Hydrogen dispersion and concentration distribution characteristic from a hydrogen-powered bus release in tunnel

Effect of hydrogen concentration on neutron moderation of hydrides at 900 K

Experimental results are compiled to show apparent hysteresis seen in hydride thermal precipitation–dissolution cycling in zirconium alloys using X-ray diffraction, dynamic elastic modulus techniques, and differential scanning calorimetry (DSC). Gibbs’ phase rule is used to justify a description of a stable hydride in the H-Zr system in terms of a control volume with a hydride at its core, surrounded by a stress gradient that produces a stabilizing gradient of hydrogen in the solution. The conditions for a stable hydride are derived when the flux of hydrogen in solid solution is zero. DSC heat flow curves are analyzed with a thermodynamic model that predicts concentrations of hydrogen in a solution during temperature cycling and a description of experimental results that show how concentrations evolve at a constant temperature to the same final state when cycling is paused, from which hysteresis is deemed an illusion. The control volume is supported by previous energy calculations, performed with density functional theory. Implications of replacing the order parameter for phase field methods with the gradient of the yield stress are discussed. A practical method for forming a stable hydride is presented.

Abstract Hydrogen embrittlement (HE) is a widely recognised phenomenon that can expressively impact high-strength materials. In particular, high-strength steels are susceptible to delayed fracture, a form of hydrogen embrittlement that may occur during vehicle service. HE can trigger fracture, accelerate subcritical crack growth, and result in catastrophic failure, ultimately reducing mechanical properties like strength, toughness, and ductility. Hydrogen can penetrate materials either through electrochemical reactions or exposure to high-pressure hydrogen environments. To evaluate its impact on mechanical properties and measure the absorbed hydrogen content, several techniques are employed, such as Slow Strain Rate Testing (SSRT), Linearly Increasing Stress Testing (LIST), and Thermal Desorption Spectroscopy (TDS). In automotive steels, a typical amount of hydrogen can be found in the range of 1 to 5 ppm (parts per million) by weight, but this can vary depending on the type of steel and its processing. The extent of mechanical degradation is not a standard metric but can evident as a significant loss of ductility, such as a loss in ductility by 30% or more which can depend on many factors like stress, hydrogen concentration, and environmental conditions. Several mechanisms responsible for HE is also explored. This paper summarizes phenomenon of HE, HE mechanisms and prevention methods which retard the process of hydrogen diffusion, subcritical crack growth, techniques to quantify absorbed hydrogen.

Willows (genus Salix) are versatile plants with applications in construction, medicine, and biomass fuel in North America. Advances in breeding have improved willow clones for higher yields and pest resistance, but the chemical content and distribution across different plant parts remain poorly understood. This study examined the variation in chemical elements (carbon, hydrogen, nitrogen, sulfur, chlorine, and ash) across six willow clones (India, Jorr, Olof, Otisco, Preble, and Tora) and three tissue types (wood, bark, twigs). We also compared freeze-drying and oven-drying methods to assess their impact on chemical content. Freeze-dried samples generally exhibited higher carbon and hydrogen concentrations than oven-dried samples, with statistically significant differences primarily observed for carbon, while nitrogen showed no overall significant difference between drying methods. Chemical composition varied among clones, although no single clone consistently dominated across all chemical parameters. In contrast, pronounced tissue-type differences were observed: bark had higher nitrogen, carbon, sulfur, chlorine, and ash contents, whereas wood exhibited relatively higher hydrogen concentrations, with twigs showing intermediate values. These findings suggest that accounting for tissue-specific chemical differences can improve the selection and utilization of willow biomass and increase the accuracy of ecological assessments, including carbon storage estimates. The findings of this study indicate that oven-drying should remain in use within the bioenergy sector, whereas freeze-drying ought to become the preferred standard for carbon-accounting protocols.

