scholarly journals Hydrogen Adsorption in Carbon Materials

MRS Bulletin ◽  
1999 ◽  
Vol 24 (11) ◽  
pp. 45-50 ◽  
Author(s):  
M.S. Dresselhaus ◽  
K.A. Williams ◽  
P.C. Eklund
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Adsorption ◽  
Theoretical Calculations ◽  
Mass Density ◽  
Department Of Energy ◽  
Small Power ◽  
Adsorption Mechanisms ◽  
Graphite Nanofibers ◽  
Low Mass ◽  
Very High

Recent reports of very high, reversible adsorption of molecular hydrogen in pure nanotubes, alkali-doped graphite, and pure and alkali-doped graphite nanofibers (GNFs) have aroused tremendous interest in the research community, stimulating much experimental work and many theoretical calculations worldwide. The U.S. Department of Energy (DOE) Hydrogen Plan has seta standard for this discussion by providing a commercially significant benchmark for the amount of reversible hydrogen adsorption. This benchmark requires a system-weight efficiency (the ratio of stored H2 weight to system weight) of 6.5-wt% hydrogen and a volumetric density of 63 kg H2/m. If the encouraging experimental reports (summarized in Table I) are reproducible, it may be possible to reach the goals of the DOE Hydrogen Plan. On the other hand, the community still awaits confirmation of these experimental results by workers in other laboratories. Of additional concern is the fact that theoretical calculations have been unable to identify adsorption mechanisms compatible with the requirements of the DOE Hydrogen Plan.An economical, safe, hydrogen-storage medium is a critically needed component of a hydrogen-fueled transportation system. Hydrogen storage in a carbon-based material offers further advantages associated with its low mass density. Furthermore, fuel cell technology involving the conversion of hydrogen into protons, or hydrogen and oxygen into electric current, is being vigorously researched for both transportation and small power-plant applications.

Lithium Decorated Borane Clusters (BnHnLi6, n=5-7) as Promising Materials for Hydrogen Storage: A Computational Study

2021 ◽  
Author(s):  
Shakti S Ray ◽  
Sridhar Sahu
Keyword(s):  
Hydrogen Storage ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Md Simulations ◽  
Department Of Energy ◽  
Hydrogen Molecules ◽  
The Stability ◽  
Almost All

Abstract In this study, we have investigated the hydrogen adsorption potential of lithium decorated borane clusters (BnHnLi6, n = 5–7) using density functional theory calculations. The principle of maximum hardness and minimum electrophilicity confirmed the stability of the hydrogen adsorbed complexes. The outcomes of the study reveals that, the hydrogen molecules are adsorbed in a quasi-molecular fashion via Niu-Rao-Jena type of interaction with average adsorption energy falling in the range of 0.10-0.11eV/H2and average Li-H2 bond length is in the range of 2.436–2.550Å. It was found that the hydrogen molecules are physiosorbed at the host clusters at low temperature range 0K- 77K with gravimetric density up to 26.4 wt% which was well above target set by U.S. Department of Energy (US-DOE). ADMP-MD simulations showed that almost all the H2 molecules are desorbed at higher temperature form 373K-473K without distorting the host clusters which indicates the studied clusters can be promoted as promising reversible hydrogen storage

Discovering the Mechanism of H2 Adsorption on Aromatic Carbon Nanostructures to Develop Adsorbents for Vehicular Applications

2004 ◽  
Vol 837 ◽  
Author(s):  
A. C. Dillon ◽  
J. L. Blackburn ◽  
P. A. Parilla ◽  
Y. Zhao ◽  
Y-H. Kim ◽  
...  
Keyword(s):  
Binding Energy ◽  
Hydrogen Storage ◽  
Carbon Nanostructures ◽  
Hydrogen Adsorption ◽  
Iron Catalyst ◽  
The United States ◽  
Department Of Energy ◽  
United States Department ◽  
Iron Particles ◽  
Aromatic Carbon

