Saturated Hydrogen Research Articles

OXIDATIVE MODIFICATION OF PROTEINS IN COLORECTAL CANCER UNDER THE INFLUENCE OF 5-FLUOROURACIL AND MOLECULAR HYDROGEN

The aim of the study – to investigate the effect of water saturated with molecular hydrogenand 5-fluorouracil on the content of carbonyl groups of oxidatively modified proteins inthe blood serum of white rats with colorectal cancer.Material and Methods. The experiments were conducted on 50 male Wistar rats. Theanimals were modeled with colorectal cancer (CRC) by subcutaneous injection of1,2-dimethylhydrazine (DMH) at a dose of 7.2 mg/kg body weight once a week for 30weeks. 5-Fluorouracil was administered intraperitoneally for 4 days at 12 mg/kg andfor another 4 days every other day at 6 mg/kg. Animals consumed water enriched withmolecular hydrogen at a concentration of 0.6 ppm ad libitum. Rats were euthanizedunder thiopental anesthesia. Blood serum was used for the study, in which the content ofcarbonyl groups was determined by the colorimetric method. Statistical data processingwas performed using the SPSS-22 software package.Results. It was found that the modeling of colorectal cancer led to a 1.77-fold increase inthe content of carbonyl groups in the blood serum of rats compared to intact animals. Thecontent of carbonyl groups in the blood serum of rats with CRC treated with chemotherapyby administration of 5-fluorouracil increased 1.93 times compared to the intact groupand 1.1 times compared to animals with CRC. Consumption of water saturated withmolecular hydrogen 30 days after modeling CRC and administration of 5-fluorouracilto white rats led to a 1.18-fold decrease in the content of carbonyl groups in their bloodserum compared to animals with CRC who were administered 5-fluorouracil but did notconsume water saturated with molecular hydrogen.Conclusions. The use of molecular hydrogen saturated water is an effective methodof reducing oxidative modification of proteins in rats with colorectal cancer under5-fluorouracil chemotherapy.

Hydrogen adsorption, migration and desorption on amorphous carbon: A DFT and AIMD study

Physisorption is the general dominating adsorption mode on pure carbonaceous materials. In this study, we examined if chemisorbed hydrogen can be accomplished without incorporating metals on carbon surfaces. We constructed two 100-atom amorphous carbon (a-C) models with different microenvironments (42 % 2-fold, 52 % 3-fold, and 6 % 4-fold coordinated carbon atoms and 18 % 2-fold and 82 % 3-fold, respectively) using ab initio molecular dynamics (AIMD) simulations to mimic activated carbon samples in reality. The structural, energetic, electronic structure and kinetic properties of hydrogen adsorption, migration, and desorption on the a-C surfaces were analyzed using density functional theory (DFT) and AIMD calculations, which showed that: (1) hydrogen molecules could spontaneously dissociate on the convex side of 2-fold coordinated carbon atoms. Physisorption of hydrogen molecules mainly took place on 3-fold coordinated carbon atoms. (2) Regarding the multiple hydrogen adsorption, the entire a-C model could uptake around 156 hydrogen atoms with the adsorption energy per hydrogen atom about −0.70 to −0.60 eV at high hydrogen pressure. In addition, we found that the average individual adsorption energy of a single hydrogen atom on different carbon atoms could be used as a quick prediction for the saturated hydrogen adsorption energy. (3) The migration barrier of a hydrogen atom between two adjacent carbon atoms was about 2 eV at both low and high hydrogen coverage, indicating that hydrogen mobility on this designed a-C model was low. The desorption of a hydrogen molecule can take place at 300 K using AIMD calculation, but not for atomic hydrogen desorption. In this work, we demonstrated that hydrogen chemisorption could take place on this designed a-C without the decoration of metal particles to enhance hydrogen adsorption amounts. The materials design to balance hydrogen chemisorption, migration, and desorption shall be considered in the future.

