Low Hydrogen Concentration Research Articles

Effects of silver diffusement on TiO2-B2O3 nanocomposite sensor towards hydrogen sensing

ABSTRACT Various finger dimensions of interdigitated electrodes in TiO2-B2O3 nanocomposite sensors were proposed in this study. To study the silver diffusement effect on the hydrogen sensing characteristics at different operating temperatures. The result showed that some of the silver particles diffused to the surface of the TiO2-B2O3 nanocomposite sensor after the annealing process at 500°C. The amount of silver particles diffused into the TiO2-B2O3 surface was contributed by the finger dimension of the interdigitated electrode used in the nanocomposite sensor. The results revealed that the structure of interdigitated electrodes in T65 nanocomposite sensor enhanced the performance at low hydrogen concentrations with response values were approximately 4.78, 11.47, 14.47, 16.58, and 20.00 for 100 ppm, 300 ppm, 500 ppm, 700 ppm, and 1000 ppm, respectively, at the optimum operating temperature of 200°C. The activation energy for all nanocomposite sensors was approximately in the range of 40–70 kJ/mol.

Detection of diffusible hydrogen during laser beam welding under water

A critical damage pattern in underwater welding processes is the formation of hydrogen-induced cold cracks, which do not occur immediately after welding. The electrolytic dissociation of the water during arc welding creates a large supply of hydrogen. As an alternative, laser beam welding could be used in the underwater industry in the future. A low hydrogen concentration is expected due to thermal dissociation only. In this paper, laser beam welds are performed with Yb:YAG-laser on 10 mm S235JR-steel and the diffusible hydrogen content of this samples is determined using carrier gas hot extraction. The laser beam power is varied between 3 kW and 4 kW and the feed rate between 0.25 m/min and 0.50 m/min to analyse their influence on the hydrogen content. In addition, the process zone is analysed about hydrogen formation using a high-speed camera and spectrometer. The results are compared with the hydrogen content of shielded metal arc-welded samples.

Layered CrO2·nH2O as a cathode material for aqueous zinc-ion batteries: ab initio study.

Aqueous zinc-ion batteries are considered potential large-scale energy storage systems due to their low cost, environmentally friendly nature, and high safety. However, the development of high energy density cathode materials and uncertain reaction mechanisms remains a major challenge. In this work, the reaction mechanism, discharge voltage and diffusion properties of layered CrO2 as a cathode material for aqueous zinc-ion batteries were studied using first-principles calculations, and the effect of pre-intercalated structural water on the electrochemical performance of CrO2 electrodes is also discussed. The results show that CrO2 exhibits high average discharge voltages (2.65 V for H insertion (pH = 7) and 1.97 V for Zn insertion) and medium theoretical capacities (319 mA h g-1 (H and Zn)). The H intercalation voltage strongly depends on the pH value of the electrolyte. The H/Zn co-insertion mechanism occurs at low hydrogen concentrations (c(H) ≤ 0.125), where the initial insertion of H reduces the total amount of subsequent Zn insertion. For the substrate containing structured water (CrO2·nH2O, n ≥ 0.5), the average voltage of Zn insertion is significantly increased, while the average voltage of H slightly decreases. In addition, the pre-intercalated water strategy significantly improved the diffusion properties of H and Zn. This study shows that layered CrO2·nH2O is a promising cathode material for aqueous zinc-ion batteries, and also provides theoretical guidance for the development of high-performance cathode materials for aqueous zinc-ion batteries.

