Hydrogen-containing Materials Research Articles

Dependence of a Hydrogen Buffer Layer on the Properties of Top-Gate IGZO TFT.

In this paper, the effect of a buffer layer created using different hydrogen-containing ratios of reactive gas on the electrical properties of a top-gate In-Ga-Zn-O thin-film transistor was thoroughly investigated. The interface roughness between the buffer layer and active layer was characterized using atomic force microscopy and X-ray reflection. The results obtained using Fourier transform infrared spectroscopy show that the hydrogen content of the buffer layer increases with the increase in the hydrogen content of the reaction gas. With the increase in the hydrogen-containing materials in the reactive gas, field effect mobility and negative bias illumination stress stability improve nearly twofold. The reasons for these results are explained using technical computer-aided design simulations.

Applied electric field to repair metal defects and accelerate dehydrogenation

Repairing metal micro-defects at the atomic level is very challenging due to their random dispersion and difficulty in identification. At the same time, the interaction of hydrogen with metal may cause hydrogen damage or embrittlement, endangering structural safety. As a result, it is critical to speed up the dehydrogenation of hydrogen-containing materials. The applied electric field can repair the vacancy defects of the material and accelerate the dehydrogenation of the hydrogen-containing metal. The influence of the external environment on the diffusion coefficient of hydrogen in polycrystalline metals was researched using molecular dynamics in this article, and the mechanism of hydrogen diffusion was investigated. Simultaneously, the mechanical characteristics of Fe3Cr alloy were compared during typical heat treatment and electrical treatment. The effect of temperature, electric field strength, and electric field direction on the diffusion coefficient was investigated using orthogonal test analysis. The results demonstrate that temperature and electric field strength have a significant impact on the diffusion coefficient. The atom vibrates violently as the temperature rises, breaking past the diffusion barrier and completing the atomic transition. The addition of the electric field adds extra free energy, decreases the atom’s activation energy, and ultimately enhances the atom’s diffusion coefficient. The repair impact of vacancy defects under electrical treatment is superior to that of typical annealing treatment for polycrystalline Fe3Cr alloy. The electric field can cause the dislocation to migrate, increasing the metal’s toughness and plasticity. This research serves as a useful reference for the electrical treatment of metal materials and offers a method for the quick dehydrogenation of hydrogen-containing materials.

Inelastic neutron scattering: A unique tool to study hydrogen in materials

Inelastic neutron scattering (INS) spectroscopy can measure the vibrational spectra of materials on the whole range of vibrational motions (0–4400 cm-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-1}$$\\end{document}) and effectively open up the field of neutron spectroscopy. Unlike optical spectroscopy, INS is a technique mainly used to study hydrogen-containing materials due to the high cross section of hydrogen and the lack of selection rules. The VISION spectrometer at the SNS in Oak Ridge National Laboratory has a flux at low energy transfers up to 40 times over its predecessors and has unprecedented sensitivity. Neutrons penetrate easily through materials, metals in particular, making complex sample environments and gas dosing relatively easy. Comparison of the INS spectra with computer models is rigorous and necessary to interpret INS data. This paper presents examples of the technique’s unique capabilities for studying metal hydrides and molecular hydrogen in confinement.Graphical abstract

Detailed studies of the processes in low energy H irradiation of Li and Li-compound surfaces

We have used a combination of pico-to-nano temporal/spatial scale computational physics and chemistry modeling of plasma–material interfaces in the tokamak fusion plasma edges to unravel the evolving characteristics, not readily accessible by empirical means, of lithium-, oxygen-, and hydrogen-containing materials of plasma-facing components under irradiation by hydrogen and its isotopes. In the present calculation, amorphous lithium compound surfaces containing oxygen, Li2O, and LiOH were irradiated by 1–100 eV particles at incident angles on the surface ranging from perpendicular to almost grazing angles. Consequential surface processes, reflection, retention, and sputtering were studied at “the same footing” and compared to earlier results from amorphous Li and LiH surfaces. The critical role of charging dynamics of lithium, oxygen, and hydrogen atoms in the surface chemistry during hydrogen-fuel irradiation was found to drive the kinetics and dynamics of these surfaces in unexpected ways that ultimately could have profound effects on fusion plasma confinement behavior and surface erosion.