Porous Silicone Rubber Composite Supported 1,4-Diphenylethynyl Benzene for Hydrogen Absorption with Pd/C Catalyst.

Hydrogen is a dangerous gas as it reacts very easily with oxygen and may explode; therefore, the accumulation of hydrogen in confined spaces is a safety hazard. Composites consisting of unsaturated polymers and catalysts are a common getter, where the commonly used polymer is 1,4- diphenylethynyl benzene (DEB). Silicone rubber (SR) is a good carrier for hydrogen-absorbing materials due to its excellent chemical stability and gas permeability. In this work, polysiloxane, water, and a emulsifier are ultrasonically injected into a uniform emulsion, and the hydrogen getter DEB-Pd/C (Palladium on carbon) is then added. Under the catalysis of platinum (Pt), the cross-linking agent undergoes a hydrosilylation reaction to cross-link polysiloxane in emulsion to form silicone rubber. Then, the water was removed by freeze-drying, and the loss of water constructed a porous frame structure for silicone rubber, thus obtaining porous silicone rubber. The difference in hydrogen absorption performance between porous silicone rubber and ordinary silicone rubber was compared. It was found that, with the increase in water in the emulsion, the porous frame of silicone rubber was gradually improved, and the hydrogen absorption performance was improved by 243.4% at the highest, almost reaching the theoretical saturated hydrogen absorption capacity. Porous silicone rubber was prepared by emulsion mixing, which provided a new idea for further improving the hydrogen absorption performance of silicone rubber.

Elucidating the atomic stacking structure of nickel phyllosilicate catalysts and their consequences on efficient hydrogenation of 1,4-butynediol to 1,4-butanediol

The hydrogenation of 1,4-butynediol (BYD) to 1,4-butanediol (BDO) plays a pivotal role in the production of biodegradable plastics, including PBAT and PBS. Herein, we prepared a range of nickel phyllosilicate catalysts with diverse atomic stacking configurations for the direct synthesis of BDO via BYD hydrogenation. In comparison to conventional supported Ni catalysts, the metal sites derived from nickel phyllosilicate demonstrated remarkable hydrogenation activity for the conversion of CC-C-OH alkynol to C-C-C-OH alkanol. Both the physical structures and -importantly- chemical properties of these catalysts were crucial for product selectivity and yield; and a BDO yield of 93.4 % with complete conversion of BYD was achieved at 50 °C and 1 MPa H2 over the Niphy@SiO2-UDP catalyst with a pure 1:1 Ni phyllosilicate structure. Kinetic experiments and theoretical calculations confirmed that the initial hydrogenation of BYD to 1,4-butenediol (BED) was the rate-determining step for the saturated hydrogenation to BDO. The metallic Nisite is responsible for the dissociation of hydrogen, while due to the enhanced synergism derived from the 1:1 atomic stacking phyllosilicate structure, a type of cooperated Ni-Niδ+-acid sites can stabilize the CC electron cloud over the carbon chain of BED intermediate, hence benefiting its further hydrogenation, and suppressing its isomerization to undesired aldol condensation byproduct. Our findings provide valuable insights into the atomic stacking structures of metal phyllosilicate catalysts, revealing the micro-environment of chemical properties and interactions that govern the state/activity of Ni species, which is helpful for the rational design of other hydrogenation catalysts with enhanced performance.

Research on the hydrogenation behavior of magnetocaloric La0.8Ce0.2Fe11.51Mn0.19Si1.3 hot-pressed plates

The fabrication of La(Fe, Si)13Hy plates is very challenging owing to the poor mechanical stability. In this work, La(Fe, Si)13 plates synthesized by hot-pressing remain mechanically robust after optimizing the hydrogenation process. The hydrogenation behavior was investigated through characterizing the phase structures and magnetocaloric effects of La0.8Ce0.2Fe11.51Mn0.19Si1.3 hydride plates. The saturated hydrogenation plates exhibit the large magnetic entropy change (12.98 J/kg·K), excellent mechanical properties (bending strength ∼ 213 MPa) and good stability under the conditions of the hydrogenating temperature of 593 K, the pressure of 0.13 MPa for 210 min.