ABSTRACTHydrogen adsorption has been observed with a binding energy of ∼ 50 kJ /mol on as-synthesized carbon multi-wall nanotubes (MWNTs). The MWNTs are virtually free of non-nanotube carbon impurities but contain residual iron catalyst particles. The MWNTs are also highly graphitic. No hydrogen adsorption is observed at near ambient temperatures for purified MWNTs that are free of iron particles. However, hydrogen adsorption is also not observed on bare iron particles even following reduction in the presence of hydrogen at 775 K. These results imply that a special synergy occurs when small iron particles or atoms are in intimate contact with sp2-hybridized aromatic carbon. Interestingly, reducing the as-synthesized MWNTs in H2 at 573 K results in an increased hydrogen capacity. Understanding this hydrogen storage mechanism could facilitate the economical engineering of a hydrogen storage material that meets the United States Department of Energy targets for vehicular fuel cell applications. Recent theoretical studies have shown that an iron ad atom forms a complex with a C36 fullerene and shares charge with four carbon atoms of a bent five-membered ring. Three H2 ligands then coordinate with the iron forming a stable 18-electron organometallic complex. Here the binding energy of the molecular hydrogen ligands is ∼43 kJ /mol. These theoretical results could possibly explain the unique hydrogen storage properties of MWNTs that are grown with an iron catalyst.

FIRST-PRINCIPLES STUDY OF Ti-CATALYZED HYDROGEN ADSORPTION ON LiB (001) SURFACE

2013 ◽  
Vol 12 (07) ◽  
pp. 1350065 ◽  
Author(s):  
WEIBIN ZHANG ◽  
AILING WU ◽  
YIDING LIU ◽  
SHAOLIN ZHANG ◽  
JIANHONG GONG ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
First Principles ◽  
Electronic Structures ◽  
Hydrogen Adsorption ◽  
Department Of Energy ◽  
Hydrogen Storage Material ◽  
Ambient Conditions ◽  
Storage Material ◽  
Practical Applications ◽  
Temperature And Pressure

Ti -doped LiB (001) is a promising material for hydrogen storage. The adsorption of H 2 is greatly enhanced by doping Ti into LiB (001), change the electronic structures of the surface Li , B atoms. After H 2 is adsorbed on the surface, the E ad of the ( H 2)n@ Ti / LiB (001) system is considered. It is around -0.22 eV/ H 2 to -0.31 eV/ H 2, which is close to the target specified by U.S. Department of Energy. The nature of the bonding between Ti and H 2 is due to the H 1s, Ti 4s and B 2s orbital hybridization. In addition, Ti 3d orbital is hybridized strongly with B -2p orbital, resulting in more stable Ti / LiB (001) system. These results are verified by the electron density distribution intuitively. It is found that the system can adsorb up to four H 2 at ambient temperature and pressure. Therefore, the Ti -doped LiB (001) would be a promising hydrogen storage material. Such optimal molecular hydrogen adsorption system makes H 2 adsorption feasible at ambient conditions, which is critical for practical applications.

scholarly journals Adsorption-Based Hydrogen Storage in Activated Carbons and Model Carbon Structures

Reactions ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 209-226
Author(s):  
Anatoly Fomkin ◽  
Anatoly Pribylov ◽  
Ilya Men’shchikov ◽  
Andrey Shkolin ◽  
Oleg Aksyutin ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Adsorption ◽  
Activated Carbons ◽  
Carbon Adsorbent ◽  
Department Of Energy ◽  
Polymer Mixture ◽  
Adsorbed Hydrogen ◽  
Hydrogen Density ◽  
Carbon Structures ◽  
Temperature And Pressure

