen storage with a capacity of 66 cm3/g (0.6 wt%) and 87 cm3/g (0.8 wt%), respectively, at 1 bar and 77 K. Molecular dynamics (MD) simulations using the grand canonical Monte Carlo (GCMC) method revealed the presence of considerable microporosity on M2, making it highly selective to CO2. The exceptional removal capabilities, combined with the high thermal stability and microporosity, enable M2 to be a potential material for flue gas purification and hydrogen storage.

[Display omitted] • Highly microporous activated carbons were synthesized through a unique method involving sacrificial templating of melamine followed by CsOH activation. • The resulting PMC sample demonstrates exceptional microporous characteristics, boasting a significantly high micropore surface area and micropore volume. • The highly microporous structure of the PMC facilitated significant CH 4 and H 2 uptake capacities. • The potential utility of PMC was validated through repeated adsorption–desorption cycling tests. • Our PMC demonstrated not only a high CH 4 adsorption capacity but also a decent CH 4 /H 2 selectivity. Achieving carbon neutrality necessitates advancements in adsorbent-based gas storage technologies, particularly for maximizing the utilization of natural gas (CH 4) and hydrogen (H 2) as sustainable energy sources. Activated carbons, characterized by their high surface area, stability, and cost-effectiveness, emerge as promising candidates for CH 4 and H 2 storage applications. Here, we report highly microporous activated carbons prepared using sacrificial templating of melamine followed by Cs+ ion activation. The resulting activated carbon demonstrates exceptional microporous characteristics, boasting a significantly high micropore surface area (2311 m2/g) and micropore volume (1.070 cm3 g−1). These structural attributes translate into impressive CH 4 (11.92 mmol/g at 298 K and 70 bar) and H 2 (2.74 mmol/g at 298 K and 70 bar) storage capacities, underscoring its potential as a viable ambient temperature gas storage material. Furthermore, our evaluation extends to the performance of the activated carbon for adsorptive CH 4 /H 2 separation. The activated carbon exhibits a notable CH 4 working capacity (3.13 mmol/g at 298 K, 1–10 bar pressure swing) coupled with a moderate Ideal Adsorbed Solution Theory (IAST) selectivity (25). These findings highlight the suitability of the activated carbon for both CH 4 and H 2 storage applications, as well as the separation of H 2 from CH 4. [ABSTRACT FROM AUTHOR]

Using abandoned reservoirs for geothermal energy development and H 2 storage is economical. The impact of complex fractures from long-term oil and gas extraction on geothermal energy and H 2 storage is not yet clearly understood. Here, a pressure small signals extraction and amplification (PSEA) technology is developed to improve reservoir monitoring accuracy. This technology is capable of coupling many pressure transient analysis models to invert parameters for multiple scenarios. This work establishes numerical models to simulate the effects of geothermal energy extraction and H 2 storage over 5000 days. Results show that this technology improves the accuracy of inverted parameters by 4–14 times. This technology adjusts the production temperature differences in a single injection-production system from 1.4K to 6.5K and the net heat power from 0.25 MW to 1.1 MW, and it can also identify an early low-rate H 2 storage phase. The Non-Sorting Genetic Algorithm II calculates that the PSEA technology brings economic benefits of $704,000 and $352,000 for geothermal energy extraction and H 2 storage in a single injection-production system. In conclusion, the developed monitoring technology and models improve accuracy in assessing geothermal energy development and H 2 storage, preventing failures in residential heating or H 2 storage projects. [Display omitted] • The PSEA technique improves the accuracy of the inversion parameters. • The PSEA technique corrects the geothermal energy production effect. • The PSEA technique identifies the early low-flow H 2 storage phase. • The NSGA-II algorithm confirms the PSEA technique's positive economic impact. [ABSTRACT FROM AUTHOR]

