Quantitative Analysis Of Hydrogen Research Articles

Revealing the role of high-valence elementary substitution in the hydrogen-induced Mottronic transitions of vanadium dioxide

Electron-doping Mottronics within correlated vanadium dioxide (e.g., VO2) opens up a paradigm to abruptly regulate the Mottronic phase transitions via adjusting the d-orbital occupancy and configuration. Nevertheless, the potential impact of high-valence elementary substitution in the hydrogen-associated Mottronic transitions of VO2 is yet unclear. Herein, we demonstrate the role of high-valence elementary substitution (e.g., W6+) in regulating the hydrogen-triggered Mottronic transitions of VO2, assisted by quantitative hydrogen analysis using the nuclear reaction analysis. Substituting vanadium with a high-valence transitional metal (e.g., W6+) within doped-VO2 largely reduces the hydrogen incorporation (e.g., ∼1.61 × 1021 cm−3 in H0.06V0.95W0.05O2) compared to the intrinsic VO2 (e.g., ∼1.08 × 1022 cm−3 in H0.35VO2) under the low temperature hydrogenation process. Therefore, in contrast to hydrogen-induced electron localization of intrinsic VO2 upon low-temperature hydrogenation, only the hydrogen-triggered metallic state is observed within the hydrogen-associated phase diagram of WxV1-xO2, as further probed by the near-edge x-ray absorption fine structure analysis and x-ray photoelectron spectroscopy. The present work reveals the overlooked role associated with the donor substitutions that largely influences the competitive equilibrium between the two rival hydrogen-induced Mottronic transitions within VO2 toward either the metallic or the highly insulating phase.

Towards quantitative analysis of deuterium absorption in ferrite and austenite during electrochemical charging by comparing cyclic voltammetry and cryogenic transfer atom probe tomography

Hydrogen embrittlement mechanisms of steels have been studied for several decades. Understanding hydrogen diffusion behavior in steels is crucial towards both developing predictive models for hydrogen embrittlement and identifying mitigation strategies. However, because hydrogen has a low atomic mass, it is extremely challenging to detect by most analytical methods. In recent years, cryogenic-transfer atom probe tomography (APT) of electrochemically-deuterium-charged steels has provided invaluable qualitative analysis of nanoscale deuterium traps such as carbides, dislocations, grain boundaries and interfaces between ferrite and cementite. Independently, cyclic voltammetry (CV) has provided valuable analysis of bulk hydrogen diffusion in steels. In this work, we use a combination of CV and cryogenic-transfer APT for quantitative analysis of deuterium pickup in electrolytically charged pure Fe (ferrite) and a model austenitic Fe18Cr14Ni alloy without any second phase. The high solubility and low diffusivity of hydrogen in austenite versus ferrite and potential influence of oxide layer are highlighted to result in clear observable signatures in CV and cryogenic-transfer APT results. The remaining challenges and pathway for enabling quantitative analysis of hydrogen pick up in steels is also discussed.

Quantitative analysis of hydrogen and fatty acid from homoacetogenesis and optimization of glycerol fermentation condition

Glycerol is inevitably produced as a byproduct during biological diesel oil production and petrochemical production. This study was aimed to investigate the effects of CO2 concentration in headspace (CO2%), hydraulic retention time (HRT), organic loading rate (OLR) on H2 consumption and volatile fatty acids (VFA) production as well as the role of homoacetogenesis during glycerol fermentation. For the first time, a homoacetogenesis quantification formula was established to calculate H2 consumption and acetic acid (HAc) production during glycerol fermentation, namely, [H2] = [EtOH]–2[PrOH]+3[HAca]–4[HAcb]+4[HBu]. H2 consumed by homoacetogenesis accounted for 6.73%–76.10% of the total H2, and HAc produced from homoacetogenesis occupied at least 30.91% of total HAc. The production of propyl alcohol had a negative effect on homoacetogenesis. The interaction between OLR and CO2% had an extremely significant effect on both VFA production and H2 yield. The maximum VFA production and H2 yield were 4454.638 mg/d and 0.396 mol-H2/mol-glyceroladd, respectively.

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.

Quantitative analysis of hydrogen and chalcogen bonds in two pyrimidine-5-carbonitrile derivatives, potential DHFR inhibitors: an integrated crystallographic and theoretical study.