Failure analysis of corroded heat exchanger CuNi tubes from a geothermal plant

This study examined the premature failure of cupronickel (CuNi10Fe) tubes in a shell-and-tube heat exchanger after five months of service. An investigation to identify the root cause of the tube burst was carried out using macroscopic and microscopic inspection, chemical analysis, and mechanical analysis. The optical microscopy (OM) and scanning electron microscopy (SEM) evaluation revealed crack propagation characterized by pits and inclusions at the tube surface. This was due to the diffusion of hydrogen ions into the material from the hydrogen sulfide (H2S) rich geothermal environment. Furthermore, high tensile residual stresses of 172 MPa were recorded in the failed tube, leading to stress cracking in hydrogen-containing material. Additionally, the high sulfide content in corroded water and condensate samples suggests that the leading cause of tube rupture was through hydrogen embrittlement and sulfide stress cracking mechanism in the presence of hydrogen sulfide. Therefore, the use of laser cladding to protect tubes using functionally graded materials is recommended to mitigate degradation in aggressive environments, through careful material selection and additional water treatment to eliminate the contaminants.

Neutron diffraction probing hydrogen in monoclinic H2VOPO4

Light hydrogen atoms are resolvable with neutrons; however, the massive incoherent background inhibits the diffraction quality. To improve the signal, isotope treatment by deuteration becomes a prerequisite for a successful crystallographic understanding of hydrogen-containing materials by neutron diffraction. Thanks to the low-background and high-resolution time-of-flight neutron diffractometer, this work demonstrates a direct and successful measurement of high-quality neutron diffraction patterns of H2VOPO4 powders, a precursor of a high-capacity alkali-ion battery cathode. The Rietveld refinement identifies the hydrogen coordinates, occupancy, and thermal parameters in the H2VOPO4 lattice. The result highlights the unique capability of neutron diffraction for the structure characterization of hydrogen-containing materials, potentially without requiring costly and possibly artifact-inducing deuteration for neutron diffraction.

Mapping Hydrogens in Hydrous Materials

Hydrous materials such as clays, cements, hydroxyapatite, and metal hydroxides have been known and extensively used since antiquity. However, experimental elucidation of hydrogen in hydrous materials remains challenging due to the intrinsic insensitivity, limited accessibility, sample damage, or poor spectral resolution of many characterization methods. 1H solid-state NMR spectroscopy has evolved into an ideal site-specific characterization tool of hydrogen-containing materials, but its current application in hydrous materials is hampered by the low resolution of 1H NMR spectra in the solid state due to the presence of intense dipolar coupling networks and a narrow 1H chemical shift range. Herein, a significant advance in the characterization of hydrogens in hydrous materials is reported. A combination of magic-angle spinning (MAS) NMR, moderate 2H substitution, and high magnetic fields has unlocked the capacity of identifying many chemically similar while crystallographically distinct hydrogen sites in a prototypical hydrous material Y4(OH)10Br2·3H2O (LYH-Br) by 1D 1H solid-state NMR experiments. 1H NMR peaks were first tentatively assigned in accordance with the density functional theory (DFT) calculation results, and the assignment was further refined by 2D 1H–89Y heteronuclear correlation (HETCOR) and 1H–1H double-quantum (DQ) MAS NMR data. The order of 1H chemical shift (δiso) values provides valuable information on the relative strength of hydrogen bond for ten hydroxide hydrogen sites. The power of very high spectral resolution is further described by observing all triple-quantum (TQ) coherences in the 2D 1H–1H TQ MAS NMR spectrum, in which all spatial proximities among three hydrogen sites are resolved. This demonstration of the very high spectral resolution obtained in 1D and 2D 1H solid-state NMR experiments illustrates how scientists in various communities can now study the multiple hydrous species of hydrous materials and obtain previously inaccessible fine structural information.

