Single crystal Ytrria-stabilized Zirconia was irradiated with Xe2+ and Xe3+ ions at 320 and 450 keV over a range of doses from 1013 to 1016 ions/cm2. Damage appears as a 150 nm surface layer with a dense dislocation network. The X-ray diffraction pattern shows an increasing lattice expansion with increasing dose that reaches a saturation point. Ion irradiation increases the surface conductance of the material; this effect is removed with certain post-treatments. Preliminary isotope depth profiling indicates enhanced ion diffusion in the damaged layer.

Sensor response characteristics of Ru/3C-SiC (epitaxial layer of SiC on Si substrates) Schottky junctions were studied at different temperatures (200 – 400 °C) in presence of varying concentrations of hydrogen from 5000 – 20000 ppm. The output signal of the sensor, the response time and the reversibility were investigated from the transient response characteristics of the sensors. The sensor parameters improved with higher operating temperature, up to 400 °C. The sensitivity of the sensors was found to be a function of applied bias across the Schottky junction. As compared with the Pd/3C-SiC junctions, the Ru/3C-SiC Schottky sensors showed higher resolution and better reversibility in the hydrogen concentration range 10000 to 20000 ppm. The SIMS (Secondary Ion Mass Spectrometry), RBS (Rutherford Backscattering Spectrometry) and GIXRD (Glancing Incidence X-ray Diffraction) studies indicated that up to 400 °C there was no formation of ruthenium silicide at the Ru/3C-SiC interface.

Hydrogen energy offers great promise as an energy alternative. Hydrogen technologies can reduce and eliminate the release of carbon dioxide from fossil-fuel combustion, the main cause of global warming. One of the main challenges is hydrogen storage. Storing hydrogen in the solid-state hydride form holds a volumetric advantage over compressed and liquid hydrogen states. Solid hydrogen storage systems also have features of low-pressure operation, compactness, safety, tailorable delivery pressure, excellent absorption /desorption kinetics, modular design for easy scalability, and long cycle life.

In this paper, solid hydrogen storage systems (such as portable power canisters, lightweight fiber wrapped vessels, and aluminum tubular vessels, developed by Texaco Ovonic Hydrogen Systems LLC) will be discussed. A system of four canisters each storing approximately 80 grams of reversible hydrogen is shown to run a 1 kW PEM fuel cell for more than 247 minutes at full power. Canisters show no plastic deformation after more than 500 charge/discharge cycles. The measured strain on canister surfaces indicates that DOT stress limits are not exceeded. The canisters are in the early commercialization stage for uninterrupted power supply (UPS) and auxiliary power unit (APU) applications.

A lightweight fiber-wrapped vessel engineered with metal hydride and internal heat exchanger is being developed for onboard applications. At the system level, the vessel has a volumetric energy density of 50 grams of hydrogen per liter and a gravimetric density of 1.6 wt.%. The vessel is capable of storing 3 kg of hydrogen with a fast refueling capability. Ninety percent of the storable hydrogen can be refueled in 10 minutes at 1500 psig. The vessel can easily release the hydrogen at a rate of 350 slpm at 70°C.

Aluminum tubular vessels are being designed and tested for bulk storage and infrastructure applications including stationary power, hydrogen shipment and hydrogen service stations. The tubular vessel dimensions may be designed for specific applications. For example, a tubular vessel 6 inches in diameter and 62 inches in length can store up to 1 kg of hydrogen.

TiO2 is well known as a prototype photocatalyst for water dissociation. To understand the mechanism of its photocatalytic water dissociation we performed first-principles calculations. We find that the surface of the catalytically favorable (TiO) termination is very different from the physically favorable (oxygen) termination. The calculated surface energy of the catalytically favorable (TiO) termination is about 10 times larger than that of the physically favorable (oxygen) termination. Analysis of the surface band structure suggests that while O-vacancies are intrinsic active sites for water dissociation into H2 and O2 gas, they are not essential for photocatalytic water dissociation. We also find that carbon impurities decrease the band-gap of TiO2, in agreement with previously reported experimental results. Moreover, we identify the origin of the arcane “double band gap” in carbon doped TiO2. The two onsets seen in the photoabsorption spectrum result from excitations from two of three C p-states within the band gap, not from domains of different composition.

Effect of heat treatment on the properties and microstructure of non-stoichiometric Ti-Mn based hydrogen storage alloys were investigated. The results were presented that the hydrogen storage capacity was increased and the width of P-C-T Plateau extended, but the slope of plateau increased after heat treatment. Through SEM, EDS and XRD analysis, it was found that the crystal parameters and cell volume was increased, meanwhile the composition homogeneity effectively enhanced and the content of C15 phase decreased after heat treatment. The accretion of slope of plateau would be related to the ratio of valence electron/atom of the alloys.