Despite the widespread occurrence of mostly low concentrations of molecular hydrogen (H₂) in nature, the quantity of commercially recoverable natural hydrogen underground remains uncertain. Two production variants are conceptually considered: a self-replenishing system, in which underground generation balances off-take; and accumulation systems, in which H₂ is trapped underground over long periods and is extracted similarly to conventional natural gas deposits. To assess the potential of natural hydrogen, we compiled and harmonised global data on H₂ flow rates, flux rates, and concentrations from various sources like seeps, springs, mines, and wells. Across different geological settings, observed large natural H₂ flow rates typically fall between 10⁵ and 10⁷ cubic meters per year (m³/yr). When comparing these values to the output of producing natural gas wells and economic viability thresholds for modelled H₂ projects, we find that commercially viable rates must be at least an order of magnitude higher (≥ 10⁷–10⁸ m³/yr). Furthermore, sustained production at high hydrogen purity over two to three decades is generally required for commercial success. Based on this analysis, we argue that economically recoverable natural hydrogen from self-replenishing systems is unlikely.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-026-36749-y.

We study hydrogen diffusion in silicon by annealing wafers with hydrogen-rich aluminum oxide layers on one surface and intrinsic PECVD silicon films acting as a hydrogen capture sink on the other surface. The hydrogen concentration in the silicon film is monitored via spectrally resolved sub-bandgap photoluminescence, calibrated by comparison with time-of-flight secondary ion mass spectrometry measurements. This provides a convenient and rapid method for hydrogen concentration measurements. Modeling the kinetics of the increasing hydrogen concentration in the silicon film as hydrogen diffuses through the wafer allows the effective hydrogen diffusivity to be extracted at annealing temperatures of 300–450 °C, a range that is relevant for silicon solar cell technology, but has not often been directly measured. The extracted hydrogen diffusivities in undoped silicon and both moderately and heavily doped n- and p-type silicon are compared with the existing literature reports. The results match very well with the model of Herring et al. for moderately doped n-type and undoped silicon. For heavily doped n-type and p-type silicon with different dopant concentrations, however, we report significantly reduced effective hydrogen diffusivity values. Finally, we present the modeling of hydrogen charge states in differently doped silicon and consider possible explanations for the reduction in effective hydrogen diffusivity.

Trace measurement of pH value is of great significance in modern fields such as industry, agriculture, medicine, environmental science, and bioengineering. Microfluidic chips that combine polydimethylsiloxane (PDMS) with gallium nitride high-electron-mobility transistors (GaN HEMTs) provide an effective method for the trace detection of hydrogen ion concentration in solutions. Based on AlGaN/GaN high-electron-mobility transistors, this study conducts a systematic analysis by comparing sensors packaged with PDMS for devices with a width-to-length ratio (W/L) of 800/400 μm and those with traditional packaging. It is found that the sensor packaged with PDMS has a current sensitivity slightly higher than that of the traditionally packaged sensor, reaching 139.92 μA/pH (134.6 μA/pH for the traditional package), and its voltage sensitivity is also slightly higher than the latter, standing at 49.95 mV/pH (44.77 mV/pH for the traditional package). In addition, on the premise of ensuring sensing performance, detection can be completed with only 5 μL of solution. Therefore, the application of the microfluidic chip system can not only improve the sensitivity and response speed of the sensor but also significantly reduce the experimental cost.

Abstract Hydrogen is seen as a promising energy carrier, as society seeks to achieve net-zero emissions. One approach to integrating hydrogen into energy systems is to blend it with natural gas, which could decrease the quantity of methane, the primary component of natural gas and a potent greenhouse gas, emitted to the atmosphere. Due to hydrogen’s small molecular size and high mobility, there is concern that hydrogen-natural gas blends (hythane) may leak more than pure natural gas. Previous studies indicate that blends up to ~20% hydrogen by volume may be used in existing natural gas infrastructure, but additional studies are needed for higher hydrogen contents. Therefore, we conducted chamber-based methane emission measurements at natural gas distribution infrastructure and end-use piping using hythane of 0% to 40% hydrogen by volume. We found that total methane emissions were 7% to 26% lower for hythane than for natural gas only; however, methane gas loss rates were between 3.5% and 6.5% higher for hythane blends than for natural gas, with higher gas loss rates for increasing hydrogen content. Average in-pipe flow rates increased proportionally with hydrogen content when the pressure of the pipeline was between 1.6 kPa and 16 kPa; however, we did not observe this trend for the higher-pressure pipeline measured (385 kPa). Further, we saw gas loss rates were mildly correlated to average in-pipe flow rates but were not correlated to in-pipe flow turbulence. Our testing shows that total methane leakage can be reduced by hythane blending for up to 40% hydrogen content, with minimal infrastructure upgrades in the short term. However, testing across a wider range of infrastructure and long-term studies are needed to fully evaluate methane leakage during hythane usage in existing infrastructure.