Numerical modelling of hydrogen leakages in confined spaces for domestic applications

The UK government tentatively plans to use hydrogen for domestic applications by 2035. While the use of hydrogen aims to reduce the dependence on hydrocarbons, certain factors need consideration. Since hydrogen is much lighter, and more reactive than methane, it is crucial to understand the change in risk for accident scenarios involving hydrogen in a domestic setting. Numerical modelling was used to simulate the leakage of hydrogen and methane in small, enclosed spaces such as kitchen cupboards. The k- ε turbulence model was used along with the species transport model to simulate the leakage of gas for different inlet locations and leak diameters (1.8 mm–7.2 mm). From the modelling study, it was observed that hydrogen and methane both tend to stratify from top of the control volume to the bottom. The key finding was that, under adverse conditions (leak from a 7.2 mm diameter hole) and due to greater volumetric flow, hydrogen tends to reach equilibrium concentration 45s faster than methane for a total leak duration of 600s. Additionally, it was noted that cases with leak inlet locations near corners had 28% lower hydrogen concentrations, and 25% lower methane concentrations as compared to leak inlet locations near the centre of the cupboard.

An Autonomous Mobile Combination Disinfection System.

To address the common drawbacks of current disinfection robots, which include the potential for secondary environmental pollution, disinfection dead corners, and low efficiency, in this paper, an autonomous mobile combination disinfection system is proposed. The system utilizes ultraviolet (UV) radiation and a low-concentration hydrogen peroxide aerosol to kill pathogens. It comprises three parts: a human-computer interface, a mobile robot, and disinfection equipment. A disinfection process model with continuous and fixed-point modes was established, and the effective disinfection range, speed, and duration were quantitatively calculated. The developed prototype was tested on-site by a professional third-party testing agency. The experimental results demonstrated that the combination disinfection robot achieved a 92.95% disinfection rate of natural airborne bacteria in a room measuring 22 square meters with a height of 2.8 m in just 30 min. The disinfection efficiency is at least 25% higher compared to standalone UV lamp disinfection and also exhibits a noticeable improvement over standalone hydrogen peroxide aerosol disinfection. The system enables the environmentally friendly, rapid, efficient, and all-encompassing disinfection of natural airborne bacteria. Finally, various disinfection solutions and recommendations for different application scenarios and requirements are provided.

Fabrication and characterization of highly responsive hydrogen sensor based on Fe2O3:ZnO nanostructured thin film

This work aimed to manufacture a highly sensitive hydrogen gas sensor based on Fe2O3:ZnO thin film. The Fe2O3:ZnO based sputtering target was synthesized by a solid-state synthesis method. Gas-sensitive thin films were deposited onto the alumina substrate by the high-frequency (RF) magnetron sputtering method. The thickness of the sensing film was measured and the morphology of the sensing layers was studied. The Fe2O3:ZnO sensor showed the highest hydrogen gas response at 100 ᵒC and the operating temperature of 150 ᵒC was selected as the optimum working temperature. The sensor showed sensitivity even to extremely low concentrations of hydrogen (100 ppm), where the response was 4.6. The sensing parameters of the fabricated sensor confirm that the Fe2O3:ZnO material may become an excellent nanostructure for the detection of low concentrations of hydrogen.

Magnetic-acoustic actuated spinous microrobot for enhanced degradation of organic pollutants

A growing interest in the development of efficient strategies for the removal of organic pollutants from polluted water is emerging. As such, artificial micro/nano machines performing excellent water purification tasks have recently attracted more research attention of scientists. Hereby a spinous Fe3O4@PPy microrobot is presented that towards an efficient organic pollutant removal by enhancing Fenton-like reaction. The microrobot is fabricated by wrapping polypyrrole (PPy) on a spiny magnetic template prepared from sunflowers pollen. Modulating the sound pressure and frequency of the ultrasonic field enables the Fe3O4@PPy microrobot to present multimode motion, such as violent eruption-like motion caused by local cavitation (ELM), march-like unific motion (MLM), and typhoon-like rotation toward the center gathered motion (TLM). This multimode motion achieves the sufficient locomotion of microrobots in three-dimensional space and effective contact with organic pollutants in polluted water. Furthermore, a 5.2-fold increase in the degradation rate of methylene blue has been realized using Fe3O4@PPy microrobots under low-concentration hydrogen peroxide conditions. Also, the magnetically controlled recovery of microrobots from water after the completion of the degradation task has been demonstrated. The magnetic-acoustic actuated spinous microrobot can be extrapolated to other catalytic microrobot, developing a new strategy for an easier implementation and recovery of microrobot in real applications of water purification.