Hydrogen absorption and desorption properties of C14 Laves NiTiZr-NiVNb and NiTiZr-NiVZr pseudo-binary alloys were investigated by using the Sieverts' apparatus, XRD and the hydrogen analyzer. The hydrogen capacity and the 50% hydrogen desorption temperature, Td, of the C14 Laves NiTiZr alloy is 1.5 (H/M) and 850 K, respectively. On the other hand, the hydrogen capacity of the C14 NiVNb alloy is 0.2 H/M. In the Ni(TiZr)1−x(VNb)x pseudo-binary system, the hydrogen capacity of the alloys is decreased with increasing x, but the 50% hydrogen desorption temperature is almost constant. The substitution of VNb reduces the hydrogen absorption capacity of the C14 Laves NiTiZr alloy. The hydrogen desorption temperature of Ni(Ti1−xVx)Zr alloy is reduced to 580 K without serious decrease of the hydrogen capacity with increasing x.

Desirable properties of hydrogen storage in materials include mainly, high hydrogen capacity, high number of hydride / dehydride cycles, low temperature of dissociation and microstructural stability. Hydrogen storage can proceed from the gas phase as well as during cathodic charging.

The use of nanocrystalline Mg powder without and with 2 mol% Nb2O5 catalyst as an electrode material for electrochemical hydrogen charging processes in a 6M KOH electrolyte was studied. A strong influence of the compaction parameters and the current density but no influence of the catalyst on the hydrogenation behavior was observed. However, a strong influence of the catalyst on the hydrogen overpotential was observed and is assumed to result into a change of the electrochemical surface reaction. The addition of graphite and PTFE to the Mg/Nb2O5electrodes improves the charging kinetic as well as the hydrogen content up to 1 wt.% hydrogen.

Zr-based metallic glasses are known to absorb high amounts of hydrogen, but exhibiting less severe embrittlement than their crystalline counterparts; therefore, they might be useful for hydrogen storage application. In order to understand kinetics of hydrogen absorption and desorption in more detail, data on hydrogen diffusion are necessary. The aim of this paper is to present hydrogen diffusivities in melt-spun amorphous Zr69.5Cu12Ni11Al7.5 alloys.

Hydrogen charging was performed electrochemically in a 2:1 glycerin-phosphoric acid electrolyte. Hydrogen contents were measured by a microbalance with accuracy of ±1 μg as well as by LECO. Diffusivities of hydrogen atoms were measured at different temperatures by the technique of Nuclear Magnetic Resonance (NMR) diffusion in a static fringe field of a superconducting magnet. The diffusion of hydrogen nuclei in an inhomogeneous magnetic field is accompanied by the change of its NMR resonance frequency, which produces motional destruction of the spin echo signal. The analysis of the echo damping allows a model-independent determination of the hydrogen self-diffusion constant, with the low limit of sensitivity D>10−10 cm2/s.

Within the temperature interval between room temperature and 420 K diffusivities in the range between 4×10−8 and 1.2×10−9 cm2/s were observed. The Arrhenius-type temperature dependence indicate a simple classical over-barrier-hopping hydrogen diffusion; the activation energy increases slightly with the hydrogen content. Whereas in a number of metallic glasses hydrogen diffusion is known to increase with the hydrogen content, in Zr69.5Ni12Cu11Al7.5 the opposite effect was observed, at least for hydrogen contents between H/M = 0.2 and 1.2. The results will be compared with other measurements known for Zr-based metallic glasses (e.g., Zr-Ni) and discussed in detail, e.g. in regard to the density of the glass.

We studied the thermodynamics of interstitial Mg:H solid solutions by means of ab-initio electronic structure calculations. Soft pseudopotentials (Troullier-Martins) with non linear core correction and Perdew-Burke-Ernzerhof GGA exchange-correlation functional were employed, in the framework of a DFT plane-wave scheme. We inserted increasing concentrations of interstitial H atoms in the hcp Mg lattice, in both tetrahedral and octahedral positions. We calculated the heat of solution and the volume variation as a function of H concentration. Although the difference in Gibbs free energy is positive at any H concentration above 10−6 at.%, our results show that the enthalpic contribution is negative at any H concentration, therefore locally favouring H clustering. This reflects the existence of a driving force for the subsequent formation of the hydride. The volume deformation was characterized, finding that octahedreal interstitials have a minor effect, while tetrahedral interstitial can induce very large local expansion.