A wide variety of materials and device architectures have been explored for memristor applications targeting neural network simulations, most of which rely on oxide-based structures that exhibit resistive switching driven by oxygen-vacancy-mediated memory effects. In this study, we present a novel approach for modulating resistive and nonvolatile memory behavior in oxide semiconductors through the controlled injection and extraction of hydrogen. The proposed two-terminal device incorporates a hydrogen source layer that facilitates the diffusion of hydrogen ions into the active oxide matrix, where they form hydroxide (OH) bonds and locally modulate the electron concentration. This process induces a stable and reversible memory effect under an applied electric field. Hydrogen exchange predominantly occurs at the interface between the active and insulating layers, with the latter serving as a buffer to maintain an optimal hydrogen concentration. Furthermore, neural network simulations were performed by utilizing the synaptic characteristics controlled via hydrogen modulation, achieving a recognition accuracy of 97.2% on the MNIST data set. The effects of input data resolution and weight quantization on recognition performance were also systematically investigated and discussed.

The study aims to develop a method for obtaining a high-performance catalyst for the synthesis of liquid hydrocarbons using the Fischer–Tropsch method based on ultradisperse cobalt powders obtained by the electric explosion method. To determine the catalytic activity of the obtained catalyst samples, the main process parameters, like temperature in the catalyst bed, the process pressure, the feedstock space velocity, and the ratio of reagents in the synthesis gas, were varied. It has been established that highly dispersed cobalt powder obtained by the electrical explosion method is a fairly active catalyst for the synthesis of liquid hydrocarbons via the Fischer–Tropsch process. It has been established that the overall CO conversion rate in the temperature range from 230 to 330 °C ranges from 25 to 90%. However, the formation of the main byproduct of the synthesis, carbon dioxide, is not observed below 270 °C. It was determined that for the developed catalyst sample, the optimal temperature range is from 230 to 260 °C, in which the yield of by-products of synthesis and gaseous hydrocarbons is quite low—the selectivity for methane does not exceed 20%, with the proportion of C5+ hydrocarbons in the liquid phase at the level of 80%. The CO conversion rate increases proportionally with growing pressure. It has been established that cobalt nanopowder exhibits high catalytic activity in reactions of liquid hydrocarbon formation with low hydrogen content in the initial synthesis gas. This fact allows us to conclude that it has potential for use in processing gases obtained during the pyrolysis of biomass or other non-traditional sources of synthesis gas, characterized by an H2:CO ratio of 1:1 to 1.25:1. Catalysts obtained from ultradisperse cobalt powders were shown to be resistant to rapid deactivation under synthesis conditions at operating temperatures for 30 h. During long-term testing, CO conversion remained at 23.5% at 230 °C for the entire duration of the experiment.

Hydrogen has emerged as a therapeutic agent in inflammatory critical illnesses due to its potential to modulate inflammation and oxidative stress. However, its role in extracorporeal membrane oxygenation (ECMO), a life-saving intervention for severe cardiorespiratory failure associated with pronounced inflammation and oxidative stress, remains largely unexplored. This ex vivo study investigated whether ECMO could serve as an effective vehicle for hydrogen delivery. It also evaluated hydrogen's effects on oxidative stress, inflammation, and coagulation responses arising from the interaction between human blood and non-biological ECMO surfaces. Four healthy male volunteers each provided two blood donations, 6 months apart. We assigned human blood-filled ECMO circuits to two different sweep gas formulations: a CO₂-enriched gas mixture (n = 4) or a mixture of 2% hydrogen in CO₂-enriched gas (n = 4). At T0, stable hydrogen concentrations (9.82 ± 1.97 μmol/L) were achieved and maintained for 6 hours, confirming the reliability of the hydrogen delivery method. Hydrogen exposure significantly reduced collagen (p = 0.01), TRAP-6 (p = 0.04), and ADP-induced (p = 0.04) platelet aggregation and showed a trend toward reduction in oxidative stress markers. In conclusion, this preliminary ex vivo study demonstrates the feasibility of delivering hydrogen gas via the sweep gas of a clinically established ECMO machine and its initial effects on blood, warranting further investigation in larger preclinical animal models.