In this study, the influence of incorporating Co, Mo and Mn oxides into Pt/Al 2 O 3 catalyst on the dehydrogenation performance of Liquid organic Hydrogen Carrier (LOHCs) is investigated. A notable positive impact on the dehydrogenation process was observed, resulting in enhanced catalytic performance. This effect is associated with improved product desorption and a significant reduction in the by-product formation like methylfluorene. Particularly, the electron-acceptor effect exhibited by molybdenum, emerge as the key factor in enhancing catalytic performance. This effect allowed for the reduction of platinum content without compromising the productivity and selectivity and representing a significant advancement in catalyst design. These findings highlight the potential for Mo-based catalysts to serve as a promising alternatives to Pt-based catalysts in LOHC dehydrogenation processes. [Display omitted] • Mesoporous Pt(M)/Al 2 O 3 (M = Co, Mn, Mo) catalysts were synthesized using the incipient wetness impregnation method. • Adding a second metal effectively enhanced the dehydrogenation activity of the Pt/Al 2 O 3 catalysts. • High H 2 -chemisorption capacity and synergistic Pt-M interactions contributed to the superior activity of these catalysts. • Methyl-fluorene by-product concentration was found to be correlated with the concentration of full dehydrogenated H0-BT in the reaction medium. [ABSTRACT FROM AUTHOR]

Low-cost walnut shell-based carbons with high microporosity were prepared by simple one-step carbonization with chemical activation using KOH, exhibiting the promising potential to be a very good CO 2 and H 2 adsorbent. The physicochemical properties of the obtained carbons were characterized by N 2 and CO 2 adsorption isotherms, X-ray powder diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis. The activated carbon AC-800 was characterized by a highly developed specific surface area of 1868 cm2/g and a high micropore content of 0.94 cm3/g. It highly exhibited CO 2 uptake in 1 bar was up to 9.54, 5.17, 4.33 mmol/g for 0, 25 and 40 °C, respectively. In addition, the H 2 storage capacity was 3.15 mmol/g at 40 bars. Significantly, confirmed an exceptionally high dependency of CO 2 and H 2 uptake vs micropores structure of activated carbon. AC-800 also shows good selectivity for CO 2 /N 2 and fast adsorption kinetics that be easily regenerated with superior cyclic stability after multiple cycles The experimental isotherm data of activated carbon produced from walnut shells were analyzed using Langmuir, Freundlich, Temkin, Sips, and Toth isotherm equations. The fitting details showed that the multitemperature Toth equation is a powerful tool to mathematically represent CO 2 and H 2 isotherms on activated carbon. The easy way of preparation and high capture abilities endow this kind of activated carbon attractive as a promising adsorbent for CO 2 and H 2 storage. [Display omitted] • Walnut shells have been used successfully to synthesize AC. • AC display an appropriate micropore structure to achieve high H 2 and CO 2 adsorption capacity. • The mechanism of CO 2 and H 2 adsorption has been explained. • AC-800 had high CO 2 /N 2 adsorption selectivity and stability. • Sample AC-800 display great potential for low-temperature H 2 storage. [ABSTRACT FROM AUTHOR]

Porous carbons with pore sizes in the ultramicropore range (0.6–0.7 nm) are of great interest for hydrogen storage, transportation, and application as a clean energy source. In particular, when they are nanomaterials, their high surface-to-volume ratio maximizes H2 adsorption capacity. Existing ultramicroporous carbon materials are often in powder form and obtained by environmentally hazardous processes. Here, two highly ultramicroporous, self-supporting, and nanostructured 2D carbonaceous materials with high H2 sorption capacity were developed from poly-(vinyl alcohol) electrospun mats. The mats were stabilized by a heat treatment up to 195 °C, and subsequently, two strategies were followed: direct pyrolysis of the sample at 800 °C or application of an acidic activation treatment followed by pyrolysis. Both obtained materials showed high H2 adsorption capacity (6.48 and 11.47 mmol/g at 10 bar), similarly to or better than other materials reported in the literature, with the great advantage of being self-supporting. Moreover, both materials achieve complete desorption. Furthermore, the addition of the acidic activation enhances H2 adsorption capacity due to the greater ultramicroporous volume. This work will allow the development of a new range of ultramicroporous carbon materials obtained from green polymeric nanofibers for H2 storage. [ABSTRACT FROM AUTHOR]