Технология модификации древесины березы для создания нейтронозащитных материалов

The article considers a method for producing neutron shielding materials based on modified birch wood. It is known that shielding materials based on polyethylene with boron addition are widely used in the nuclear industry, medicine and the military-industrial complex to create protection against neutron radiation. Due to the high hydrogen content, their use makes it possible to protect objects from the effects of fast neutrons, and thermal neutrons are effectively contained due to the presence of boron atoms in the protective screens. Wood is also a hydrogen-containing material, therefore, it is of scientific and practical interest to create and study the properties of neutron shielding materials based on wood. The most expedient is the creation of neutron shielding materials from hardwood, which have a high specific density and, accordingly, a high content of hydrogen per unit volume. It is possible to increase the hydrogen content per unit volume of wood and, accordingly, to reduce the thickness of the protective layer due to the compaction of wood by the method of flat (singleaxis) pressing. The main condition for obtaining high-strength and form-resistant pressed wood is the preservation of its microstructure (without damage) during pressing. It has been theoretically found that the optimal pressing stage, at which the lowest percentage of microfractures in wood is observed, should not exceed 50 %. In the experimental part of the work, birch lumber was used for the production of an experimental neutron shielding material, radial sawn with a length of 200 mm, a width of 100 mm, and a thickness of 80 mm to obtain ready-made neutron shielding materials with a thickness of 40 mm, which is equivalent to a polyethylene shielding thickness of 26.8 mm. It is known that during flat pressing bursting forces occur in wood, which can lead to cracks, destruction of edges, buckling, delamination, and a decrease in the uniformity of the density distribution. The bursting force acts in the direction perpendicular to the action of the applied load. Therefore, in the manufacture of a neutron shielding composite material, it is necessary to use press molds (with side stops) that stop the impact of the bursting force. The design parameters of the press molds and pressing modes are determined taking into account the resistance caused by the friction forces of the wood against the side walls of the press mold. The design of a press mold that provides the production of a neutron shielding material of specified properties from wood is presented.

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

A spin-contrast-variation neutron powder diffractometry technique that extracts the structure factor of hydrogen atoms, i.e. the contribution of hydrogen atoms to a crystal's structure factor, has been developed. Crystals of L-glutamic acid were dispersed in a D-polystyrene matrix containing 4-methacryloyloxy-2,2,6,6,-tetramethyl-1-piperidinyloxy to polarize their proton spins dynamically. The intensities of the diffraction peaks of the sample changed according to the proton polarization, and the structure factor of the hydrogen atoms was extracted from the proton-polarization-dependent intensities. This technique is expected to enable analyses of the structures of hydrogen-containing materials that are difficult to determine with conventional powder diffractometry.

Selection of reagent ratio for hydrogen production via Al nanopowder oxidation

In the present paper, Al is considered as a basic material for hydrogen production from water because of its high performance, availability, and environmental safety of its reaction products. Here we report the results of experimental trials on the oxidation of Alex-grade Al nanopowder by water when heated and stirred. The plots of pressure and temperature versus Al oxidation time in a high-pressure reactor are given. We show the advantages of hydrogen extraction from hydrogen-containing materials via the oxidation of metal powders. An optimum mass ratio of Al nanopowder to water at which the oxidation reaction takes place to release hydrogen has been identified by varying the reagent ratio. It can be concluded at this point of the study that it is advisable to maintain the H2O-to-Al nanopowder ratio of 11:1 for hydrogen production. Hydrogen resulted from this reaction can be used to supply small-scale power packs based on hydrogen FC.

Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion

Following the E-MRS (European Materials Research Society) fall meeting 2019, Symposium L, this Special Issue of Inorganics, entitled “Beyond Hydrogen Storage—Metal Hydrides as Multifunctional Materials for Energy Storage and Conversion”, is dedicated to the wide range of emerging energy-related inorganic hydrogen-containing materials [...]

Quantitative Analysis of Hydrogen in High-Hydrogen-Content Material of Magnesium Hydride via Laser-Induced Breakdown Spectroscopy.