The Geophysical Properties of FeHx Phases Under Inner Core Conditions

AbstractHydrogen has been proposed as an important light element in planetary iron cores, while the crystal structure and thermoelasticity of FeHx (x = 1) (FeH hereafter) under inner core conditions remain largely unknown. Recent studies report that FeH adopts an face‐centered cubic (fcc) structure up to core conditions. In this study, using ab initio molecular dynamics, we calculate the free energy and elastic properties of FeH at high P‐T conditions. Our results indicate that the hexagonal close‐packed (hcp) structure of FeHx is favored by both the low hydrogen concentration and the elevated temperature of inner‐core conditions. We also clarify that lattice hydrogen hardens the wave velocities of iron while superionic hydrogen softens it. Both fcc‐ and hcp‐FeH can match inner‐core wave velocities and Poisson's ratio, which supports the hypothesis of hydrogen as a vital light element in the Earth's core.

Annealing cracking in Zr and a Zr-alloy with low hydrogen concentration

Hydrogen embrittlement, also known as hydrogen-induced cracking, is a longstanding concern for zirconium (Zr) and its alloys. The affinity for hydrogen in zirconium results in the formation of brittle hydrides. Hydrides are conventionally thought to facilitate crack propagation, and the prevailing recommendation to hinder hydride embrittlement involves reducing the hydrogen concentration in the material and applying slow cooling to reduce thermal stresses. Here, in Zr with a maximum hydrogen concentration of 43 wppm, we show that cracks initiate unexpectedly after annealing, a step that involves slow cooling and no external stress. With a suite of high-resolution microscopy, we show that annealing cracks initiate at prismatic δ-hydrides, whose presence is unexpected. The microscopic annealing crack paths are consequently crystallographic, following the habit plane of these prismatic δ-hydrides. The commonly reported γ-hydride and δ-hydrides that develop on the basal plane are found not to initiate cracks. We rationalize that prismatic δ hydrides result from the intergranular thermal residual stresses that develop during slow cooling. This finding of uncommon annealing cracking further advances the mechanistic understanding of hydride embrittlement in zirconium and can lead to new strategies for design and fabrication of advanced zirconium alloys for harsh environments.

Exploring the structural, physical properties and hydrogen storage properties of LiBHx(x=1 and 4) lithium borohydrides

To explore the correlation between the hydrogen concentration and electronic properties of the lithium borohydrides (LiBHx), we apply the first-principles method to study the influence of hydrogen (H) concentration on the structural stability, physical properties and hydrogen storage properties of LiBHx(x = 1 and 4). Two hydrogen concentrations are considered. The calculated results show that three LiBHx phases are thermodynamic stability because of the negative formation enthalpy. LiBH with the low concentration of hydrogen has better thermodynamic stability in comparison to LiBH4. In particular, the calculated gravimetric hydrogen storage capacity is 5.06 wt% for LiBH and 15.53 wt% for LiBH4, respectively. Essentially, the higher hydrogen storage capacity of LiBH4 is related to the product of [BH4] group because of the strong electronic interaction between B atom and H atom. Based on the m-GGA function, it is found that the calculated band gap is 0.044 for LiBH, 7.744 eV for the hexagonal LiBH4 and 7.908 eV for the orthorhombic LiBH4, respectively. Naturally, the calculated electronic structure shows that the wide band gap is related to the band separation between H-s state, Li-state and B-2p state near the Fermi level.

Minimum Detection Concentration of Hydrogen in Air Depending on Substrate Type and Design of the 3ω Sensor.