Developing novel materials with high-capacity and reversible properties for storing hydrogen (H 2) is crucial for energy treatments. We here investigated comprehensively the H 2 storage performance of the Ca-decorated g-CN (Ca@CN) monolayers using first-principles calculations. The Ca atoms can be uniformly decorated into the center of the pores of g-CN monolayers without aggregation. The Ca@CN monolayer has an average H 2 adsorption energy of around 0.163–0.228 eV as well as high H 2 storage capacity of 10.1 wt%. The stabilities of the H 2 adsorption systems are confirmed by high hardness and low electrophilicity. The temperature of desorption is anticipated to be near the room temperature and ideal for fuel cell devices. The thermodynamic analysis along with desorption temperature reveal that the Ca@CN monolayer has promising potentials as reversible and high capacity hydrogen storage materials (HSM), which will motivate experimental efforts to synthesize the high-efficient HSM. [Display omitted] • H 2 storage properties of Ca-decorated-CN monolayer were studied using DFT+D methods. • Ca-decorated-CN monolayer is thermodynamically stable enough for Hydrogen storage. • Ca-decorated-CN monolayer stores 10.1 wt% H 2 with ideal adsorption energies of 0.163–0.228 eV. • High hardness and low electrophilicity provides the stabilities of H 2 adsorption. • Desorption temperature and thermodynamic analysis verify the reversibility of H 2 storage. [ABSTRACT FROM AUTHOR]

Graphene nanoflakes are widely utilized as high-performance molecular devices due to their chemical stability and light weight. In the present study, the interaction of aluminum species with graphene nanoflake (denoted as GR-Al) has been investigated using the density functional theory (DFT) method to elucidate the doping effects of Al metal on the electronic states of GR. The mechanisms of the diffusion of Al on GR surface and the hydrogen storage of GR-Al were also investigated in detail. The neutral, mono-, di-, and trivalent Al ions (expressed as Al, Al+, Al2+, and Al3+, respectively) were examined as the Al species. The DFT calculations showed that the charge transfer interaction between Al and GR plays an important role in the binding of Al species to GR. The diffusion path of Al on GR surface was determined: the barrier heights of Al diffusion were calculated to be 2.1–2.8 kcal mol−1, which are lower than Li+ on GR (7.2 kcal/mol). The possibility of using GR-Al for hydrogen storage was also discussed on the basis of the theoretical results.

In this study, a novel substrate complex is developed by integrating alkali metals such as Li/Na/K onto magnesium diboride (MgB 2). The research involves comprehensive density functional theory (DFT) to analyze the complex optimized structures, thermodynamic characteristics, and H 2 storage capabilities. The results underscore a subtle charge transfer from Li/Na/K to the pristine MgB 2 monolayer, augmenting its electropositive characteristics. This attribute proves particularly advantageous for H 2 storage, as it enhances the electrostatic interactions between the complex and hydrogen (H 2) molecules. The structure of Li/Na/K-decorated MgB 2 with various numbers of attached H 2 molecules is also explored. The maximum H 2 adsorption is observed with nine H 2 molecules for Li (n = 9H 2) and eight H 2 molecules for both Na and K (n = 8H 2). The adsorption energies for these configurations fall within the range of −0.24 to −0.21 eV for Li, −0.22 to −0.20 eV for Na, and −0.25 to −0.20 eV for K. Notably, gravimetric capacities of 14.6 wt%, 23.37 wt%, and 18.94 wt% are attained for Li, Na, and K-decorated MgB 2 , respectively. These values demonstrate a significant surpassing of the U–S Department of Energy (DOE) target of 5.5 wt%. This groundbreaking material has the potential to play a crucial role in promoting efficient and sustainable solutions for H 2 storage, meeting the increasing need for clean energy technologies. [Display omitted] • DFT study of alkali metal decorated magnesium diboride for hydrogen storage. • Adsorption energies in the range of −0.25 to −0.20 eV Li/Na/K-decorated MgB 2. • H 2 storage capacity of Li/Na/K decorated MgB 2 is 14.60, 23.37, and18.94 wt%. [ABSTRACT FROM AUTHOR]

