Hydrogen Research Articles

The JWST/NIRSpec view of the nuclear region in the prototypical merging galaxy NGC 6240

Merger events are thought to be an important phase in the assembly of massive galaxies. At the same time, active galactic nuclei (AGN) play a fundamental role in the evolution of their star formation histories. Both phenomena can be observed at work in NGC 6240, a local prototypical merger classified as an ultraluminous infrared galaxy (ULIRG) thanks to its elevated infrared luminosity. Interestingly, NGC,6240 hosts two AGN separated by 1.5 735 pc), detected in both X-ray and radio band. Taking advantage of the unprecedented sensitivity and wavelength coverage provided by the integral field unit (IFU) of the NIRSpec instrument on board JWST, we observed the nuclear region of NGC,6240 in a field of view of 3.7 times 3.7 1.9$ kpc^2) in order to investigate gas kinematics and interstellar medium (ISM) properties with a high spatial resolution of ∼ 0.1 (or ∼ 50 pc). We characterized the 2D stellar kinematics, separated the different gas kinematic components through multi-Gaussian fitting, and studied the excitation properties of the ISM from the near-infrared diagnostic diagram based on the H_2 1-0 γ $ and Fe II λ1.257μm/Paβ lines ratios. We isolated the ionization cones of the two nuclei and detected coronal line emission from both of them. Using H_2 line ratios, we found that the molecular hydrogen gas is excited mostly by thermal processes. We computed a hot molecular gas mass of $1.3 10^5$ M_⊙ and an ionized gas mass in the range of $10^5$ - $10^7$ M_⊙, depending on assumptions. We studied with unprecedented spatial resolution and sensitivity the kinematics of the molecular and ionized gas phases, and we revealed the complex structure of the molecular gas and found a blueshifted outflow near the southern nucleus, together with filaments connecting a highly redshifted H_2 cloud with the two nuclei. We speculate on the possible nature of this H_2 cloud and propose two possible scenarios: outflowing gas or a tidal cloud falling onto the nuclei.

Hydrogenation of Organic Molecules via Direct Mechanocatalysis.

Mechanochemical hydrogenation of unsaturated C-C and C-O, as well as N-O and C-X bonds is successfully achieved without the use of solvents, ligands, or catalyst powders via ball milling. A variety of catalysts are electroplated onto the walls of the milling vessel, allowing for simple recycling and reuse of the catalytic material. Hydrogen gas is directly introduced into the milling vessel, eliminating the need for hydrogen donor compounds which contribute to waste production and suboptimal atom economy. This approach enables the quantitative hydrogenation of unsaturated carbon-carbon bonds, achieving near-complete conversion within just 20 minutes at ambient temperature and pressures as low as 1.5 bar. Carbonyls, nitro groups, and organohalides were converted within reaction times of up to 12hours. Mechanistic investigations suggest the reaction to be following established mechanisms for hydrogenation. Finally, chemoselective hydrogenation of various reducible functional groups was explored, demonstrating the versatility and efficiency of this solvent-free mechanochemical approach with simple catalyst recycling for hydrogenation reactions.

Hydrogenation of Organic Molecules via Direct Mechanocatalysis

Mechanochemical hydrogenation of unsaturated C‐C and C‐O, as well as N‐O and C‐X bonds is successfully achieved without the use of solvents, ligands, or catalyst powders via ball milling. A variety of catalysts are electroplated onto the walls of the milling vessel, allowing for simple recycling and reuse of the catalytic material. Hydrogen gas is directly introduced into the milling vessel, eliminating the need for hydrogen donor compounds which contribute to waste production and suboptimal atom economy. This approach enables the quantitative hydrogenation of unsaturated carbon‐carbon bonds, achieving near‐complete conversion within just 20 minutes at ambient temperature and pressures as low as 1.5 bar. Carbonyls, nitro groups, and organohalides were converted within reaction times of up to 12 hours. Mechanistic investigations suggest the reaction to be following established mechanisms for hydrogenation. Finally, chemoselective hydrogenation of various reducible functional groups was explored, demonstrating the versatility and efficiency of this solvent‐free mechanochemical approach with simple catalyst recycling for hydrogenation reactions.

The endogenous hydrogen gas (H2) drives women’s health: a comment on “Gut bacteria convert glucocorticoids into progestins in the presence of hydrogen gas”

The endogenous hydrogen gas (H2) drives women’s health: a comment on “Gut bacteria convert glucocorticoids into progestins in the presence of hydrogen gas”

Epoxy-based vitrimeric semi-interpenetrating network/MXene nanocomposites for hydrogen gas barrier applications.

