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We have investigated the electronic properties, adsorptions strength and charge transfer using first principles calculations using density functional theory (DFT). The hexagonal boron nitride (h-BN) substrate shows metallic behavior, which helps to enhance the absorption process. The adsorption of three different orientations (S, D and T) of the H2S gas molecules to analyze the maximum adsorption strength from them onto a copper cluster (Cu4) based on h-BN nanosheet. The maximum adsorption energy of the H2S gas molecule is -1.50 eV for the S orientation and for D and U, it is -0.71 eV and -0.78 eV, respectively. The results show that Cu4 cluster helps to capture H2S gas from the environment and results are useful for the cleaning environment from the toxic gases. [ABSTRACT FROM AUTHOR]

The influence of hydrogenation parameters on the hydrogen sorption rate by commercially pure titanium alloy coated by nickel layer was investigated. Sievert apparatus was used for investigation of hydrogen interaction with commercially pure titanium alloy. It was shown that increasing the coating deposition time from 10 to 50 minutes reduces the hydrogen sorption rate more than 7 times. With increasing temperature from 350 °C to 550 °C the hydrogen sorption rate increases more than 20 times in the pressure range of 1-2 atm. Increasing the hydrogen pressure in the chamber from 1 to 2 atm. accelerates the hydrogenation process by several times. The activation energy of hydrogen adsorption increases with hydrogenation pressure. [ABSTRACT FROM AUTHOR]

This work is focused on the investigation of hydrogen sorption behavior by zirconium alloy Zr1Nb with different surface states. Zirconium alloy samples in initial state, after ion cleaning with subsequent nickel deposition and after treatment by Low Energy High Current Pulsed Electron Beam (LEHCPEB) were hydrogenated at constant pressure and different temperatures. Hydrogen sorption rates as well as the energy of hydrogen adsorption by zirconium alloy with different surface states have been evaluated. It was shown, that ion cleaning with subsequent nickel deposition leads to the hydrogen sorption rate increasing at temperatures 350 - 550 °C, while the energy of hydrogen adsorption by zirconium alloy reduces on 15%. Modification by LEHCPEB leads to the hydrogen sorption rate decreasing at temperatures 350 - 550 °C, while the energy of hydrogen adsorption by zirconium alloy grows on 15%. [ABSTRACT FROM AUTHOR]

One storage concept for hydrogen-fueled vehicles is physical adsorption of hydrogen at cryogenic temperatures (nominally 80 K). During long idle periods, parasitic heat transfer from the environment induces desorption to the tank void volume. This desorption increases tank pressure such that it must be vented. To reduce the amount of fuel lost to venting, parasitic heating is minimized using multi-layer vacuum insulation and thermally isolating structures. A model is developed to predict the amount of conduction through structural supports and hydrogen lines, radiation through multi-layer insulation, and rarified gas conduction in the vacuum jacket of a tank sized for adsorption storage. The model reveals that conduction through structural supports is significant for cases of interest. Thus, two structural support architectures are compared: one utilizing G-10 CR composite and another involving KevlarTM cable. The structural members are sized to support comparable inertial loadings; the overall parasitic heat transfer is found to be as much as 38 percent less for the KevlarTM design. A lumped-parameter tank simulation is used to relate parasitic heat transfer to dormancy time and venting rate. The results of thermal testing of a sub-scale tank simulator are compared with model predictions. [ABSTRACT FROM AUTHOR]

In our effort to do first principles design of suitable materials for hydrogen storage, we have explored the interaction characteristics of a hydrogen molecule with pure as well as a 3d-transition metal (TM) atom doped Mg(0001) surface using density functional theory (DFT) based approach. Doping of a 3d-TM atom by creating a vacancy on the top most layer of Mg(0001) surface, enhances the molecular hydrogen adsorption efficiency of this surface by ~ 6 times. The TM atom gains some charge from the defected site of the Mg(0001) surface, becomes anionic and adsorbs the hydrogen molecule via Anti Kubas-type interaction. The interaction energy of this H2 molecule, including van der Waals dispersion correction, turns out to be ~ 0.4 eV, which falls in the right energy window between physisorption and chemisorption. On full coverage of this 3d-TM atom doped Mg(0001) surface with hydrogen molecules, the gravimetric density of hydrogen has been estimated to be ~ 5.6 wt %, thereby satisfying the criteria set by the department of energy (DOE) for efficient hydrogen storage. [ABSTRACT FROM AUTHOR]

Porous graphene (PG) has been decorated with Li atoms and subsequently studied the hydrogen (H2) adsorption characteristics, by using Density Functional Theory (DFT)-based calculations. A 2x2 PG has been decorated with eight Li atoms. Upto four H2 molecules get adsorbed on each Li atom. The maximum H2 storage capacity that could be achieved in 2x2PG-8Li is 8.95 wt% which is higher than the U.S. DOE's revised target for the on-board vehicles. The average H2 adsorption binding energy is 0.535 eV/H2, which lies between 0.2-0.6 eV/H2 that is required for achieving adsorption and desorption at near ambient conditions. Thus, Li-decorated PG could be a viable option for on-board automobile applications. [ABSTRACT FROM AUTHOR]