Reaction modelling of hydrogen evolution on nickel phosphide catalysts: density functional investigation.

Nickel phosphides (NixPy), particularly Ni2P, are promising catalysts for the acidic hydrogen evolution reaction (HER). Using density functional theory (DFT), we model HER at the potential of zero charge (PZC), incorporating solvation effects via an explicit water cluster and implicit surrounding solvent. Comparing the Volmer, Tafel, and Heyrovsky steps under saturated hydrogen coverage on Ni2P(0001) terminations, we find that the Ni3P2 (pristine) surface termination prefers the Volmer-Volmer-Tafel (VVT) pathway with activation energy (Ea) of 0.57 eV. Conversely, the Ni3P2 + 4P (reconstructed) surface favors the Volmer-Heyrovsky (VH) pathway with Ea = 0.60 eV. For the pristine surface termination, the differential gas-phase hydrogen adsorption free energies (ΔGdiff) correlate with the Volmer and Tafel step reaction energies, and a linear Bell-Evans-Polanyi relationship for the calculated activation and reaction energies validates the usefulness of the ΔGdiff descriptor for the Volmer step under PZC conditions. Nickel atoms play a crucial role in H2 production on both pristine and reconstructed surfaces, suggesting that modifications of the Ni sites can be used for catalyst design. Our findings highlight the importance of considering surface reconstruction and solvation effects on the HER catalytic performance.

The synergistic effect of Ni and C14 Laves phase on the hydrogen storage properties of TiVZrNbNi high entropy hydrogen storage alloy

As a hydrogen storage alloy, the body-centered cubic (BCC) structure has been well studied due to its large hydrogen storage capacity. On this basis, the introduction of catalytic elements and an appropriate amount of C14 Laves phase can further improve the comprehensive hydrogen storage properties of hydrogen storage alloys. Based on this theory, (Ti32.5V27.5Zr7.5Nb32.5) 1-xNix (x = 0.03, 0.06, 0.09) high entropy hydrogen storage alloys with an appropriate amount of catalytic element Ni are prepared in this study. The raise in Ni content is accompanied by grain refinement of the dendritic structure, an increase in the number of grains and grain boundaries, and a gradual increase in the proportion of C14 Laves phase. The introduction of catalytic element Ni reduces the dissociation energy of hydrogen molecules. The increasing grain and grain boundaries increase more hydrogen absorption sites with lower activation energy. The diffusion channel provided by the appropriate amount of C14 Laves phase makes it easier for hydrogen atoms to diffuse into the main phase BCC phase with strong hydrogen absorption capacity, and the hydrogen atoms are trapped by vacancy defects with large hydrogen binding energy. The synergistic effect of the three factors ensures the improvement of hydrogen absorption performance of high entropy hydrogen storage alloys. (Ti32.5V27.5Zr7.5Nb32.5) 0.94Ni0.09 high entropy hydrogen storage alloy achieves excellent saturated hydrogen storage capacity of 2.78 wt % and 2.99 wt % at room temperature and 150 °C under 3 MPa hydrogen pressure, respectively. In addition, the introduction of Ni element reduces the thermal stability of metal hydrides, thereby improving the dehydrogenation performance of high entropy hydrogen storage alloys. The reversible phase transition occurs during the whole hydrogen absorption and desorption cycle.