We have extended our previous investigation of the electrical characteristics of a Pd/AlN/Si thin film sensor for varying thicknesses of AlN, from 300–2000Å. The capacitance vs. voltage, C(V), and conductance vs. voltage, G(V), measurements were utilized to investigate the presence of surface states within the Si gap at the AlN/Si interface. Our previous experiments on 500Å AlN did show the presence of interface traps, with an estimated surface density between 8×1014 and 1.5×1015 m−2eV−1 [1]. In our present work we've examined the effect of AlN thickness on the density of these interface traps. The density is dependent on AlN thickness. The thinner devices, 300Å, showed an interface trap density of 20–30×1015 m−2eV−1. The interface trap density decreased with increasing thickness up to 500Å, where the density remained relatively constant at about 1–5×1015 m−2eV−1 for thicknesses up to 2000Å. We have also shown that the interface trap density is independent of annealing.

Hydrogen is called the “ultimate fuel.” It is also the ultimate element. It was born in the Big Bang and almost all of known matter is composed of it. Its condensation into a star, our sun, through fusion, provides us the energy and the photons which power our earth and which we can utilize in the form of photovoltaics to break apart water and generate hydrogen as an energy source on earth.

The hydrogen economy is here. It has been initiated by the electric and hybrid vehicles which depend upon it for their operation through nickel metal hydride batteries and hydrogen as a fuel for the internal combustion engine and by outwitting the Carnot cycle for use as a fuel cell.

I will discuss the complete system needed for the hydrogen economy from generation to storage to infrastructure and use. Any one part of this loop is necessary but not sufficient.

Our global economy is based upon energy and the societal needs for a nonpolluting, non-climate change fuel which does not require strategic military defense as does oil. The transition from fossil fuels to hydrogen is of revolutionary import not only for its societal impact but also for the new materials science that it absolutely requires in all of its aspects. New science and new technologies build much needed new industries, which provide not only jobs but also feedback on our educational system.

Recall that the ages of civilization are known by their materials. Truly, the presentage will be known by the materials that make up the twin pillars of our global economy – energy and information. Therefore, I will address the new science, technology and atomic engineering of the materials so necessary to make positive, realistic and productive this revolutionary transition of energy from its fossil fuel beginnings to the present.

YFe2H4 is a ferromagnetic metal with magnetization higher than the Laves phase parent compound, YFe2. Here, the electronic and magnetic properties of YFe2H4 are studied using density functional calculations, in order to elucidate the reasons for this. The electronic structure of YFe2H4 differs from that of YFe2 both because of the lattice expansion upon hydriding and because of chemical interactions involving H. However, the main reason for the increased magnetization is found to be the lattice expansion.

Thin Palladiun/SiO2 composite membrane supported on porous stainless steel has been fabricated by a novel preparation procedure. SiO2 colloid suspensions with different particle sizes were applied to modify the pore size of the substrate and also form an intermediate SiO2 layer to support the palladium layer. Palladium nuclei were seeded by a chemical vapor deposition process using Pd(F6acac)2 as metal precursor, and then a palladium layer thinner than 10 μm was prepared by electroless plating. The membrane had a hydrogen permeance of 2.7×10−6 mol/m2.s.Pa and a permselectivity of PH2 / PN2 in the range of 300–400 at 773K. The preparation process showed that SiO2 layer had a unique property for palladium adhesion compared with other studied metal oxides. The seeding process by chemical vapor deposition showed this step is significant for the preparation of a defect-free membrane. A novel electroless plating process was also applied using a weak acidic both, which is different from the usually used basic ones containing N2H4. The surface morphology and component of the membrane have been studied by scanning electron micrograph (SEM) and energy-dispersive X-ray analysis (EDX). The permeance and permselectivity of the membrane to hydrogen have bean measured at different temperatures.

In recent years, the development of Ti-doped NaAlH4 as a hydrogen storage material has gained attention because of its large weight percentage of hydrogen (∼5 %) compared to traditional interstitial hydrides. The addition of transition-metal dopants, in the form of Ti-halides, such as TiCl3, dramatically improves the kinetics of the absorption and desorption of hydrogen from NaAlH4. However, the role that Ti plays in enhancing the absorption and desorption of H2 is still unknown. In the present study, 27Al, 23Na, and 1H MAS (Magic Angle Spinning) NMR (Nuclear Magnetic Resonance) has been performed to understand the titanium speciation in Ti-doped NaAlH4. All experiments were performed on a sample of crushed single crystals exposed to Ti during growth, a sample of solvent-mixed 4TiCl3 + 112NaAlH4, a reacted sample of solvent-mixed TiCl3 + 3NaAlH4 with THF, and a reacted sample of ball-milled TiCl3 + 3NaAlH4. The 27Al MAS NMR has shown differences in compound formation between solvent-mixed TiCl3 + 3NaAlH4 with THF and the ball-milled TiCl3 + 3NaAlH4. 27Al MAS NMR of the ball-milled mixture of fully-reacted TiCl3 + 3NaAlH4 showed spectral signatures of TiAl3 while, the solvent-mixed 4TiCl3 + 112NaAlH4, which is totally reacted, does not show the presence of TiAl3, but suggests the existence of Al2O3.