An analytical approach that can rapidly determine a wide range of hydrogen concentration in solid-state materials has been recently demanded to contribute to the hydrogen economy. This study presents a method for estimating hydrogen concentrations ranging from 0.2 to 7.6 mass % via laser-induced breakdown spectroscopy (LIBS) in a few seconds, with an improvement in the upper limit of determination (7.6 mass %) by approximately 1.3 times compared with a previous work (5.7 mass %). This extension of the determinable concentration range was achieved by measuring the emission intensity at 656.28 nm from the sample in a helium atmosphere at 3000 Pa under focused laser irradiation and by reducing the water residues in both the sample and gas line of the LIBS system. The as-determined hydrogen concentrations in magnesium hydride (MgH2) samples agreed well with those estimated through inert gas fusion/gas chromatography. The calibration curve for LIBS analysis was acquired by measuring the emission intensity at 656.28 nm of standard Mg/MgH2 mixtures containing various hydrogen concentrations (0, 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 7.6 mass %). Results indicated that the proposed LIBS-based method is applicable to the rapid quantitative analysis of hydrogen in hydrogen-containing material of MgH2.

Adjusting the interface structure of graphdiyne by H and F co-doping for enhanced capacity and stability in Li-ion battery

The 18–C triangular ring structure of graphdiyne (GDY) can form three-dimensional channel between layers and make GDY an excellent anode material for lithium ion batteries (LIBs). The stable solid electrolyte interface (SEI) film and strong C–F bond formed by fluoride can forcefully enhance the cycle stability in LIBs. Additionally, the stable synthesis of hydrogen-containing carbon material reduces cost and the effective lithium storage of H increases specific capacity. Herein, we propose a strategy of H and F positioning balanced co-doped GDY, combining the lithium storage contributions of H and F elements and achieving an extraordinarily high capacity of 2050 ​mA ​h g−1 at 50 ​mA ​g−1 and only 23% reduction after even 8000 cycles. The fibrous network porous structure can be formed and generate excellent electrolyte infiltration and interface stability with SEI film when H and F is evenly co-doped. This work provides approach to interface structure adjustment that effectively improved lithium storage stability. Besides, the combination approach of positioning substitution and co-doping contributes to high lithium storage capacity and provides reference for elements co-doping.

Study of the hydration level in proton conducting oxides using neutron diffraction with polarization analysis

We report results from neutron diffraction with polarization analysis of the effect of In dopant level on the hydrogen concentration in hydrated samples of the proton conducting perovskite type oxide BaZr1−xInxO3−x/2 with x = 0, 0.175, 0.20, 0.225, 0.25, and 0.275. Analysis of the neutron data establishes a trend of increasing hydrogen concentration, which is comparable to that obtained from thermogravimetric measurements on the same samples, as well as an increased unit-cell size and local structural disorder as a function of increasing In dopant level. These results encourage further use of neutron diffraction with polarization analysis as a non-destructive technique for the determination of the total hydrogen concentration, and structural properties, of proton conducting oxides as well as other hydrogen-containing materials.

Desktop NMR and Its Applications From Materials Science To Organic Chemistry.

NMR spectroscopy is an indispensable method of analysis in chemistry, which until recently suffered from high demands for space, high costs for acquisition and maintenance, and operational complexity. This has changed with the introduction of compact NMR spectrometers suitable for small-molecule analysis on the chemical workbench. These spectrometers contain permanent magnets giving rise to proton NMR frequencies between 40 and 80 MHz. The enabling technology is to make small permanent magnets with homogeneous fields. Tabletop instruments with inhomogeneous fields have been in use for over 40 years for characterizing food and hydrogen-containing materials by relaxation and diffusion measurements. Related NMR instruments measure these parameters in the stray field outside the magnet. They are used to inspect the borehole walls of oil wells and to test objects nondestructively. The state-of-the-art of NMR spectroscopy, imaging and relaxometry with compact instruments is reviewed.

A neutron detector that is insensitive to attendant γ rays

A neutron detector is described, whose operating principle is based on detecting charge-transfer effects of secondary recoil protons produced in hydrogen-containing materials under exposure to primary neutrons. The physical mechanism of the operation of this detector is presented and its sensitivity is determined as a function of the neutron energy. The design of a detector that is insensitive to attendant γ rays is proposed. The serviceability of the detector has been confirmed experimentally. The detector may find application to tests in mixed fields of γ rays and neutrons.