Very High Cycle Fatigue Properties and Damage Evolution in Al-Si Cast Alloys

Abstract The steady progress in electro mobility increases the demand for lightweight space frame and engine solutions. Advanced aluminum-silicon cast alloys with additions of magnesium, copper, or both for precipitation hardening are promising candidates for lightweight structures because of their high strength-to-weight ratio. For a reliable design, the fatigue performance in the very high cycle fatigue (VHCF) regime must be understood. Therefore, this study deals with the influence of frequency on VHCF properties as well as fatigue damage evolution in AlSi7Mg and AlSi10Mg sand-cast alloys. The VHCF tests were performed using a resonant (70 Hz), a high-frequency resonant (1 kHz), and an ultrasonic (20 kHz) fatigue testing system. Thereby, a significant frequency effect could be determined that resulted in an increased fatigue lifetime by 1 decade at 1 kHz and by 2 decades at 20 kHz, whereas no significant change in fatigue limit could be determined. Moreover, the fatigue crack initiation mechanisms change from surface crack initiation at 70 Hz and 1 kHz to volume crack initiation at 20 kHz. Using the defect-based Murakami approach, including a lightweight extension of Noguchi, a defect-induced (size, location) frequency effect could be excluded. Based on damage monitoring, the effect could be related to the crack propagation phase, which is accelerated at low frequencies (<100 Hz) because of a humidity reaction with the fatigue crack surface and the formation of atomic hydrogen resulting in a saturated hydrogen embrittlement per cycle. At high frequencies of 1 kHz and 20 kHz, no saturated hydrogen embrittlement per cycle can be reached.

Microstructure and kinetics/thermodynamics of environmentally friendly and recyclable grain regulated Pr-Mg-Ni-based hydrogen storage alloys

The high-energy mechanical milling procedure was used to manufacture the as-milled Pr5Mg85Ni10 alloys of 5 h, 10 h, 20 h, and 30 h respectively. We have been successful in obtaining a variety of nanocrystalline and amorphous alloys with varying amounts of each. The primary phase in the interior structure of the alloys is still Mg2Ni and Mg, which corresponds to the second phase PrMg12. The products of saturated hydrogen absorption include MgH2, Mg2NiH4, and PrH2.93, while the products of complete hydrogen release include Mg, Mg2Ni, and PrH2. According to the findings, the amount of time spent ball-milling the alloys is the primary component that determines how well they function in terms of the dynamic performance of hydrogen absorption and desorption. The dynamic performance of the alloy in terms of hydrogen absorption and desorption is enhanced with the increasing time spent ball-milling the material. In the same vein, the alloy that has been milled for ten hours has the most desirable thermodynamic characteristics.

High-performance LaFe11.6Si1.4Hy/Al composites for magnetic refrigeration: A good combination of magnetocaloric effect, mechanical properties, and thermal conductivity

Bulk LaFe11.6Si1.4Hy/Al composites with the saturated hydrogen content were prepared by hot pressing and subsequent hydrogenation. Al particles were dramatically deformed when pressed at 773 K, and a reaction of La(Fe,Si)13 and Al phases took place at 873 K. The reinforced skeleton structure consisting of malleable Al phases in the composites allows brittle La(Fe,Si)13Hy particles to be well bonded after hydrogen absorption. As a result, these LaFe11.6Si1.4Hy/Al hydrides show a good comprehensive performance for magnetic refrigeration, i.e., large entropy changes of 9.8–12.5 J/kg K under 2 T, large adiabatic temperature changes of 3.36–3.97 K under 1.9 T, high thermal conductivity of 11.4–45.6 W/m K, and high bending strength of 16.8–48.2 MPa. Particularly, the 20 wt% Al composite possesses a compressive strength of 122 MPa and plastic deformation of 4.6 %.

TiO2@C catalyzed hydrogen storage performance of Mg-Ni-Y alloy with LPSO and ternary eutectic structure