Magnesium carbon nanocomposites for hydrogen storage have been synthesized by ball milling with different amount of benzene, acting as a lubricant. Their microstructure has been studied by X-ray diffraction and scanning electron microscopy, while the hydrogen desorption temperature has been tested by differential scanning calorimetry. Experimental results show that the microstructure after milling, the hydrogenation capabilities of the material and the reactivity with the air are related to the amount of additives. In particular the carbon to benzene ratio seems to play a major role. In fact, with an optimum value of carbon to benzene weight ratio of 1/6, the amount of carbon being 15 wt% of the milled mixture, a decomposition heat equal to 57% of pure MgH2 was measured, even after air manipulation of the sample.

The most common diagnostic tools in studying reversible solid-state hydrogen storage materials involve volumetric or gravimetric approaches. In this study, a mature gas solid analysis technique called Temperature Programmed Reaction (TPR) is presented as an alternative and complementary approach in investigating solid-state hydrogen storage materials. TPR is fast, simple and offers valuable information from a wide range of solid materials. This technique is routinely used to characterize the reduction behavior of metal oxide and sulfide catalysts. In a typical TPR experiment, a sample powder is heated at a constant rate under a non steady-state environment of constant pressure and flow of a hydrogen/inert gas mixture, while monitoring the rate of hydrogen absorption and desorption by a thermal conductivity detector. The principle behind TPR is the high thermal conductivity coefficient of hydrogen when compared to other gases. The detector is sensitive enough that a slight change in hydrogen concentration is reflected by significant changes in the thermal conductivity signal. Hydrogen storage materials exhibit fingerprint type TPR spectra, unique to their composition and structure. Specific rates of hydrogen intake, heats of absorption and desorption as well as extent of activation can be extracted from TPR curves. In addition, multiple absorption and desorption states can be identified from the number of absorption or desorption peaks. Material stability and potential structural or phase changes can also be inferred indirectly. The simplicity and the highly sensitive thermal conductivity measurement provide a number of advantages over the traditional volumetric or gravimetric methods. Metal hydride alloys of AB5-type are used to demonstrate the effectiveness of TPR technique in characterizing hydrogen storage materials.

Perovskite titanates with nominal stoichiometry ABO3+Δ are frequently reported in SOFC literature as having O3 stoichiometry. Such phases often exhibit quite interesting properties, but are not stoichiometric and the structural characterisation is usually not rigorous. Here we demonstrate how oxygen excess can be incorporated in a titanate perovskite-based lattice as crystallographic oxygen shears giving rise to the homologous series La4Srn−4TinO3n+2. The layered structure is lost for the n=12 member (La4Sr8Ti12O38−Δ), although the oxygen excess is accommodated within the perovskite framework in randomly distributed short-range linear defects. This compound was studied as potential fuel electrode due to its high total conductivity and stability in the most reducing conditions.

We have synthesized nanoporous carbon membranes that have monodisperse pores of 4–5 Å. These membranes have excellent size and shape selectivity that makes them an ideal candidate for use as separators in fuel cells. The selectivity of these membranes to gases such as N2, O2 and water gas [carbon monoxide and hydrogen] were measured using a permeation testing unit. These membranes were then tested as separators in fuel cells.

The hydrogen adsorption capacity of commercially available carbon materials with different nanostructures was measured at room temperature using an apparatus based on a volumetric method with an error of less than 0.04 wt% per one gram of sample. The obtained results suggest that nanosutures of the sample influence the hydrogen adsorption capacity. To confirm this hypothesis, we prepared nanostructured graphite from graphite powder using a mechanical milling process at a pressure of 2.0 × 10−4 Pa. The untreated graphite adsorbed 0.02wt% of hydrogen at 6 MPa at room temperature, while 0.20 − 0.25 wt% of hydrogen can be repeatedly adsorbed by the nanostructured graphite. Measurements of the hydrogen adsorption rate at constant pressure and pore-size distribution imply that the hydrogen molecules are adsorbed through a diffusion process in pores with a diameter less than 1 nm.

The investigation of many stoichiometric variations involving large numbers of combinations of elements offers a means to discover a hydride with optimal properties. We introduce the use of spatially resolved infrared imaging as a high throughput hydrogen storage candidate screening technique. Analysis is presented of a sample that consists of 16 separate Mg-Ni-Fe ternary pads and 32 Mg-Ni or Mg-Fe binary pads. Hydrogen sorption related emissivity changes observed indicate a substantial decrease in hydriding temperatures, which sensitively depends on composition.