While the challenge of storing hydrogen in inexpensive and renewable adsorbents is relentlessly pursued by researchers all over the world, application of hydrochar derived from biomass is also gaining attention as it can be subsequently chemically activated using activating agents like KOH in order to tailor the development of favorable porosity. However, the synergistic effect of hydrothermal carbonization (HTC) process conditions as well as KOH activating conditions on the development of surface morphology is required to be assessed with the application of such porous superactivated hydrochars in hydrogen storage application. In this study, highly porous superactivated hydrochars were fabricated from inexpensive and abundant loblolly pine. Loblolly pine was hydrothermally carbonized at 180 °C, 220 °C and 260 °C and the hydrochars were then activated at different experimental conditions of 700 °C, 800 °C and 900 °C using solid KOH to loblolly pine hydrochar ratio of 2:1, 3:1 and 4:1 to produce superactivated hydrochars. Superactivated hydrochars as well as loblolly pine and its corresponding hydrochars underwent physicochemical analysis as well as surface morphology analysis by SEM and nitrogen adsorption isotherms at 77 K in order to investigate the effect on BET, pore volume, and pore size distribution due to various process conditions. The superactivated hydrochars were then analyzed to quantify total hydrogen storage capacity of these materials at 77 K and up to pressure of 55 bar. Porosity of superactivated hydrochars were as high as 3666 m2/g of BET specific surface area (SSA), total pore volume of 1.56 cm3/g and micropore volume of 1.32 cm3/g with the hydrogen storage capacity of 10.2 wt% at 77 K and 55 bar. It was conclusive from principal component analysis that higher HTC temperature with moderate activation condition demonstrated favorability in developing porous superactivated hydrochars for hydrogen storage applications. • Synergistic effect of HTC temperature, KOH activation temperature, and ratio were analyzed for H 2 storage. • High HTC temperature and moderate KOH activating conditions maximized the surface morphology. • Maximum BET SSA and TPV were 3666 m2/g and 1.56 cm3/g, respectively, where H 2 storage was 10.2 wt% at 77 K and 55 bar. • PCA revealed that H 2 storage capacity was primarily correlated with BET SSA and total pore volume. [ABSTRACT FROM AUTHOR]

High level ab initio calculations were carried out to establish the half‐sandwich structural behavior of heavier group‐14 elements (SiPb) with neutral Be3 ring fragment and their molecular hydrogen adsorption capacity. The proposed complexes are found to be global minima on the potential energy surface after a rigorous systematic isomeric search. Quantum chemical investigation revealed that the complexes found possess high bond dissociation energy and also favorable thermodynamics of their formation. The complexes were also found to possess significant aromatic behavior. Among all the complexes, gravimetric density reaches more than the target level by US DOE in case of Be3Si and Be3Ge system which makes them potential target for molecular H2 storage. Furthermore, the average adsorption energy, Ead for these two complexes ranges between physisorption and chemisorption process, thereby suggesting their reversible H2 storage property. [ABSTRACT FROM AUTHOR]

Sodium alanate (NaAlH4) is a prospective H2 storage material for stationary and mobile applications, as NaAlH4 contains 7.4 wt% of H2, and it is possible to do multiple H2 release and accumulation cycles. Nanoconfinement is a potential solution to enhance the H2 release properties of NaAlH4. To optimize the supporting material and the synthesis method used for the nanoconfinement of NaAlH4, a better understanding of the influence of nanoconfinement on the H2 release processes is necessary. Thus, the H2 release from bulk, purely nanoconfined, and intermediate NaAlH4 is measured at different temperature ramp rates, and the characteristic parameters for each hydrogen release process are determined. Activation energies for each process are determined using the Kissinger method, and the effect of nanoconfinement on the activation energies is analysed. The impact of nanoconfinement on the H2 release processes from NaAlH4 and the limitations of each process in case of bulk and nanoconfined NaAlH4 are presented and discussed. Nanoconfinement of NaAlH4 decreases activation energies of the initial reversible H2 release steps to between 30 and 45 kJ mol−1 and increased the activation energy of the last irreversible H2 release step to over 210 kJ mol−1.

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. [Display omitted] • 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. [ABSTRACT FROM AUTHOR]

At present, LNG vessels without reliquefaction plants consume the BOG (boil-off gas) in their engines and the excess is burned in the gas combustion unit without recovering any of its energy content. Excess BOG energy could be captured to produce H2, a fuel with high energy density and zero emissions, through the installation of a reforming plant. Such H2 production would, in turn, require on-board storage for its subsequent consumption in the propulsion plant when navigating in areas with stringent anti-pollution regulations, thus reducing CO2 and SOX emissions. This paper presents a review of the different H2 storage systems and the methods of burning it in propulsion engines, to demonstrate the energetic viability thereof on board LNG vessels. Following the analysis, it is identified that a pressurised and cooled H2 storage system is the best suited to an LNG vessel due to its simplicity and the fact that it does not pose a safety hazard. There are a number of methods for consuming the H2 generated in the DF engines that comprise the propulsion plant, but the use of a mixture of 70% CH4-30% H2 is the most suitable as it does not require any modifications to the injection system. Installation of an on-board reforming plant and H2 storage system generates sufficient H2 to allow for almost 3 days’ autonomy with a mixture of 70%CH4-30%H2. This reduces the engine consumption of CH4 by 11.38%, thus demonstrating that the system is not only energy-efficient, but lends greater versatility to the vessel.