A designed Mg88.7Ni6.3Y5 hydrogen storage alloy containing 14H type LPSO (long-period stacking ordered) and ternary eutectic structure was prepared by regulating the alloy composition and casting. The hydrogen storage performance of the alloy was improved by adding nano-flower-like TiO2@C catalyst. The decomposition of the LPSO structure during hydrogenation led to the formation of plenty of nanocrystals which provided abundant interphase boundaries and activation sites. The nanoscale TiO2@C catalyst was uniformly dispersed on the surface of alloy particles, and the "hydrogen overflow'' effect of TiO2@C accelerated the dissociation and diffusion of hydrogen on the surface of the alloy particles. As a result, the in-situ endogenous nanocrystals of the LPSO structure decomposition and the externally added flower-like TiO2@C catalyst uniformly dispersed on the surface of the nanoparticles played a synergistic catalytic role in improving the hydrogen storage performance of the Mg-based alloy. With the addition of the TiO2@C catalyst, the beginning hydrogen desorption temperature was reduced to 200 °C. Furthermore, the saturated hydrogen absorption capacity of the sample was 5.32 wt.%, and it reached 4.25 wt.% H2 in 1 min at 200 °C and 30 bar.

A New Approach for Enhancing Oil and Gas Recovery of the Hydrocarbon Fields with Low Permeability Reservoirs

A universal and multifunctional method for developing problematic oil and gas fields with low-permeability reservoirs is presented in this paper. The method is based on maintaining reservoir pressure and identifying the hydrogen formation mechanism. According to the analysis of previous laboratory experiments, the article summarizes the results of a computer simulation of a method for developing oil and gas fields with low permeable reservoirs using the commercial software product tNavigator from Rock Flow Dynamics. The proposed method results in multiple times more oil production per each studied well than its production using the depletion mode. Using CO2 in this manner results in additional, useful utilization, and laboratory experiments have indicated that saturated, unsaturated, and aromatic hydrogen are produced as by-products of CO2 injection. Moreover, the proposed method offers similar technological and technical solutions as those that have long been used in the oil and gas industry

Improving hydrogen induced cracking resistance of high strength acid-resistant submarine pipeline steels via trace-Mg treatment

Hydrogen induced cracking (HIC) is one of the biggest service risks faced by high-strength acid-resistant submarine pipeline steel. In this work, we reported a low-carbon, low-cost and high-efficient method for remarkably improving HIC resistance of the high-strength acid-resistant submarine pipeline steels by trace-Mg treatment. The results showed that the non-metallic inclusions steels were obviously refined, softened, spheroidized and dispersed by trace-Mg treatment, the modified “core-shell” or like “core-shell” structure inclusions had a larger critical size for HIC initiation and a higher saturated hydrogen concentration, and then effectively trapping more hydrogen, dispersing hydrogen pressure and reducing the diffused hydrogen content, thus effectively improving the HIC resistance. With the further increasing of Mg contents, the inclusion modification would be weakened, the hydrogen trapping efficiency decreased, and the HIC susceptibility of the tested steel increased again. In the research range, the tested steels treated with 4 ppm Mg present the lowest HIC susceptibility.

Development of (Ti–Zr)1.02(Cr–Mn–Fe)2-Based Alloys toward Excellent Hydrogen Compression Performance in Water-Bath Environments

Three series of alloys, Ti0.92Zr0.10Cr1.7–xMn0.3Fex (x = 0.2–0.4), Ti0.92Zr0.10Cr1.6–yMnyFe0.4 (y = 0.1–0.7), and Ti0.92+zZr0.10–zCr1.3Mn0.3Fe0.4 (z = 0, 0.015, 0.04), were prepared by induction levitation melting for a metal hydride hydrogen compressor from 8 to 20 MPa at water-bath temperature, with investigation on their crystal structural characteristics and hydrogen storage properties. The results show that a single C14-Laves phase with homogeneous element distribution exists in all of the alloys. The hydrogen ab-/desorption plateau of the alloys is increased as the Fe, Mn, or Ti content increases due to decrement of the interstitial site radius originated from the respective atomic size. The hydrogen storage capacity of the alloys also correlates negatively with the hydrogen affinity of interstitial sites due to the influence of the element electronegativity. In a comprehensive consideration of the hydrogen storage performance for application, the Ti0.935Zr0.085Cr1.3Mn0.3Fe0.4 alloy shows saturated hydrogenation under 8 MPa at 293 K and dehydrogenation around 24.91 MPa pressure at 363 K with a hydrogen capacity of 1.74 wt %, as well as excellent cycling performance and mere hysteresis. The Ti0.92Zr0.10Cr1.0Mn0.6Fe0.4 alloy is another promising candidate with a remarkable hydrogen capacity of 1.86 wt % at 283 K and a dehydrogenation pressure of 27.94 MPa at 363 K, together with a satisfactory cycling durability. This study can guide the compositional design of AB2-type hydrogen storage alloys for hydrogen compression application.