Herein, we report MXene-filled epoxy-based vitrimeric nanocomposites featuring a semi-interpenetrating network (S-IPN) to develop a hydrogen gas (H2) barrier coating with self-healing characteristics for compressed H2 storage applications. The reversible epoxy network was formed by synthesizing linear epoxy chains with pendent bis-hydroxyl groups using amino diol, which were then crosslinked with 1,4-benzenediboronic acid to generate dynamic boronic ester linkages. To achieve the S-IPN-type molecular arrangement, the epoxy chains were in situ crosslinked in the presence of poly(ethylene-co-vinyl alcohol) (EVOH), giving rise to a self-healing network (EEP) with a healing efficiency of 87%. Into the S-IPN vitrimer (EEP), a 2D platelet-type nanofiller MXene was incorporated to introduce a tortuous path for H2 gas diffusion along with improved mechanical properties. The nanocomposite coating was applied to nylon 6 liner material, which is conventionally used in all-composite H2 storage vessels. The application of a 2 wt% MXene/EEP nanocomposite coating showed a permeability coefficient of 0.062 cm3 mm m-2 d-1 atm-1 exhibiting ∼96% reduction in gas permeability compared to uncoated nylon 6. The same nanocomposite exhibited a healing efficiency of 79%. Increasing the MXene loading to 10 wt% further reduced the permeability coefficient to 0.002 cm3 mm m-2 d-1 atm-1; however, the healing efficiency decreased due to restricted chain mobility. In essence, the current work highlights the potential of vitrimeric S-IPN nanocomposite coatings for H2 gas-barrier applications, enhancing safety and performance.

Socio-Economic Impact Assessment of Hydrogen Injection in the Natural Gas Network

This study explores the feasibility parameters of a potential investment plan for injecting “green” hydrogen into the existing natural gas supply network in Greece. To this end, a preliminary profitability optimization analysis was conducted through key performance indicators such as the cost of hydrogen and the socio-environmental benefit of carbon savings, followed by break-even and sensitivity analyses. The identification of the major impact drivers of the assessment was based on the examination of a set of operational scenarios of varying hydrogen and natural gas flow rates. The results show that high natural gas capacities with a 5% hydrogen content by volume are the optimal case in terms of socio-economic viability, but the overall profitability is too sensitive to hydrogen pricing, rendering it unfeasible without additional motives, measures and pricing strategies. The results feed into the main challenge of implementing commercial “green” hydrogen infrastructures in the market in a sustainable and feasible manner.

Modeling an Electrolyzer in a Graph-Based Framework

We propose a linear electrolyzer model for steady-state load flow analysis of multi-carrier energy networks, where the electrolyzer is capable of producing hydrogen gas and heat. For our electrolyzer model, we show that there are boundary conditions that lead to a well-posed problem. We derive these conditions for two cases, namely with a known and unknown heat efficiency parameter. Furthermore, the derived conditions are validated numerically. Moreover, we investigate the extensibility of our model by including nonlinear models from electricity, gas, and heat. In this setting, we derived boundary conditions based on our previous findings. Due to the involvement of nonlinearity, it is a challenge to prove that the boundary conditions lead to a well-posed problem. Therefore, we simulated the electrolyzer connected with an electricity, gas, and heat system. Additionally, we considered a known and unknown heat efficiency parameter. The numerical results support that the linear electrolyzer model is solvable in a multi-carrier energy network.

A decade of breakthroughs: MOF-graphene oxide catalysts for water splitting efficiency

Abstract Burning fossil fuels has significantly worsened environmental pollution, particularly due to the release of carbon dioxide emissions. The global efforts to promote renewable energy solutions, like electrocatalytic water splitting, have gained momentum. Scientists are focusing on the development of sustainable methods like water splitting to reduce dependence on conventional fuels. Developing affordable and effective electrocatalysts is crucial for multifunctional electrochemical water splitting (ECWS). In comparison to traditional electrocatalysts, metal-organic frameworks (MOFs) exhibit favorable catalytic performance for electrochemical water decomposition because of their plentiful porosity, surface area, and topologies for enhanced production of hydrogen (H2) and oxygen (O2) gas. When combined with MOF, graphene creates a synergistic hybrid nanomaterial that is more stable, adaptable, and durable. The primary goal of this review article is to conduct an in-depth investigation of the latest advancements in MOFs and MOF-GO electrocatalysts for water electrolysis. Herein, we have covered the plausible mechanism for the overall water-splitting electrocatalytic processes and several important factors influencing their electrocatalytic response. We also discussed the recent progress in the performance and stability of MOFs and MOF-GO electrocatalysts for water-splitting reactions. Finally, the article highlights the challenges and application of MOF and MOF-GO composites and the future preference for water-splitting applications.