Molecular dynamics simulation has been performed for H2 gas adsorption for silver nanoparticle supported on different shapes of defect in carbon nanotube (CNT). Square, rectangle and line defects in CNT has been investigated for H2 gas adsorption for silver nanoparticle supported on CNT. Different Size of silver nanoparticle, aluminum doping in silver nanoparticle and different temperature has been investigated for H2 storage on silver nanoparticle supported in CNT with different defect shapes. Diffusion coefficient for silver nanoparticle supported on square defect shapes of CNT is more than diffusion coefficient of silver nanoparticle supported on other defect shapes of CNT. Irreversibility structure is observed in silver nanoparticle supported on all shapes defect of CNT and irreversibility structure for silver supported in line defect shapes of CNT is more strong than other defect shapes of CNT. There is none monotonic behavior for H2 adsorption as a function of Aluminum doping on surface of silver-aluminum bimetallic nanocluster on square and line defect shapes of CNT. In current case study, by engineering the size of Aluminum nanoparticle, it is possible to reach certain international standards goals for H2 storage which is set by the United States Department of Energy (DOE). • Non monotonic behavior of H2 adsorption in Al–Ag nanoalloy supported on line and square defect in CNT versus Al doping. • More H2 adsorption in Al–Ag bimetallic nanoparticle supported in line defect of CNT. • Non and strong changes on H2 arrangement on Al and Ag supported on CNT with defect respectively. [ABSTRACT FROM AUTHOR]

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 %. [ABSTRACT FROM AUTHOR]

Based on first−principles calculations, we investigate the possibility of the two-dimensional porous C 9 N 4 material as for hydrogen storage, and find that the adsorption energy of H 2 molecules on the pristine C 9 N 4 is too weak to meet the requirements of hydrogen storage, whereas the adsorption on the Li−decorated sheet is relatively moderate. Each C 9 N 4 unit cell can incorporate 6 Li atoms, of which 3 Li atoms are located above the intrinsic hole and the others are below. The unit cell can hold 14 hydrogen molecules with an average adsorption energy of −0.12 eV, which meets the reversible storage condition of hydrogen, and the gravity density reaches 7.04 wt%. Particularly, 6Li@C 9 N 4 maintains excellent H 2 storage performance under a tensile strain within 2%. The ab initio MD simulations performed at 300 K show that all 14 H 2 molecules remained on the double sides of 6Li@C 9 N 4 in the absence and presence of strain. Therefore, we predict that Li−modified C 9 N 4 could be a potential material with excellent ductility for hydrogen storage at room temperature. • The adsorption of H 2 on C 9 N 4 is too weak to ensure the reversible storage of H 2. • Decorated by 6 Li atoms, the hydrogen storage capacity of C 9 N 4 is significantly enhanced. • At room temperature, all H 2 are adsorbed stably on 6Li@C 9 N 4 , and the storage capacity remains. • Applied a tensile strain within 2% during the H 2 storage process, 6Li@C 9 N 4 exhibits good ductility. [ABSTRACT FROM AUTHOR]

Summary: Commercially available open‐cell polyurethane foams (OCPUF) have been successively functionalized with bio‐inspired polydopamine coating (OCPUF@PDA), and activated with cobalt nanoparticles (OCPUF@PDA@Co). The resulting soft structured catalytic support (S2CS) has been used as a highly efficient tool for the release of dihydrogen from a commercially available alkaline sodium borohydride solution at room temperature. With a diluted solution containing 0.4 wt% NaBH4 and 0.4 wt% NaOH, the hydrogen generation rate was of 76.4 ± 3.18 L·h−1·gcat−1 after stabilization of the catalytic activity. The catalytic tool could be used for 10 runs. [ABSTRACT FROM AUTHOR]