Desorption of Ammonia Adsorbed on Prussian Blue Analogs by Washing with Saturated Ammonium Hydrogen Carbonate Solution

Prussian blue analogs (PBAs) have been reported as promising ammonia (NH3) adsorbents with a high capacity compared to activated carbon, zeolite, and ion exchange resins. The adsorbed NH3 was desorbed by heating and washing with water or acid. Recently, we demonstrated that desorption was also possible by washing with a saturated ammonium hydrogen carbonate solution (sat. NH4HCO3aq) and recovered NH3 as an NH4HCO3 solid by introducing CO2 into the washing liquid after desorption. However, this has only been proven for copper ferrocyanide and the relationship between the adsorption/desorption behavior and metal ions in PBAs has not been identified. In this study, we investigated the adsorption/desorption behavior of PBAs that are complexes of first row transition metals with hexacyanometalate anions. Six types of PBAs were tested in this study and copper ferricyanide exhibited the highest desorption/adsorption ratio. X-ray diffraction results revealed high structural stability for cobalt hexacyanocobaltate (CoHCC) and nickel ferricyanide (NiHCF). The Fourier transform infrared spectroscopy results showed that the NH3 adsorbed on the vacancy sites tended to desorb compared to the NH3 adsorbed on the interstitial sites as ammonium ions. Interestingly, the desorption/adsorption ratio exhibited the Irving-Williams order.

Hydrogen storage characteristics of Ti1.04Fe0.7Ni0.1Zr0.1Mn0.1Pr0.06 alloy treated by ball milling

In order to enhance the hydrogen storage performances of TiFe alloy, the Ti1.04Fe0.7Ni0.1Zr0.1Mn0.1Pr0.06 alloy was prepared through using transition metals (Ni, Mn, Zr) partially substitute Fe and rare earth Pr partially substitute Ti. The microstructure of the alloy was further adjusted by ball milling for different time. The master alloy contained TiFe, Ti2Fe and Pr phases. Ball milling treatment led to the reduction of the particle size and grain size. The master alloy (M-0 sample) and the alloys with short-time ball milling treatment (M-0.5 and M-1 samples) absorbed hydrogen immediately at the first hydrogenation cycle at 423 K and 3 MPa H2, while the alloys with long-time ball milling treatment (M-3 and M-5 samples) showed an incubation time. The M-0.5 sample not only presented the optimum activation property, but also showed the most outstanding hydriding/dehydriding kinetics and capacity. It achieved the saturated hydrogenation state within 2158 s. The hydrogenation capacity was 1.471, 1.626, 1.547, 1.485 and 1.417 wt% for the M-0, M-0.5, M-1, M-3 and M-5 samples at 313 K and 3 MPa H2, respectively. In addition, ball milling treatment caused the decrease of cell volume of TiFe phase in the samples, which reduced the thermodynamic stability of the hydrides.

Selective hydrogenation of 2-methylnaphthalene by heterostructured Ni-NiO-based catalysts for 6-methyl-1,2,3,4-tetrahydronaphthalene

As an important intermediate of organic chemical industry, 2-methylnaphthalene (2-MN) has the application value in the field of medicine and material research. Up to date, the existing researches are aimed at 2-methylnaphthalene saturated hydrogenation and hydrocracking for high value products such as cycloalkanes and BTXs. A series of Ni-based (20 wt.%) catalysts were prepared with different reduction temperatures for the hydrogenation of 2-methylnaphthalene to 6-methyl-1,2,3,4-tetrahydronaphthalene (6-MT) in this study. The results showed that by using NiO/Al2O3-370R, 90.8% conversion of 2-MN and 59.7% yield of desired product (6-MT) can be achieved with optimum reaction conditions of 4 MPa & 340°C, 8 h. Multiple studies including catalyst characterizations, reaction kinetics and density functional theory (DFT) calculation indicates that symbiotic effect of heterostructured Ni-NiO over γ-Al2O3 mainly corresponding to the desired catalytic performance. This study gains fundamental understanding in the effects of valence of Ni-based catalysts in catalytic hydrogenation.