Synthesis and characterization of Co-W alloy coatings for enhanced hydrogen evolution: effects of bath composition and deposition parameters

This study explores the development of Co-W alloy coatings as efficient electrode materials for the hydrogen evolution reaction (HER), offering new insights into their performance. Using a specially formulated electrolyte bath with glycerol as an additive, Co-W alloy coatings were deposited on copper under different [Co2+]/[WO4 2−] molar ratios. Their electrocatalytic efficiency was evaluated in 1 M KOH through cyclic voltammetry (CV), chronopotentiometry (CP), and hydrogen gas measurements using a custom glass device. The results showed that the combination of Co and W in the coatings significantly enhances performance, as confirmed by SEM, XRD, and EDS analyses. Potentiodynamic polarization studies further explained the HER mechanisms. This work introduces a unique bath composition and demonstrates how optimizing the alloy composition can improve HER activity, paving the way for better electrocatalysts. The study identified that the Co-W coating prepared using a 0.35 M solution at a current density of 1 Adm2 demonstrated the highest electrocatalytic efficiency. This performance was attributed to the tungsten content of approximately 30 wt% and the maximum hydrogen evolution observed under these optimized conditions. The hydrogen evolution reaction (HER) in Co-W alloys follows the Volmer-Heyrovsky mechanism, characterized by the rapid evolution of hydrogen.

Nano-Structured InGaN Photoanode for Hydrogen Production Using Photoelectrochemical Water Splitting: A Simulation Study

Abstract InGaN nanostructures have emerged as a promising solution for developing efficient and stable photoelectrodes for hydrogen production using photoelectrochemical (PEC) water splitting. In this work, we investigate the performance of an InGaN nanopyramid photoanode through electrical and optical simulations. The simulated structure consists of a p-GaN/InGaN NP /n-GaN nanopyramid with 12 pairs of TiO2/SiO2 dielectric Bragg reflector. We obtain a short-circuit current and a power density of 12.23 mA/cm2 and 16 mW/cm2, respectively. We also compare the photoelectrochemical properties of the InGaN nanopyramid photoanode and a planar InGaN photoanode. The incident photon conversion efficiency of the InGaN nanopyramid reaches 43% compared to 9.5% in the case of planar InGaN photoanode. The hydrogen evolution rate of the InGaN NP reaches 228 µmol.cm-2.h-1, which is four times higher than the planar InGaN photoanode. As for solar-to-hydrogen efficiency, we obtained 15% and 3% for InGaN nanopyramid and planar InGaN photoanode, respectively. Our results suggest that InGaN nanopyramids can serve as an efficient photoanode to produce hydrogen gas via PEC water splitting.

Molecular hydrogen reduces dermatitis-induced itch, diabetic itch and cholestatic itch by inhibiting spinal oxidative stress and synaptic plasticity via SIRT1-β-catenin pathway in mice.

Chronic itch which is primarily associated with dermatologic, systemic, or metabolic disorders is often refractory to most current antipruritic medications, thus highlighting the need for improved therapies. Oxidative damage is a novel determinant of spinal pruriceptive sensitization and synaptic plasticity. The resolution of oxidative insult by molecular hydrogen has been manifested. Herein, we strikingly report that both hydrogen gas (2%) inhalation and hydrogen-rich saline (5mL/kg, intraperitoneal) injection prevent and alleviate persistent dermatitis-induced itch, diabetic itch and cholestatic itch. Hydrogen therapy reverses the decrease of spinal SIRT1 expression and antioxidant enzymes (SOD, GPx and CAT) activity after dermatitis, diabetes and cholestasis. Furthermore, hydrogen reduces spinal ROS generation, oxidation products (MDA, 8-OHdG and 3-NT) accumulation, β-catenin acetylation and dendritic spine density in persistent itch models. Spinal SIRT1 inhibition eliminates antipruritic and antioxidative effects of hydrogen, while SIRT1 agonism attenuates chronic itch phenotype, spinal β-catenin acetylation and mitochondrial damage. β-catenin inhibitors are effective against chronic itch via reducing β-catenin acetylation, blocking ERK phosphorylation and elevating antioxidant enzymes activity. Hydrogen treatment suppressed dermatitis and cholestasis mediated spontaneous excitatory postsynaptic currents in vitro. Additionally, hydrogen impairs cholestasis-induced the enhancement of cerebral functional connectivity between the right primary cingulate cortex and bilateral sensorimotor cortex, as well as bilateral striatum. Taken together, this study uncovers that molecular hydrogen protects against chronic pruritus and spinal pruriceptive sensitization by reducing oxidative damage via up-regulation of SIRT1-dependent β-catenin deacetylation in mice, implying a promising strategy in translational development for itch control.