In the present study, the hydrogen storage performance of SPEEK-h-BN nanocomposite membrane is investigated. The SPEEK-h-BN nanocomposite is prepared by using phase inversion technique. Hydrogen adsorption studies have been carried out for the membranes using a Seiverts-like hydrogenation setup. The synthesized membranes are characterized by ¹H NMR, Raman spectroscopy, SEM, EDS, CHN-elemental analysis and TGA to analyze the membrane at various steps of experiments. It is observed that the SPEEK-h-BN nanocomposite membrane shows the enhanced performance compared to the pure SPEEK with a maximum storage capacity of 2.98 wt. % at 150 °C and the adsorbed hydrogen possess the average binding energy of 0.38 eV, while the pure SPEEK shows the storage capacity of 0.66 wt. % at 150 °C and the average binding energy of hydrogen of 0.36 eV. The TGA study shows the dehydrogenation of hydrogenated SPEEK-h-BN nanocomposite favors in the temperature range of 214 -218 ℃. [ABSTRACT FROM AUTHOR]

The cubic phase alloys Ti2Nb1-xFex (x = 0.0, 0.4, 0.6) have been prepared by an arc melting method. The crystal structure and hyperfine interactions have been carried out using X-ray diffraction and Mo¨ssbauer spectroscopy, respectively. Room temperature 57Fe Mo¨ssbauer spectra could be fitted with one doublet and four doublets for the alloys and their hydrides, respectively. The hydrogen absorption capacity increases with increase in Fe substitution. [ABSTRACT FROM AUTHOR]

In this work, hydrogen storage in (10,10) armchair single walled carbon nanotube (SWCNT) functionalized with magnesium hydride (MgH2) has been investigated. As expected, due to light weight of MgH2, the system (SWCNT-MgH2) exhibits a storage capacity of 6.44 wt.%. The hydrogen adsorptions are molecular. The system is stable and thus H2 molecules can be desorbed without affecting the C - Mg attachment. Dimerization of MgH2 molecules has been observed. The binding energies confirm that the system can be used as a practical hydrogen storage medium. [ABSTRACT FROM AUTHOR]

The cubic phase alloys Ti2Nb1-xFex (x = 0.0, 0.4, 0.6) have been prepared by an arc melting method. The crystal structure and hyperfine interactions have been carried out using X-ray diffraction and Mo¨ssbauer spectroscopy, respectively. Room temperature 57Fe Mo¨ssbauer spectra could be fitted with one doublet and four doublets for the alloys and their hydrides, respectively. The hydrogen absorption capacity increases with increase in Fe substitution. [ABSTRACT FROM AUTHOR]

In this work, hydrogen storage in (10,10) armchair single walled carbon nanotube (SWCNT) functionalized with magnesium hydride (MgH2) has been investigated. As expected, due to light weight of MgH2, the system (SWCNT-MgH2) exhibits a storage capacity of 6.44 wt.%. The hydrogen adsorptions are molecular. The system is stable and thus H2 molecules can be desorbed without affecting the C - Mg attachment. Dimerization of MgH2 molecules has been observed. The binding energies confirm that the system can be used as a practical hydrogen storage medium. [ABSTRACT FROM AUTHOR]

From the first-principle study, it is shown that the introduction of strain in a monolayer graphene enhances its chemical reactivity and hence it becomes more reactive than the pristine one. The intermolecular interaction between graphene and molecular hydrogen increases with increase in strain in the graphene plane leading to adsorption of hydrogen with suitable binding energy. Since graphene sheets can be freely suspended without any substrate we can stretch the sheets by adjusting distance between the clamped edges of the holding frame. In this way stacks of stretched graphene sheets can be constructed and a good hydrogen storage system can be obtained. [ABSTRACT FROM AUTHOR]

The adsorption and desorption of hydrogen in SWCNTs functionalized with borane is investigated experimentally. The SWCNTs are functionalized with borane (BH3) using LiBH4 as the precursor. The functionalized samples are hydrogenated and storage capacities of 3.2 wt.% and 3.8 wt.% are achieved at 50°C. Desorption of hydrogen is carried out by thermal annealing. Experimental evidences are provided by FTIR, CHNS and TG/TDS techniques. From the results it is confirmed that the designed hydrogen storage system is suitable for vehicular fuel cells. [ABSTRACT FROM AUTHOR]

Graphite nanoplatelets (GNP) were prepared by thermal exfoliation of acid intercalated graphite and functionalized by acid treatment.. The high pressure hydrogen adsorption-desorption measurements were carried out for f-GNP. The exfoliated f-GNP shows a hydrogen storage capacity of 0.5 wt % at 20 bar and 300 K. [ABSTRACT FROM AUTHOR]