Two potential bioactive pyrimidine-5-carbonitrile derivatives have been synthesized and characterized by spectroscopic techniques (1H and 13C-NMR) and the three dimensional structures were elucidated by single crystal X-ray diffraction at low temperature (160 K). In both structures, the molecular conformation is locked by an intramolecular C–H⋯C interaction involving the cyano and CH of the thiophene and phenyl rings. The intermolecular interactions were analyzed in a qualitative manner based on the Hirshfeld surface and 2D-fingerprint plots. The results suggest that the phenyl and thiophene moieties have an effect on the crystal packing. For instance, the chalcogen bonds are only preferred in the thiophene derivative. However, both structures uses a common N–H⋯O hydrogen bond motif. Moreover, the structures of 1 and 2 display 1D isostructurality and molecular chains stabilize by intermolecular N–H⋯O and N–H⋯N hydrogen bonds. The nature and extent of different non-covalent interactions were further characterized by the topological parameters derived from the quantum theory of atoms-in-molecules approach. This analysis indicates that apart from N–H⋯O hydrogen bonds, other non-covalent interactions are closed-shell in nature. A strong and linear N–H⋯O hydrogen bond shows intermediate bonding character between shared and closed-shell interactions. The molecular docking analysis suggests that both compounds display potential inhibitory effect against the dihydrofolate reductase (DHFR) enzyme from humans and Staphylococcus aureus.

Quantitative hydrogen analysis through time of flight-elastic recoil detection analysis using medium energy ions

Quantitative hydrogen analysis is a useful tool in various fields, such as the energy, catalysts, and semiconductor fields, because the quality of materials or devices strongly depends on their hydrogen concentrations. To analyze the concentration of hydrogen quantitatively, the elastic recoil detection analysis (ERDA) method is widely used. In this report, the number fraction of hydrogen in silicon nitride was analyzed using a simple time-of-flight ERDA method over a depth range of 25 nm from the surface without the use of a stopping foil, an additional analyzer, or charged particle optics. The number fractions of the other elements (silicon and nitrogen) in the sample were also analyzed through backscattering measurements.

Experimental and theoretical investigations of a proton transfer supramolecular adduct, aminoguanidinium p-nitrophenolate: p-nitrophenol

Single crystals of aminoguanidinium p-nitrophenolate: p-nitrophenol (AGPNP) were grown by slow-evaporation method and the crystal structure of AGPNP was confirmed by Single crystal X-ray diffraction analysis. Spectral analyses such as FT-IR, 1H NMR and 13C NMR were carried out in order to detect the functional groups and find out the different kinds of protons and carbons. Optical transmittance and band gap of AGPNP were investigated through both UV-NIR and Frontier Molecular Orbital analyses. The HOMO-LUMO energy gap was found to be 3.242 eV. A quantitative analysis of hydrogen bonding interactions as well as various atom...atom contacts was carried out using Hirshfeld surface analysis. It shows that the crystal surface was dominated by O⋯H/H⋯O interactions with high contribution of 38%.Optimized geometry shows that NH⋯O and OH⋯O hydrogen bonding interactions were responsible for charge delocalization within the moieties. The existence of various hyperconjugative interactions and charge delocalization were analysed using Natural Bond Orbital analysis. Mulliken charge analysis also reveals the occurrence of hydrogen bonds. Proton transfer mechanism was confirmed by molecular electrostatic potential analysis. It is found that the calculated first order hyperpolarizability of AGPNP is 43.6 times higher than that of urea at B3LYP/6-311 + G(d,p) level of theory.

Development of slew-rate-limited time-over-threshold (ToT) ASIC for a multi-channel silicon-based ion detector

High-resolution Elastic Recoil Detection Analysis (HERDA), which consists of a 90̂ sector magnetic spectrometer and a position-sensitive detector (PSD), is a method of quantitative hydrogen analysis. In order to increase sensitivity, a HERDA system using a multi-channel silicon-based ion detector has been developed. Here, as a parallel and fast readout circuit from a multi-channel silicon-based ion detector, a slew-rate-limited time-over-threshold (ToT) application-specific integrated circuit (ASIC) was designed, and a new slew-rate-limited ToT method is proposed. The designed ASIC has 48 channels and each channel consists of a preamplifier, a slew-rate-limited shaping amplifier, which makes ToT response linear, and a comparator. The measured equivalent noise charges (ENCs) of the preamplifier, the shaper, and the ToT on no detector capacitance were 253±21, 343±46, and 560±56 electrons RMS, respectively. The spectra from a 241Am source measured using a slew-rate-limited ToT ASIC are also reported.