Hubble Space Telescope STIS Spectroscopy of Nova T Aurigae 1891

T Aurigae is an eclipsing old nova that exploded in 1891. At a Gaia EDR3 distance of 815–871 pc, it is a relatively nearby old nova. Through ultraviolet spectral modeling and using the new precise Gaia distance, we find that the HST/STIS spectrum of T Aurigae is consistent with an accretion disk with a mass-transfer rate of the order of 10−8 M ⊙ yr−1, for a white-dwarf mass of M wd ≈ 0.7 ± 0.2M ⊙, an inclination of i ∼ 60°, and a Gaia distance of of pc. The sharp absorption lines of metals cannot form in the disk and are likely forming in material above the disk (e.g., due stream disk overflow), in circumbinary material, and/or in material associated with the ejected shell from the 1891 nova explosion. The saturated hydrogen Lyα absorption feature is attributed to a large interstellar-medium hydrogen-column density of the order of 1021cm−2 toward T Aur, as corroborated by the value of its reddening E(B − V) = 0.42 ± 0.08.

Growth of calcium carbonate crystal on various substrates from a saturated calcium carbonate solution utilizing difference in solubility

Crystalline calcium carbonate was deposited on various substrates (substrate temperature of 80 °C) from a saturated calcium hydrogen carbonate solution (solution temperature of 10 °C). A single aragonite phase deposited on the Al substrate, whereas a mixed phase of aragonite and calcite grew on the soda lime glass, borosilicate glass, silica glass, and polycarbonate substrates. With increasing deposition time, the crystal size and the proportion of calcite on the soda lime silicate glass substrate increased. Furthermore, calcite crystals were preferentially deposited on an Al substrate with a thin film of Au as a buffer layer (Au/Al substrate).

Dynamically Staged Phase Transformation Mechanism of Co-Containing Rare Earth-Based Metal Hydrides with Unexpected Hysteresis Amelioration

Solid hydrogen storage and supply systems with high density in a hydrogen refueling station are the critical factor to realize large-scale application of hydrogen energy, and one of the biggest challenges is how to ameliorate the extremely large pressure hysteresis of Ce-rich rare-earth-based metal hydrides. In this work, two series of La–Ce–Ca–Ni–Co alloys with single CaCu5-type structure and uniformly distributed elements were prepared via induction levitation melting. With increasing Co content in La0.3Ce0.5Ca0.2Ni5–xCox (x = 0, 0.5, 1.0, 1.5) alloys, a staged phase transformation occurs, contributing to a significant improvement in the pressure hysteresis without the monotonical sacrifice of dehydrogenation equilibrium pressure. An equilibrium-state thermal analysis method (ETA) is proposed and well verifies the thermodynamical phase transformation processes. Further first-principles calculations indicate that the enhanced charge synergy and increased charge transfer drive the conversion of staged phase transformation from dynamic to thermodynamically stable pathways. Thus, “dynamically staged phase transformation”, nominated as the dynamic realization of thermodynamic staged phase transformation, is more constructive for practical use. Consequently, the optimal composition of La0.25Ce0.55Ca0.2Ni4.5Co0.5 was developed with a saturated hydrogen storage capacity of 1.52 wt %, dehydrogenation equilibrium pressure of 10.68 MPa at 90 °C, and satisfactory cycling durability. The ETA method and composition design concept proposed in this work pave a convenient avenue for wider exploration of high-pressure hydrogen storage alloys.