Influence of Hydrogen Introduced Drying Atmosphere on Drying Kinetics, Phenolic Profile, and Rehydration Behavior of Tomato Slices

ABSTRACTThe current study performed drying of tomato slices in a drying atmosphere with hydrogen gas (RADMIX; a gaseous mixture of 4% hydrogen, 5% carbon dioxide and 91% nitrogen), and compared with 100% air, 100% nitrogen drying environments. All the drying experiments were carried out at 60°C. Control samples and pretreated samples with 1% Potassium metabisulfite (KMS) treated samples were dried to a final moisture content of around 13.29% to 13.70% (wet basis), respectively. The drying behavior and quality characteristics including color change (ΔE), lycopene retention, total phenolics and rehydration ratio of the dried products were studied. The better retention of color and quality was observed in the sulfite pretreated and RADMIX dried sample. The color change (ΔE) was found to be 10.1, lycopene retention by 94.28% (3.3 mg/100 g), and the maximum rehydration ratio of 4.67 were observed in samples subjected to reduced atmospheric drying. Additionally, the color change was lesser for samples pretreated with KMS than the control samples. It was found that the use of hydrogen gas at 4% concentration (RADMIX) in the drying environment significantly impacted quality parameters of tomato slices. The sulfite pretreatment was advantageous technique in terms of moisture diffusivity, antioxidant compounds retention and rehydration ratio of tomato slices.

Performance investigation of neoteric Pt/Pd Junctionless gas tube FET(JL-GT-FET) as a Hydrogen(H2) gas sensor for industrial applications-analytical model

Performance investigation of neoteric Pt/Pd Junctionless gas tube FET(JL-GT-FET) as a Hydrogen(H2) gas sensor for industrial applications-analytical model

Comparison of gaseous hydrogen effects in 1200 MPa high strength martensitic and pearlitic steels

Comparison of gaseous hydrogen effects in 1200 MPa high strength martensitic and pearlitic steels

Experimental DMD Analysis of Combustion Modes and Instabilities in a Scramjet Combustor

The combustion characteristics of a gaseous hydrogen fueled scramjet combustor were experimentally investigated through single-shot micro-pulse detonation engine (μPDE) operations across a range of fuel injection pressures and corresponding equivalence ratios. This study utilized a lab-scale direct-connect scramjet combustor integrated with a μPDE, designed to simulate flight conditions at Mach numbers between 4.0 and 5.0 at altitudes of 20 to 25 km. Static wall pressure was measured using 16 pressure probes from the isolator to the scramjet combustor at a sampling rate of 500 Hz. Additionally, Z-fold type Schlieren and flame luminosity were captured using a high-speed camera in a test section equipped with a quartz visualization window. Experiments were conducted under five conditions with equivalence ratios ranging from 0.10 to 0.55, each performed three times to ensure repeatability. Fast Fourier transform (FFT) and dynamic mode decomposition (DMD) analyses were applied to the pressure and image data obtained. Although auto-ignition was not achieved in all cases, combustion persisted while fuel was injected following the single-shot μPDE ignition. This allowed for the identification of distinct combustion modes according to equivalence ratio, by observing the dominant flame types and the shock structure within the flow of the combustor. These combustion modes showed different types of instability.

Process performance of in-situ bio-methanation for co-digestion of sewage sludge and lactic acid, aiming to utilize waste poly-lactic acid as methane

This study examined hydrogen conversion efficiency and operational stability in pilot-scale in-situ bio-methanation during the co-digestion of sewage sludge and lactic acid (partially derived from waste poly-lactic acid). Parallel laboratory-scale experiments were also conducted. In the pilot, hydrogen conversion efficiency decreased from 98.9 % to 84.4 % as the hydrogen feed rate increased from 240 to 1,200 mL/LR/d. Conversely, laboratory experiments maintained efficiencies above 95 % at a feed rate of 3,600 mL/LR/d, suggesting that hydrogen gas–liquid transfer limited hydrogen conversion efficiency in the pilot. Lactic acid degradation was observed both with and without hydrogen injection in the pilot. Methane yields from the acid were 310 ± 30 and 300 ± 30 mL/g (chemical oxygen demand (COD))-added, close to the theoretical methane yield (350 mL/gCOD). These results demonstrate the importance of hydrogen gas–liquid transfer when scaling up bio-methanation processes. Moreover, they showed the potential of waste poly-lactic acid as a methane source.