21‐3: Reliability of Coplanar Oxide TFTs : Analysis and Improvement

We confirm that the PBTS instability of coplanar InGaZnO TFTs can be improved through the minimization of Non‐Bridging Oxygen Hole Centers (NBOHC) and optimization of hydrogen passivation in the GI/ACT interface region. The quantitative analysis of hydrogen and oxygen in each region are obtained from physical property measurements. Trap density in GI/ACT interface layer is obtained by photonic capacitance‐voltage measurements which are correlated with PBTS characteristics. A decrease of under coordinated bonding states lessens electron trap density, which brings improvement in PBTS from Vth = 2.61V to 0.21V by process optimization.

Correlations for calculating heat transfer of hydrogen pool boiling

Understanding the heat transfer characteristics of hydrogen pool boiling as well as constructing reliable correlations to guide the boiling heat transfer analysis is of significance to the applications of liquid hydrogen (LH2). In the present paper, the available hydrogen experimental data in literature are summarized and analyzed. Based on these data, several existing correlations aiming at different boiling regimes are evaluated or modified in order to realize the quantitative analysis of hydrogen boiling heat transfer. After sufficient comparison studies, several improved correlations for nucleate boiling, critical heat flux (CHF) and minimum heat flux (MHF) are proposed. Moreover, a complete set of correlations for hydrogen boiling heat transfer are summarized and subsequently a predicted hydrogen boiling curve is constructed. The results show that heat flux in the nucleate boiling regime is approximately a function of ΔT2.5. For the calculation of hydrogen film boiling, Breen & Westwater correlation seems to be appropriate for revealing the heat transfer characteristics no matter what heater geometry is used. For the hydrogen boiling under 0.1 MPa condition, heat fluxes at onset of nucleate boiling (ONB), CHF and MHF are in the order of 10 W/m2, 105 W/m2 and 103 W/m2, respectively, and the corresponding wall superheats are approximately 0.1 K, 3 K and 4 K. In addition, pressure effect on hydrogen boiling heat transfer is investigated, and it shows pressure has a significant influence on MHF while a little effect on the heat fluxes in liquid natural convection and film boiling regimes. CHF of hydrogen increases with the increase of system pressure firstly and then decreased with further pressure increase. The maximum of CHF locates at about P/Pc = 0.35. Generally, the present study is beneficial to understand the boiling heat transfer characteristics of hydrogen, and the summarized correlations could provide researchers with reliable mathematical tools to conduct the boiling heat transfer analysis of hydrogen systems.

Quantitative analysis of hydrogen in SiO2/SiN/SiO2 stacks using atom probe tomography

We have demonstrated that it is possible to reproducibly quantify hydrogen concentration in the SiN layer of a SiO2/SiN/SiO2 (ONO) stack structure using ultraviolet laser-assisted atom probe tomography (APT). The concentration of hydrogen atoms detected using APT increased gradually during the analysis, which could be explained by the effect of hydrogen adsorption from residual gas in the vacuum chamber onto the specimen surface. The amount of adsorbed hydrogen in the SiN layer was estimated by analyzing another SiN layer with an extremely low hydrogen concentration (<0.2 at. %). Thus, by subtracting the concentration of adsorbed hydrogen, the actual hydrogen concentration in the SiN layer was quantified as approximately 1.0 at. %. This result was consistent with that obtained by elastic recoil detection analysis (ERDA), which confirmed the accuracy of the APT quantification. The present results indicate that APT enables the imaging of the three-dimensional distribution of hydrogen atoms in actual devices at a sub-nanometer scale.