The hydrogen anomaly in neutron Compton scattering: new experiments and a quantitative theoretical explanation

No consensus has been reached so far about the hydrogen anomaly problem in Compton scattering of neutrons, although strongly reduced H cross-sections were first reported almost 20 years ago. Over the years, this phenomenon has been observed in many different hydrogen-containing materials. Here, we use yttrium hydrides as test objects, YH2, YH3, YD2 and YD3, Y(HxD1−x)2 and Y(HxD1−x)3, for which we observe H anomalies increasing with transferred momentum q. We also observe reduced deuteron cross-sections in YD2 and YD3 and have followed those up to scattering angles of 140° corresponding to high momentum transfers. In addition to data taken using the standard Au-197 foils for neutron energy selection, the present work includes experiments with Rh-103 foils and comparisons were also made with data from different detector setups.The H and D anomalies are discussed in terms of the different models proposed for their interpretation. The ‘electron loss model’ (which assumes energy transfer to excited electrons) is contradicted by the present data, but it is shown here that exchange effects in scattering from two or more protons (or deuterons) in the presence of large zero-point vibrations, can explain quantitatively the reduction of the cross-sections as well as their q-dependence. Decoherence processes also play an essential role. In a scattering time representation, shake-up processes can be followed on the attosecond scale. The theory also shows that large anomalies can appear only when the neutron coherence lengths (determined by energy selection and detector geometry) are about the same size as the distance between the scatterers.

Preparation of Pd-Co-based nanocatalysts and their superior applications in formic acid decomposition and methanol oxidation.

Formic acid (FA) and methanol, as convenient hydrogen-containing materials, are most widely used for fuel cells. However, using suitable and low-cost catalysts to further improve their energy performance still is a matter of great significance. Herein, PdCo and PdCo@Pd nanocatalysts (NCs) are successfully prepared by the facile method. Pd 3d binding energy decreases due to the presence of Co. Consequently, PdCo@Pd NCs exhibit high catalytic activity and selectivity toward FA dehydrogenation at room temperature. The gas-generation rate at 30 min is 65.4 L h(-1) g(-1) . PdCo/C has the worst catalytic performance in this reaction, despite the fact that it has a high gas-generation rate in the initial 30 min. Furthermore, both PdCo and PdCo@Pd NCs have enhanced electrocatalytic performance toward methanol oxidation. Their maximum currents are 966 and 1205 mA mg(-1) , respectively, which is much higher than monometallic Pd/C.

Explosion Power and Pressure Desensitization Resisting Property of Emulsion Explosives Sensitized by MgH2

Due to low detonation power and pressure desensitization problems that traditional emulsion explosives encounter in utilization, a hydrogen-based emulsion explosives was devised. This type of emulsion explosives is sensitized by hydrogen-containing material MgH2, and MgH2 plays a double role as a sensitizer and an energetic material in emulsion explosives. Underwater explosion experiments and shock wave desensitization experiments show that an MgH2 emulsion explosives has excellent detonation characteristics and is resistant to pressure desensitization. The pressure desensitization–resistant mechanism of MgH2 emulsion explosives was investigated using scanning electron microscopy.

Nuclear quantum effects inab initiodynamics: Theory and experiments for lithium imide

Owing to their small mass, hydrogen atoms exhibit strong quantum behavior even at room temperature. Including these effects in first principles calculations is challenging, because of the huge computational effort required by conventional techniques. Here we present the first ab-initio application of a recently-developed stochastic scheme, which allows to approximate nuclear quantum effects inexpensively. The proton momentum distribution of lithium imide, a material of interest for hydrogen storage, was experimentally measured by inelastic neutron scattering experiments and compared with the outcome of quantum thermostatted ab initio dynamics. We obtain favorable agreement between theory and experiments for this purely quantum mechanical property, thereby demonstrating that it is possible to improve the modelling of complex hydrogen-containing materials without additional computational effort.