The goal of the review series on the H 2 economy is to highlight the current status, major issues, and opportunities associated with H 2 production, storage, transportation, distribution and usage in various energy sectors. In particular, Part I discussed the various H 2 (grey and green) production methods including the futuristic ones such as photoelectrochemical for small, medium, and large-scale applications. Part II of the H 2 economy review identifies the developments and challenges in the areas of H 2 storage, transportation and distribution with national and international initiatives in the field, all of which suggest a pathway for establishing greener H 2 society in the near future. Currently, various methods, comprising physical and chemical routes are being explored with a focus on improving the H 2 storage density, capacity, and reducing the cost. H 2 transportation methods by road, through pipelines, and via ocean are pursued actively in expanding the market for large scale applications around the world. As of now, compressed H 2 and its transportation by road is the most realistic option for the transportation sector. • H 2 storage in compressed form is the commercially viable technology at present. • Critical cost factors in H 2 storage, transportation and distribution are provided. • Logistic flow of H 2 from storage points to various mobility applications is presented. • H 2 transportation by road, pipeline and ocean is reviewed for large-scale application. • Compressed H 2 transportation by road is the viable option for the automotive sector. [ABSTRACT FROM AUTHOR]

At present, LNG vessels without reliquefaction plants consume the BOG (boil-off gas) in their engines and the excess is burned in the gas combustion unit without recovering any of its energy content. Excess BOG energy could be captured to produce H2, a fuel with high energy density and zero emissions, through the installation of a reforming plant. Such H2 production would, in turn, require on-board storage for its subsequent consumption in the propulsion plant when navigating in areas with stringent anti-pollution regulations, thus reducing CO2 and SOX emissions. This paper presents a review of the different H2 storage systems and the methods of burning it in propulsion engines, to demonstrate the energetic viability thereof on board LNG vessels. Following the analysis, it is identified that a pressurised and cooled H2 storage system is the best suited to an LNG vessel due to its simplicity and the fact that it does not pose a safety hazard. There are a number of methods for consuming the H2 generated in the DF engines that comprise the propulsion plant, but the use of a mixture of 70% CH4-30% H2 is the most suitable as it does not require any modifications to the injection system. Installation of an on-board reforming plant and H2 storage system generates sufficient H2 to allow for almost 3 days' autonomy with a mixture of 70%CH4-30%H2. This reduces the engine consumption of CH4 by 11.38%, thus demonstrating that the system is not only energy-efficient, but lends greater versatility to the vessel. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are crystalline porous materials that have been actively explored for various gas storage, separation, and conversion applications because of their structural tunability. While the micropores (<2 nm) in MOFs are essential for increased gas affinity, these small pores significantly decrease the mass-transport kinetics. One way to address this challenge is to develop hierarchically porous MOFs with interconnected micro-, meso-, and macropores. Whereas these MOFs can be formed by using soft/hard templates or by creating pores through postmodification, they can also be achieved by growing them on structural templates such as porous carbons, i.e., reduced graphene oxide. The latter strategy can enable the introduction of hierarchical porosity while creating a synergistic effect to simultaneously improve both the mechanical property and gas affinity by creating pores at the interface. In this direction, we demonstrated that the coating of HKUST-1 onto a hierarchically porous reduced graphene oxide (HRGO) led to the formation of a hierarchically porous structure, namely, HKUST-1@HRGO, with increased affinity toward H2 gas. While the isosteric heats of adsorption (Qst) values for H2 were found to be 7.7, 6.9, and 6.7 kJ mol–1 for HRGO, HKUST-1, and the physical mixture of HKUST-1 and HRGO, respectively, at zero coverage, that of the HKUST-1@HRGO composite revealed a significant increase of up to 9.26 kJ mol–1, thus clearly demonstrating not only the synergetic effect between HKUST-1 and the reduced graphene oxide but also the critical role of interfacial pores as high-affinity binding sites. [ABSTRACT FROM AUTHOR]