Hydrogen bonding and thermomechanical properties of model polydimethylsiloxane based poly(urethane-urea) copolymers: Effect of hard segment content

Abstract A series of segmented polydimethylsiloxane based poly(urethane-urea) copolymers (PDMSPU) of varied hard segment contents were prepared by moisture curing prepolymers of isophorone diisocyanate capped polydimethylsiloxane. Quantitative analysis of hydrogen bonding characteristics of the segmented copolymers was conducted by using Fourier transform infrared spectroscopy (FTIR). The carbonyl stretching bands were deconvoluted into components corresponding to different free and hydrogen bonded groups. The studies revealed the presence of unusually ordered urea domains in the segmented copolymers evidenced from peaks at 1622–1632 cm −1 , despite hitherto reported constraints to such ordered domain formation in these copolymers. This in turn manifested in the appearance of crystalline peaks in the wide angle X-ray diffraction (WAXD) profiles of the copolymers, which could also be directly visualized by scanning electron microscopy (SEM) and polarized optical microscopy (POM) studies. The effect of these morphological features on the thermomechanical properties of the segmented copolymers was investigated by dynamic mechanical analysis, tensile testing and hardness measurements. A good correlation between the hydrogen bonding characteristics and thermomechanical properties of the copolymers could be established.

<i>In Situ</i> Structure-Sensitive Studies of Metal-Hydrogen Interactions by Scanning Kelvin Probe

Effect of hydrogen on metals is a complex phenomenon. The objective of this paper was to outline the recent application of scanning Kelvin probe (SKP) for a deeper understanding of nature and properties of metal-hydride system. SKP belongs to the family of scanning probe electrochemistry techniques (SPETs) that are currently used and developed. Different applications of SKP technique for hydrogen detection in metals, hydrogen permeation through metals with high local resolution, and quantitative analysis of hydrogen in materials, were presented. The emphasis in this work was on presenting specific applications of SKP rather than extensive reviews; details of how and why this technique is useful in research area was given.

Infrared spectroscopy of some carbon-based materials relevant in combustion: Qualitative and quantitative analysis of hydrogen

A detailed procedure for the quantitative analysis of aromatic and aliphatic hydrogen based on infrared spectroscopy was set up and implemented on some carbon-based materials produced from organic precursors (naphthalene pitch) and/or relevant in combustion field (asphaltenes, carbon particulate matter, carbon black), spanning in the H/C atomic ratio range from 0.1 to 1. The quantitative FT-IR analysis involved the spectral deconvolution in the CH vibrations regions and the calibration factors of diverse standard species having spectral characteristics suitable for the detailed peak-to-peak analysis of the CH stretching (3100–2800cm−1) and aromatic CH bending (900–700cm−1) regions. The good agreement between the H/C atomic ratio obtained by quantitative FT-IR analysis and elemental analysis showed a reasonable reliability of the procedure. The major value of the developed FT-IR quantitative technique relies also on the capacity of discriminating between the different kinds of aliphatic and aromatic hydrogen. The quantitative and detailed analysis of hydrogen in form of CH3, CH2 and CH groups and in form of solo, duo and trio/quatro aromatic hydrogens showed to be useful also for inferring the structure of the aromatic moieties constituting the CC backbone of carbon materials.

Quantitative analysis of hydrogen bonding in electrospun fibers of poly(4-vinyl pyridine)/(4,4′-biphenol) complexes by ATR using liquid blends as models

To understand the characteristics of electrospun fibers of poly(4-vinyl pyridine) (P4VP) that are potentially crosslinked by hydrogen-bonding when blended with small molecules like 4,4′-biphenol (BiOH), it is necessary to determine the proportion of hydrogen-bonded pyridine rings (fb) and to contrast it with FOH, the mole percent of OH groups available for interacting with the pyridine rings. While this can be done by Fourier transform infrared spectroscopy (FTIR), two practical difficulties must be overcome. First, the correct intensities of the overlapped bands of free and hydrogen-bonded pyridine must be obtained, which is possible using the second derivative spectra. Second, the band absorption coefficient ratio (a) of the pair of bands must be known. In the P4VP/BiOH system, only the pair of free and hydrogen-bonded pyridine ring bands at 993 and 1007cm−1 can be used for quantitative analysis. We determined, by analysis of liquid blends of BiOH as well as phenol with a model compound, 4-ethylpyridine (EtPy), using the attenuated total reflection mode (ATR), that a=0.40. This led to values of fb=FOH, indicative of full complexation of the OH groups to pyridine, in the EtPy/BiOH liquid blends up to the BiOH solubility limit in EtPy (FOH=60%) and in the EtPy/phenol blends up to FOH=100%. In the electrospun P4VP/BiOH fibers prepared from solutions with FOH up to about 120%, fb averages 0.76FOH, and full complexation of the pyridine groups is achieved only at about FOH=160%. In both P4VP/BiOH and EtPy/BiOH, the complexation occurs between one pyridine ring and one hydroxyl group. This work thus shows a new method to quantify the relative number of hydrogen-bonded pyridine rings in P4VP; it is expected to be applicable to other polymer-small molecule and polymer-polymer blends having suitable liquid models.