The experimental data on hydrogen adsorption on five nanoporous activated carbons (ACs) of various origins measured over the temperature range of 303–363 K and pressures up to 20 MPa were compared with the predictions of hydrogen density in the slit-like pores of model carbon structures calculated by the Dubinin theory of volume filling of micropores. The highest amount of adsorbed hydrogen was found for the AC sample (ACS) prepared from a polymer mixture by KOH thermochemical activation, characterized by a biporous structure: 11.0 mmol/g at 16 MPa and 303 K. The greatest volumetric capacity over the entire range of temperature and pressure was demonstrated by the densest carbon adsorbent prepared from silicon carbide. The calculations of hydrogen density in the slit-like model pores revealed that the optimal hydrogen storage depended on the pore size, temperature, and pressure. The hydrogen adsorption capacity of the model structures exceeded the US Department of Energy (DOE) target value of 6.5 wt.% starting from 200 K and 20 MPa, whereas the most efficient carbon adsorbent ACS could achieve 7.5 wt.% only at extremely low temperatures. The initial differential molar isosteric heats of hydrogen adsorption in the studied activated carbons were in the range of 2.8–14 kJ/mol and varied during adsorption in a manner specific for each adsorbent.

scholarly journals Chemical modification of the polymer of intrinsic microporosity PIM-1 for enhanced hydrogen storage

Adsorption ◽  
2020 ◽  
Vol 26 (7) ◽  
pp. 1083-1091
Author(s):  
Mi Tian ◽  
Sébastien Rochat ◽  
Hamish Fawcett ◽  
Andrew D. Burrows ◽  
Christopher R. Bowen ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Surface Area ◽  
Hydrogen Adsorption ◽  
Sorption Properties ◽  
Bet Surface Area ◽  
Polymer Modification ◽  
Gas Sorption ◽  
Chemically Modified ◽  
Polymer Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

Abstract A detailed investigation has been carried out of the pre-polymerisation modification of the polymer of intrinsic microporosity PIM-1 by the addition of two methyl (Me) groups to its spirobisindane unit to create a new chemically modified PIM-1 analogue, termed MePIM. Our work explores the effects of this modification on the porosity of PIM-1 and hence on its gas sorption properties. MePIM was successfully synthesised using either low (338 K) or high (423 K) temperature syntheses. It was observed that introduction of methyl groups to the spirobisindane part of PIM-1 generates additional microporous spaces, which significantly increases both surface area and hydrogen storage capacity. The BET surface area (N2 at 77 K) was increased by ~ 12.5%, resulting in a ~ 25% increase of hydrogen adsorption after modification. MePIM also maintains the advantages of good processability and thermal stability. This work provides new insights on a facile polymer modification that enables enhanced gas sorption properties.

scholarly journals Visible AO Observations at Halpha for Accreting Young Planets

2013 ◽  
Vol 8 (S299) ◽  
pp. 32-33
Author(s):  
L.M. Close ◽  
K. Follette ◽  
J.R. Males ◽  
K. Morzinski ◽  
T.J. Rodigas ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Binary Stars ◽  
Optical Resolution ◽  
Ccd Camera ◽  
Short Exposure ◽  
Low Mass ◽  
Orion Trapezium ◽  
First Time ◽  
Adaptive Optics System ◽  
Very High

AbstractWe utilized the new high-order (250-378 mode) Magellan Adaptive Optics system (MagAO) to obtain very high-resolution science in the visible with MagAO's VisAO CCD camera. In the good-median seeing conditions of Magellan (0.5–0.7″) we find MagAO delivers individual short exposure images as good as 19 mas optical resolution. Due to telescope vibrations, long exposure (60s) r' (0.63μm) images are slightly coarser at FWHM = 23-29 mas (Strehl ~ 28%) with bright (R < 9 mag) guide stars. These are the highest resolution filled-aperture images published to date. Images of the young (~ 1 Myr) Orion Trapezium θ1 Ori A, B, and C cluster members were obtained with VisAO. In particular, the 32 mas binary θ1 Ori C1C2 was easily resolved in non-interferometric images for the first time. Relative positions of the bright trapezium binary stars were measured with ~ 0.6–5 mas accuracy. In the second commissioning run we were able to correct 378 modes and achieved good contrasts (Strehl>20% on young transition disks at Hα). We discuss the contrasts achieved at Hα and the possibility of detecting low mass (~ 1–5 Mjup) planets (past 5AU) with our new SAPPHIRES survey with MagAO at Hα.