Bangladesh is a developing country heavily reliant on fossil fuels, which emits toxic gases during its combustion. In that scenario, hydrogen is an eco-friendly fuel source with a calorific value of 120 MJ/kg which is significantly higher than fossil fuels. With a density of 0.09 kg/m3 at 273 K, hydrogen is just 1/14th that of air. Considering the enriched agricultural resources of Bangladesh, biomass gasification emerges as the most advantageous method for hydrogen production. Compared to other methods like steam reforming and electrolysis, biomass gasification offers significant cost advantages. Furthermore, being an overpopulated country generates significant organic waste annually. The mismanagement of these wastes creates problematic situations for both lives and surroundings. This review approaches the way of waste management and hydrogen production and additionally discusses the current scenario, several hydrogen production pathways, utilization, and storage. This study focused on hydrogen production and utilization in Bangladesh, which will help the researchers to identify suitable and cost-effective methods to obtain the decarbonization goal in the energy sector. [Display omitted] • Global warming is increasing due to excessive use of fossil fuels. • H 2 has a higher calorific value compare to fossil fuels. • The government plans to generate 40 % of its power with clean energy by 2041. • Biomass gasification is suitable for producing H 2 in Bangladesh. [ABSTRACT FROM AUTHOR]

Conductive borophene nanostructures are proposed as an excellent candidate material for charge-controlled switchable H 2 storage. Based on density functional theory calculations, we investigate the H 2 adsorption on the charged borophene nanosheet. It is found that the adsorption energies of H 2 on either positively or negatively charged borophene nanosheets are dramatically enhanced in compared with the neutral material. Charge modulation strategies therefore offer the potential for spontaneous, controllable H 2 storage and release. Moreover, the positive or negative charging of borophene nanosheets can in principle achieve H 2 storage capacities of 6.5 wt%. These results could provide new insights in searching for materials with exceptionally high H 2 storage capacity. Image 1 • The positively or negatively charged borophene shows high H 2 adsorption capacity. • H 2 adsorption and desorption are simply modulated by injecting and removing extra charges. • The positively or negatively charged borophene could achieve H 2 storage capacities of 6.5 wt%. [ABSTRACT FROM AUTHOR]

Abstract Density Functional Theory (DFT) calculations were employed to study a series of coinage metal-hydrogen associations formulated as [M(Η 2) n ][A] (M = CuI, AgI or AuI, n = 1–5). The [M(Η 2) n ][A] salts utilize both their anions and cations for H 2 storage. The [M(Η 2) n ]+ cations could be stabilized in the solid state by voluminous counter-anions, i.e. the [(H 3 B) (BH 2 NH 2) 5 (NH 2)]-, [B(CNBH 3) 3 ]- and [B 12 H 12 ]- anions. The estimated bond dissociation energies (BDE s) of the M···(η 2-H 2) bonds are 5–17, 4–11 and 1–26 kcal/mol for the [Cu(Η 2) 4 ]+, [Ag (Η 2) 4 ]+ and [Au (Η 2) 4 ]+ cationic species respectively, while the fifth H 2 molecule is estimated to be very loosely associated to the metal center. Four H 2 molecules could be exploited from the [Cu(Η 2) n ][A] and [Ag (Η 2) n ][A] molecules in addition to the amount of H 2 stored in the anion [A]-. Among the [M(Η 2) n ][A] salts optimal gravimetric, kinetic and thermodynamic properties and relatively low cost, are predicted for [Cu(Η 2) n ][(H 3 B) (BH 2 NH 2) 5 (NH 2)]. Highlights • Solid stabilization of metal hydrides with optimal H 2 storage properties. • Weakly Coordinating Anions. • 'Complex hydrides', exploiting both anion and cation for H 2 storage. • Novel 'concept' design of 'complex hydrides'. [ABSTRACT FROM AUTHOR]