Quantitative analysis of hydrogen in amorphous silicon using Raman scattering spectroscopy

Hydrogenated amorphous silicon (a‐Si:H) films were studied using infrared and Raman spectroscopy. We have experimentally found that ratios of Raman scattering cross‐sections for Si–H to Si–Si bonds and for Si–H2 to Si–Si bonds are equal to 0.65 ± 0.07 and 0.25 ± 0.03, respectively. It allows to measure the concentration of hydrogen in a‐Si:H films. The developed approach can be applied for in situ control of hydrogen in a‐Si:H films and also suitable for thin a‐Si:H films on substrates that are opaque in infrared spectral region. Copyright © 2013 John Wiley & Sons, Ltd.

Quantitative hydrogen analysis in minerals based on a semi-empirical approach

Hydrogen normally occurs as hydroxyl ions related to defects at specific crystallographic sites in the structures, and is normally characterized by infrared spectroscopy (FTIR). For quantification purposes the FTIR technique has proven to be less precise since calibrations against independent methods are needed. Hydrogen analysis by the NMP technique can solve many of the problems, due to the low detection limit, high lateral resolution, insignificant matrix effects and possibility to discriminate surface-adsorbed water. The technique has been shown to work both on thin samples and on thicker geological samples.To avoid disturbance from surface contamination the hydrogen is analyzed inside semi-thick geological samples. The technique used is an elastic recoil technique where both the incident projectile (proton) and the recoiled hydrogen are detected in coincidence in a segmented detector. Both the traditional annular system with the detector divided in two halves and the new double-sided silicon strip detector (DSSSD) has been used.In this work we present an upgraded version of the technique, studying two sets of mineral standards combined with pre-sample charge normalization. To improve the processing time of data we suggest a very simple semi-empirical approach to be used for data evaluation. The advantages and drawbacks with the approach are discussed and a possible extension of the model is suggested.

Solid state electrochemical hydrogen sensor for aluminium and aluminium alloy melts

The presence of dissolved hydrogen in molten aluminium and its alloys has a critical impact on the quality of cast aluminium components. The quantitative analysis of hydrogen in these melts is therefore of major importance in the aluminium industry. Research work conducted at the University of Cambridge and subsequent development work performed in conjunction with an industrial partner, have resulted in a novel, and now commercialised, electrochemical hydrogen sensor for aluminium melts. The sensor operates in the potentiostatic mode and relies on a proton-conducting solid electrolyte and a metal/hydrogen-based solid reference electrode. This article summarises the main steps of the underlying research and development programme, covering the actual gas sensor, test measurements in gas phases under laboratory conditions, the probe for molten metal application, and test measurements in aluminium melts under industrial conditions.

ChemInform Abstract: Analyzing Hydrogen in Metals: Surface Techniques

AbstractReview: 50 refs.

Imaging of an operating LaNi 4.8Al 0.2–based hydrogen storage container

In this paper the phenomena occurring inside of a hydrogen storage container (filled with LaNi 4.8Al 0.2 active material), in operation, are unveiled by means of high-resolution neutron radiography and tomography. Although the metallic hydride-based storage systems are commonly used and commercially available, the processes occurring inside of such devices have been derived rather on the knowledge of several external parameters (changes of H 2 pressure or the container’s temperature) characterising the whole container than on a direct experimental evidence of the container’s interior. The results of neutron imaging experiments reported here show the possibility of qualitative as well as quantitative analysis of hydrogen absorption/desorption kinetics with spatial resolution of 70 μm.