Hydrogen Storage Capacity Of Ti Research Articles

Stable and 7.7 wt% hydrogen storage capacity of Ti decorated Irida-Graphene from first-principles calculations

Solid-state hydrogen storage is crucial for the widespread applications of hydrogen energy. It is a grand challenge to find appropriate materials that provide high hydrogen density and ambient temperature stability. Herein, we investigated the potential of Ti-decorated Irida-Graphene, a promising effective hydrogen storage system, as a novel hydrogen storage material using first-principles calculation. Irida-Graphene is a two-dimensional isomer of carbon consisting of tri-, hexa-, and octagon rings of carbon. Ti atoms are tightly bounded to the hexagonal rings. Binding energy analysis reveals that a single Ti atom in the primitive unit-cell of Ti-decorated Irida-Graphene is capable to bind up with 5H2 molecules and the average adsorption energy was −0.41 eV/H2. It indicates the gravimetric density of 7.7 wt%. The stability is attributed to Kubas-type interactions and ensured by a 5.0 eV diffusion energy barrier that prevents the Ti–Ti clustering. Further, ab initio molecular dynamics simulations results illustrate that the system remains stable at 600 K, higher than the desorption temperature of 524 K, implying the stability of the system during hydrogen recharge and discharge. The exceptional hydrogen storage performance suggests that Ti-decorated Irida-Graphene is an outstanding candidate for hydrogen storage materials.

Improved hydrogen storage properties of Ti2CrV alloy by Mo substitutional doping

Controllable hydrogen release is of great importance to the practical application of hydrogen storage materials. Ti 2 CrV alloy possesses the maximum hydrogen absorption capacity in the Ti–Cr–V series alloys, however, can hardly meet the reversible storage capacity of practical applications due to its stable dihydride. Here we report an advancement in hydrogen storage property of the Ti 2 CrV alloy by Mo partial substitution for Ti. Although the hydrogen absorption kinetics slightly decreased with the increase of Mo content, the Mo substitution alloy achieves an effective hydrogen capacity of 2.23 wt% cutting-off at 0.1 MPa, much higher than Ti 2 CrV alloy (0.8 wt%). It is ascribed that Mo partial substitution for Ti significantly decreased the dihydride stability as well as the enthalpy change value. The cyclic property of Ti 2 CrV alloy drastically decreased, while Mo substitution alloy with smaller FWHM value can maintain 90% storage capacity after 20 cycles. Because lattice strain and distortion of the Ti 2 CrV alloy were decreased by Mo doping. • Mo doping significantly enhanced the effective hydrogen storage capacity of Ti 2 CrV alloy. • Mo doping decreased lattice parameters, FWHM values, and enthalpy change of Ti 2 CrV alloy. • Mo substitution improved the cyclic property of the alloy. • Kinetics and thermodynamics of Mo-doped alloy upon de-/hydrogenation were calculated.

Study of hydrogen storage capacity of Ti induced by ion irradiation

A study of the change in hydrogen absorption of titanium due to ion irradiation is presented. Titanium slices were irradiated at room temperature with 700 and 1500 keV H ions and annealed at 300, 450 and 600 °C in a hydrogen atmosphere in order to study the absorption of hydrogen into the material. ERDA measurements and X-ray diffraction analysis show an improvement in hydrogen absorption relative to those samples that were not irradiated previously to hydrogenation. A tendency of an increment of the surface hydrogen storage density with diminishing the irradiation energy was also observed.

The effect of Sc addition on the hydrogen storage capacity of Ti0.32Cr0.43V0.25 alloy

The effect of the addition of 4th element on the hydrogen storage capacity of Ti 0.32 Cr 0.43 V 0.25 alloy was evaluated by simulation and confirmed experimentally. The crystal lattice volume, phase formation energy, and hydrogen absorption energy of the alloys were calculated by ab initio calculation for the alloys containing the third-period transition metals as Sc, Cr, Mn, Fe, Co, Ni, Cu, and Zn. It was postulated that the hydrogen absorption would be favored by large crystal volume and low hydrogen absorption energy. The calculation suggested Sc as the most suitable element and the hydrogen capacities of a series of Ti 0.32 Cr 0.43− x V 0.25 Sc x alloys ( x = 0.02–0.1) were determined accordingly. Among the alloys, the capacities of Ti 0.32 Cr 0.41 V 0.25 Sc 0.02 and Ti 0.32 Cr 0.39 V 0.25 Sc 0.04 alloys were higher than that of the Ti 0.32 Cr 0.43 V 0.25 alloy. The capacity of both alloys could be enhanced further by the heat treatment at 1250 °C due to the elimination of the second-phase TiCr 2 . • The ab initio calculation suggested Sc as the most suitable element in Ti–M–V alloys. • Ti–Sc–V alloy shows the lowest hydrogen absorption energy among Ti–M–V alloys. • The absorbed amount of hydrogen in Ti–Cr–V could be increased by addition of Sc. • The capacity could be enhanced by heat treatment due to elimination of TiCr 2 .

First-principles study of hydrogen storage on Ti-decorated B2C sheet

The hydrogen storage capacity of Ti decorated B2C sheet has been investigated by first-principles plane-wave calculation. It is revealed that a single Ti atom adsorbed on the B2C sheet can strongly bind up to four hydrogen molecules. The adsorption energy is in the range of −0.36–−0.82eV/H2, which is suitable for ambient temperature hydrogen storage. Considering the fact that Ti can be loaded on both sides of B2C sheet, corresponding gravimetric storage capacity of Ti/B2C system was also calculated and it can reach to about 7.0wt%, exceeding the minimum requirement of 6.0wt% for applications.