Abstract In order to improve the safety of vehicle-mounted liquid hydrogen storage and transportation and reveal the leakage and diffusion characteristics of vehicle-mounted liquid hydrogen in open space, a numerical simulation model of liquid hydrogen leakage and diffusion was established. The leakage and diffusion behavior of liquid hydrogen during transportation was studied. The influence of wind speed, leakage rate, leakage time, wind temperature, ground temperature and other factors on the diffusion behavior of hydrogen clouds was analyzed. The results show that the flammable hydrogen cloud formed after the leakage of liquid hydrogen diffuses from the near ground to the distant air, and the volume expands rapidly, resulting in a significant increase in the potential hazard area. The combustible hydrogen cloud has typical radial concentration gradient distribution characteristics, and the hydrogen concentration decreases from the center to the periphery. The spatial diffusion range and volume change are mainly affected by wind speed, leakage rate, and leakage duration, while the influence of wind temperature and ground temperature is relatively limited.

In this study, WSe2, Ag2Se, andWSe2/Ag2Se nanostructured electrodes were synthesizedviaan electrochemical deposition method, and their hydrogen gas sensingperformances were systematically investigated. The synergistic interactionbetween WSe2 nanosheets and Ag2Se nanoparticlessignificantly enhanced charge transport and catalytic activity inthe hybrid electrode. Compared to the pristine WSe2 andAg2Se electrodes, the hybrid electrode exhibited a remarkablyhigher current response of 7.89 mA cm–2 at 5000ppm of H2 and demonstrated stable and reversible sensingbehavior over a wide range of hydrogen concentrations (1000–5000ppm). Analyses of SEM, Raman, and UV–Vis data revealed an increasedsurface area and improved electronic coupling within the hybrid structure.Furthermore, EIS and OCP measurements confirmed accelerated interfacialcharge transfer and superior electrochemical stability. Overall, thisstudy introduces a novel electrochemically synthesized WSe2/Ag2Se hybrid nanostructure exhibiting excellent sensingperformance at low temperatures (25–150 °C) and providesa promising strategy for the development of low-power, highly stablehydrogen gas sensors.

Optimization of oxygen and hydrogen analysis in salts by inert gas fusion.

Development of an optimization genetic algorithm method for estimating municipal solid waste composition.

A microneedle-based miniaturized all-solid-state sensor for in vivo and in situ real-time monitoring of hydrogen ion concentration in tomato stems

Numerical investigation of hydrogen content effect on the combustion characteristics of blended hydrogen–methane bluff-body stabilized swirl flames

Production of second-generation polyhydroxybutyrate from corn hydrolysis residue and biopolymer characterization - A strategy to repurpose agro-wastes.

The article presents the results of an experimental study on the kinetics of cantilever deformation in the α-region of the α-PdHn alloy, conducted during successive hydrogen injections with the same concentration increase and different gas supply rates. It was established that each subsequent hydrogen injection leads to an increase in the time to achieve maximum bending and its duration, which is associated with the accumulation of hydrogen in the crystal lattice and the growth of internal concentration stresses. For the first time, a pronounced plateau effect was experimentally observed after achieving maximum bending, indicating the establishment of thermobaroelastic equilibrium between the processes of hydrogen penetration and the mechanical reaction of the material. Exponential relationships between the bending magnitude and the time to achieve it, as well as logarithmic relationships between the bending and the hydrogen supply rate, were established. The obtained patterns can be used to predict the behavior of palladium alloys in a hydrogen environment and to develop hydrogen concentration sensors.