Abstract Molecular hydrogen storage on Ruthenium (Ru) decorated single-walled carbon nanotube (SWCNT) has been studied by using spin-polarized density functional theory (DFT). When a Ru atom is adsorbed on SWCNT, the Bader analysis reveals that Ru transfers a charge of 0.44e− to SWCNT. Accordingly, Ru acts as adsorption center for H 2 molecules; thus, it can hold up to four H 2 molecules with an adsorption energy (E ads) of −0.93 eV/H 2. A uniform addition of Ru atoms on SWCNT shows that this nanomaterial can adsorb up to five Ru without clustering. Each Ru atom of 5Ru-decorated SWCNT system can bind up to four H 2 molecules involving an E ads of −0.83 eV/H 2. After H 2 molecules adsorption, Ru atoms shifted from a near hollow site to a bridge site. Moreover, Ru-decorated systems reduce their magnetic moment when the number of H 2 molecules increase from 2 μ B to 0 μ B. Graphical abstract Image 1 Highlights • Doping Ru enhances H2 adsorption on a SWCNT more than 12 times. • Ru distribution at low concentration and Ru charge transfer to the SWCNT prevent Ru clustering. • Each five Ru atoms without clustering on a SWCNT can bind up to four H2 molecules. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydrogen release from a novel storage reactor with high capacities at low pressures. • Coupled magnesium hydride dehydrogenation and magnesium oxide hydration feasible. • Water vapor supply to the storage reactor at 10 bar and 350 °C possible. • Dehydrogenation rate dependent on the vapor supply-pressure. • Magnesium hydride dehydrogenation reaction fast enough for stationary applications. Abstract With hydrogen becoming more and more important as storage and carrier for renewable energy, there is an increasing need for flexible and efficient storage technologies. However, existing technologies, such as liquefaction or compression, often require a significant share of the hydrogens lower heating value. High-temperature metal hydrides (HT-MHs), such as magnesium hydride, are a promising alternative. Due to high operation temperatures, their application is challenging. A novel adiabatic hydrogen storage reactor based on the combination of a HT-MH with a thermochemical energy storage system (TCSS), such as Mg(OH) 2 /MgO + H 2 O, can be a solution. In this work, the previously published numerical simulations for hydrogen absorption are extended to the desorption process. A two-dimensional model for the hydrogen release was set up. The performance of the storage reactor is strongly dependent on the thermodynamic equilibrium of the reactions involved and less dependent on the reaction kinetics. Dehydrogenation is possible within 132 min, which is in the vicinity of the hydrogenation time. To enhance the dehydrogenation process, the water vapor pressure can be adjusted aiming for higher temperatures during the MgO hydration. Hydrogen can either be provided at constant pressure or constant mass flow rate. [ABSTRACT FROM AUTHOR]

The present research focuses on the synthesis and applications of a series of hyper-cross-linked polymer networks obtained from the one-step Friedel–Crafts reaction of triphenylsilane and formaldehyde dimethyl acetal. The materials were characterized through FTIR, 13C NMR, PXRD, TGA, N2 adsorption-desorption isotherms, H2 sorption and dye adsorption. These materials exhibited increased surface areas of approximately 441–1101 m2 g−1 with increasing ratio of monomer to cross-linker. The H2 storage capacity of the polymer networks reached 1.19 wt % (5.96 mmol g−1) under 1.03 bar and 77.3 K. In addition, the material showed excellent adsorption capacity of 806 mg g−1 for Congo Red and retained their adsorption capacity after recycling nine times. Taken together, the results demonstrate that the obtained hyper-cross-linked polymers could be applied to H2 storage and water treatment. [ABSTRACT FROM AUTHOR]

Today's scientific professionals face the challenge of meeting the ever-growing demand for hydrogen fuel. Hydrogen stands as a sustainable and eco-friendly alternative. This fuel is inherently lightweight and gaseous Which present challenges in its production, transportation, and storage. Hydrogen fuel can be stored using different storage methods which have merits and demerits. Hydrogen can be stored by conventional methods and also using the next generation materials, i.e., pressurized gas, liquid nitrogen at cryogenic temperature, chemical method storage in the metal hydride, and adsorption on carbon material. According to various researches, carbon material has been stated as a novel, emerging and next-generation material for storing hydrogen. Hierarchical carbon having modified 3-dimensional structure and multimodal pore can be prepared from different chemically or catalytically activation processes. The best-suited carbon material for hydrogen storage has a high specific surface area of 2000–3000 m2/g and also high interconnectivity of pore. In this review paper, the various hydrogen storage methods and performance of carbon materials for hydrogen storage at different pressure and temperature are reviewed. The utilization of carbon for hydrogen storage represents a prominent technology in addressing the obstacles linked with the use of hydrogen. [Display omitted] • Carbon based material production with properties best suited for hydrogen storage. • Next generation material and conventional method used for hydrogen storage. • Literature results on bio-derived carbon-based hydrogen storage are cited. [ABSTRACT FROM AUTHOR]