Hydrogen storage in Li and Ti decorated borazine: A first-principles study

The capacity of hydrogen storage in alkali metal (Li, Na, or K), alkaline-earth metal (Be, Mg, or Ca), or Ti decorated borazine has been investigated by using the first-principles calculations based on density functional theory. Our results indicated that alkali metals could bind strongly to the inorganic molecule borazine and, especially, Li decorated borazine exhibits the highest hydrogen storage capacity up to 10.4 wt % theoretically. The adsorption energies of hydrogen molecules are in the range of −0.10∼−0.15 eV/H2 (−0.23∼−0.28 eV/H2 for local density approximation calculation) which are acceptable for reversible H2 adsorption/desorption near ambient temperature. We also found that the hydrogen storage capacity of Ti decorated borazine is about 7.2 wt %, less than that of the Li decorated system, but the adsorption energies are in the range of −0.16∼−0.24 eV/H2 due to the Kubas interaction, which is larger than that of the Li decorated borazine and the system is also suitable for reversible H2 adsorption/desorption near ambient temperature.

Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage

In a recent letter [T. Yildirim and S. Ciraci, Phys. Rev. Lett. 94, 175501 (2005)], the unusual hydrogen storage capacity of Ti decorated carbon nanotubes has been revealed. The present paper extends this study further to investigate the hydrogen uptake by light transition-metal atoms decorating various carbon-based nanostructures in different types of geometry and dimensionality, such as carbon linear chain, graphene, and nanotubes. Using first-principles plane-wave method we show that not only outer but also inner surface of a large carbon nanotube can be utilized to bind more transition-metal atoms and hence to increase the storage capacity. We also found that scandium and vanadium atoms adsorbed on a carbon nanotube can bind up to five hydrogen molecules. Similarly, light transition-metal atoms can be adsorbed on both sides of graphene and each adsorbate can hold up to four hydrogen molecules yielding again a high-storage capacity. Interestingly, our results suggest that graphene can be considered as a potential high-capacity ${\mathrm{H}}_{2}$ storage medium. We also performed transition state analysis on the possible dimerization of Ti atoms adsorbed on the graphene and single-wall carbon nanotube.

Enhancement of hydrogen storage capacity of Ti–V–Cr–Mn BCC phase alloys

The phase structures and hydrogen absorption–desorption properties of Ti–V–Cr–Mn alloys were investigated. It is found that the increasing V content is effective for enhancing the hydrogen absorption capacity and flattening the hydrogen desorption plateau, while it depresses the hydrogen desorption plateau pressure. With the increase of V content, two phases of BCC and C14 Laves of the alloys transform into a single BCC phase. The maximum and effective hydrogen storage capacities among studied alloys are 3.98 and 2.51 wt.%, respectively, which open the hope to bring Ti–V-based alloy into the reach of practical application for onboard hydrogen storage systems in fuel cell powered vehicles.

The structure and electrochemical properties of ball-milled Ti 0.9Zr 0.2Mn 1.6Ni 0.2V 0.2 alloys

The high-energy ball-milling technique is generally used to modify the surface structure and texture of materials in order to improve their physical or chemical properties. In the conditions of thermodynamic equilibrium, the hydrogen-storage capacity of Ti 0.9Zr 0.2Mn 1.6Ni 0.2V 0.2 alloy can reach 240.9 ml/g, from which it can be calculated that its theoretical capacity is 537.3 mA h/g. However, its discharge capacity in KOH solution is only less than 40 mA h/g. In order to improve this capacity, the effect of ball milling with Ni powders on the electrochemical and structural properties of Ti 0.9Zr 0.2Mn 1.6Ni 0.2V 0.2 alloy was investigated. The results show that proper ball milling with Ni powders is very effective to improve the discharge capacity of the Ti 0.9Zr 0.2Mn 1.6Ni 0.2V 0.2 alloy by increasing the surface electrocatalytic ability.

Improved Hydrogen Storage Capacity of Ti<SUB>60</SUB>Zr<SUB>15</SUB>Ni<SUB>15</SUB>Cu<SUB>10</SUB> Amorphous Alloy

The hydrogen absorption property of a Ti 60 Zr 15 Ni 15 Cu 10 amorphous alloy is presented. The maximum hydrogen concentration of the amorphous alloy was 1.41 H/M at room temperature. The hydrogen absorption at lower temperatures with higher H 2 pressures favored higher H/M ratios for the amorphous alloy without any crystalline hydride growth. The structures of the as-quenched and hydrogenated samples were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The absorption was accompanied by expansion of interatomic spacing in the amorphous structure. The hydrogen storage ability of the Ti 60 Zr 15 Ni 15 Cu 10 amorphous alloy was found to be better than that of the related crystalline phase in this system.

Hydrogen storage properties of Ti 1 + xCr 2− yMn y alloys

Fundamental studies were performed with the aim of developing hydrides of titanium-based alloys with suitable properties for hydrogen and energy storage applications. We investigated the hydrogen absorption-desorption characteristics of the alloy Ti 1 + x Cr 2− y Mn y (0.1 ⩽ x ⩽ 0.3; 0 ⩽ y ⩽ 1). The rate of the initial activation process increased as x was increased, but the reversible hydrogen storage capacity decreased. Ti 1 + x Cr 2− y Mn y reacted readily with hydrogen to form hydrides at a hydrogen pressure of 40 atm and −20 °C. The reversible hydrogen storage capacity of Ti 1.2Cr 2−yMn y decreased with decreasing manganese content while the plateau pressure increased. The hysteresis in the absorption-desorption isotherms decreased markedly for titanium concentrations in the range 0.2 ⩽ x ⩽ 0.3 and for manganese concentrations in the range 0.5 ⩽ y ⩽ 0.8.