High-efficient and selective hydrogen gas sensor based on bimetallic Ag/Cu nanoparticles decorated on In2O3: Experimental and DFT calculation

High-efficient and selective hydrogen gas sensor based on bimetallic Ag/Cu nanoparticles decorated on In2O3: Experimental and DFT calculation

Electronic and adsorption characteristics of hydrogen cyanide (HCN) and isocyanide (HNC) on intrinsic and doped phosphorene

Density functional theory calculations are performed to investigate the electronic properties of the phosphorene that is substituted with the non-metals in different patterns and concentrations and to study the adsorption of the toxic gases, hydrogen cyanide (HCN) and isocyanides (HNC), on the intrinsic and nitrogen-doped phosphorene adsorbents. It has been established previously that the number of valence electrons in the dopant atoms considerably affects the electronic characteristics of phosphorene. Doping with B, S, Si, and other non-metals has resulted in drastic changes in the direct bandgap characteristics of the semiconductor, resulting in the conversion of the semiconductor into an indirect bandgap material (boron-doped) or metallic (Si/S doped). Of all the doped surfaces, only nitrogen-doped phosphorene shows a direct bandgap. Therefore, adsorption studies are conducted to investigate the sensitivity of the toxic gases hydrogen cyanide (HCN) and isocyanide (HNC) on intrinsic and nitrogen-doped adsorbents. The adsorption results are compared to those on graphene and doped graphene surfaces. Pure phosphorene is a good candidate for the moderate adsorption of HCN and HNC due to its low adsorption energy and charge transfer. We have also found that intrinsic phosphorene is a better adsorbent for these gases than intrinsic graphene and doped graphene. In addition, N-doped phosphorene shows moderate reactivity toward HCN and HNC gases, suggesting it may be used as a metal-free catalyst for the adsorption of these adsorbates. The 2p orbitals on the nitrogen of HCN are found to play a significant role in the strong physisorption.

Exploration of Multidimensional Structural Optimization and Regulation Mechanisms: Catalysts and Reaction Environments in Electrochemical Ammonia Synthesis.

Ammonia (NH3) is esteemed for its attributes as a carbon-neutral fuel and hydrogen storage material, due to its high energy density, abundant hydrogen content, and notably higher liquefaction temperature in comparison to hydrogen gas. The primary method for the synthetic generation of NH3 is the Haber-Bosch process, involving rigorous conditions and resulting in significant global energy consumption and carbon dioxide emissions. To tackle energy and environmental challenges, the exploration of innovative green and sustainable technologies for NH3 synthesis is imperative. Rapid advances in electrochemical technology have created fresh prospects for researchers in the realm of environmentally friendly NH3 synthesis. Nevertheless, the intricate intermediate products and sluggish kinetics in the reactions impede the progress of green electrochemical NH3 synthesis (EAS) technologies. To improve the activity and selectivity of the EAS, which encompasses the electrocatalytic reduction of nitrogen gas, nitrate, and nitric oxide, numerous electrocatalysts and design strategies have been meticulously investigated. Here, this review primarily delves into recent progress and obstacles in EAS pathways, examining methods to boost the yield rate and current efficiency of NH3 synthesis via multidimensional structural optimization, while also exploring the challenges and outlook for EAS.

Enhanced Performance and Emission Characteristics of Soybean Biodiesel using TiO2 Nanoparticles in CRDI Engines: A Comprehensive Analysis

Renewable and clean energy sources must replace conventional ones due to the dangerous effects of fossil fuel pollution. The impact of incorporating hydrogen and TiO2 nanoparticles into Soybean biodiesel and its CRDI engine performance was assessed in this study. For engine operations, a 10 L/min hydrogen flow and 75 ppm of the nanoparticle also used. Experiments comparing diesel engines running on clean diesel to those with a B15 biodiesel mix (75% diesel and 15% biodiesel) found that the latter had better performance, and combustion behaviour with the inclusion of both hydrogen gas and cenoxite oxide. Brake fuel consumption was 16.12% lower and brake thermal efficiency was 3.53% better than diesel at 80% loading condition. By incorporating nanoparticles and hydrogen into the biodiesel mixture, we were able to reduce CO emission by 30%, HC by 50%, and smoke by 42%. On the other hand, comparisons to diesel showed an 12.15% rise in NOx. A mix of hydrogen and TiO2 nanoparticles produced biodiesel with 9% greater in-cylinder pressure and 7% higher HRR. More power and efficiency from the engine are the outcomes of this blend's low ignition delay period under full load conditions. This experimental work has paved the path for diesel engines to run on biodiesel that is hydrogen-enriched and combined with nanoparticles.