Pressure Isotherms of Hydrogen Adsorption in Carbon Nanostructures

2001 ◽  
Vol 706 ◽  
Author(s):  
Xiaohong Chen ◽  
Urszula Dettlaff-Weglikowska ◽  
Miroslav Haluska ◽  
Martin Hulman ◽  
Siegmar Roth ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Activated Carbon ◽  
Hydrogen Storage ◽  
Carbon Nanostructures ◽  
Room Temperature ◽  
Storage Capacity ◽  
Hydrogen Adsorption ◽  
Single Wall Carbon Nanotubes ◽  
Hydrogen Storage Capacity ◽  
Carbon And Graphite

AbstractThe hydrogen adsorption capacity of various carbon nanostructures including single-wall carbon nanotubes, graphitic nanofibers, activated carbon, and graphite has been measured as a function of pressure and temperature. Our results show that at room temperature and a pressure of 80 bar the hydrogen storage capacity is less than 1 wt.% for all samples. Upon cooling, the capacity of hydrogen adsorption increases with decreasing temperature and the highest value was observed to be 2.9 wt. % at 50 bar and 77 K. The correlation between hydrogen storage capacity and specific surface area is discussed.

scholarly journals Mechanical bending effects on hydrogen storage of Ni decorated (8, 0) boron nitride nanotube : DFT study

2019 ◽  
Vol 16 (1) ◽  
pp. 299-325
Author(s):  
Atef Elmahdy ◽  
Hayam Taha ◽  
Mohamed Kamel ◽  
Menna Tarek
Keyword(s):  
Boron Nitride ◽  
Hydrogen Storage ◽  
Density Functional ◽  
Boron Nitride Nanotubes ◽  
Department Of Energy ◽  
Functional Theory ◽  
Activation Barriers ◽  
The Us ◽  
Adsorption Energies ◽  
Mechanical Bending

The influence of mechanical bending to tuning the hydrogen storage of Ni-functionalized of zigzag type of boron nitride nanotubes (BNNTs) has been investigated using density functional theory (DFT) with reference to the ultimate targets of the US Department of Energy (DOE). Single Ni atoms prefer to bind strongly at the axial bridge site of BN nanotube, and each Ni atom bound on BNNT may adsorb up to five, H2 molecules, with average adsorption energies per hydrogen molecule of )-1.622,-0.527 eV( for the undeformed B40N40-? = 0 , ) -1.62 , 0-0.308 eV( for the deformed B40N40-? = 15, ) -1.589,  -0.310 eV( for the deformed B40N40-? = 30, and ) -1.368-  -0.323 eV( for the deformed B40N40-? = 45 nanotubes respectively. with the H-H bonds between H2 molecules significantly elongated. The curvature attributed to the bending angle has effect on average adsorption energies per H2 molecule. With no metal clustering, the system gravimetric capacities are expected to be as large as 5.691 wt % for 5H2 Ni B40N40-? = 0, 15, 30, 45. While the desorption activation barriers of the complexes nH2 + Ni B40N40-? = 0 (n = 1-4) are outside the (DOE) domain (-0.2 to -0.6 eV), the complexes nH2 + Ni- B40N40-? = 0 (n = 5) is inside this domain. For nH2 + Ni- B40N40-? = 15, 30, 45 with (n = 1-2) are outside the (DOE) domain, the complexes nH2 + Ni- B40N40-? = 15, 30, 45 with (n = 3-5) are inside this domain. The hydrogen storage of the irreversible 4H2+ Ni- B40N40-? = 0, 2H2+ Ni- B40N40-? = 15, 30, 45 and reversible 5H2+ Ni- B40N40-? = 0, 3H2+ Ni- B40N40-? = 15, 30, 45 interactions are characterized in terms of density of states, pairwise and non-pairwise additivity, infrared, Raman, electrophilicity and molecular electrostatic potentials. Our calculations expect that 5H2- Ni- B40N40-j = 0, 15, 30, 45 complexes are promising hydrogen storage candidates.

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