Hydrogen has emerged as a promising carbon-neutral fuel source, spurring research and development efforts to facilitate its widespread adoption. However, the safe handling of hydrogen requires precise leak detection sensors due to its low activation energy and explosive potential. Various detection methods exist, with thermal conductivity measurement being a prominent technique for quantifying hydrogen concentrations. However, challenges remain in achieving high measurement sensitivity at low hydrogen concentrations below 1% for thermal-conductivity-based hydrogen sensors. Recent research explores the 3ω method's application for measuring hydrogen concentrations in ambient air, offering high spatial and temporal resolutions. This study aims to enhance hydrogen leak detection sensitivity using the 3ω method by conducting thermal analyses on sensor design variables. Factors including substrate material, type, and sensor geometry significantly impact the measurement sensitivity. Comparative evaluations consider the minimum detectable hydrogen concentration while accounting for the uncertainty of the 3ω signal. The proposed suspended-type 3ω sensor is capable of detecting hydrogen leaks in ambient air and provides real-time measurements that are ideal for monitoring hydrogen diffusion. This research serves to bridge the gap between precision and real-time monitoring of hydrogen leak detection, promising significant advancements in the related safety applications.

A hydrogen-vanadium rebalance cell based on ABPBI membrane operating at low hydrogen concentration to restore the capacity of VRFB

A hydrogen‑vanadium rebalance cell (HVRC) is developed to address the capacity degradation and hydrogen explosion risks in long-term operations of all‑vanadium liquid flow battery (VRFB). Different operating conditions was evaluated in this study to investigate the cell's performance focusing on low hydrogen concentrations (4 %). The HVRC achieved a stable rebalance process with a meager hydrogen stoichiometry ratio of 1.15 at 300 mA cm−2. The use of PFSA membranes was found to be problematic due to the contradictory issues of unstable battery operation without humidification and severe vanadium ion loss with humidification. Therefore, ABPBI membrane was used instead of PFSA membrane to reduce vanadium ion crossover and Pt catalyst corrosion. HVRC based on ABPBI membrane completed a 100 h stability test at 70 mA cm−2 with a stoichiometric ratio of hydrogen of 1.23. The vanadium ion crossover of ABPBI-HVRC was less than 1/6 that of PFSA-HVRC, and no significant platinum dissolution occurred during 100 h operation without humidification. The reliability of the ABPBI-HVRC in intermittent operation mode has also been verified. These results illustrate the HVRC offers a promising measure to eliminate safety issues and restore capacity in VRFB systems. Additionally, incorporating the ABPBI membrane in the HVRC holds greater promise for enhancing its stability.

Determination of Stable Hydrogen Isotopic Composition and Isotope Enrichment Factor at Low Hydrogen Concentration.

Determination of stable hydrogen isotopic compositions (δ2H) is currently challenged to achieve a high detection limit for reaching the linear range where δ2H values are independent of concentration. Therefore, it is difficult to assess precise δ2H values for calculating the hydrogen isotope enrichment factor (εH) and for field application where the concentrations of contaminants are relatively low. In this study, a data treatment approach was developed to obtain accurate δ2H values below the linear range. The core concept was to use a logarithmic function to fit the δ2H values below the linear range and then adjust the δ2H values below the linear range into the linear range by using the fitted logarithmic equation. Moreover, the adjusted δ2H values were calibrated by using laboratory reference materials, e.g., n-alkanes. Tris(2-chloroethyl) phosphate (TCEP) and hexachlorocyclohexane (HCH) isomers were selected as examples of complex heteroatom-bearing compounds to develop the data treatment approach. This data treatment approach was then tested using δ2H values from a TCEP transformation experiment with OH radicals. Comparable δ2H values and εH between the low-concentration experiment and the reference experiment were obtained using the developed approach. Therefore, the developed data treatment approach enables a possibility of determining the hydrogen isotopic compositions of organic components in low concentrations. It is especially valuable for determining organic contaminants in environmental samples, which are usually present in low concentrations.

Inhibition of retinal ischemia-reperfusion injury in rats by inhalation of low-concentration hydrogen gas.

To investigate the inhibitory effect of hydrogen gas inhalation on retinal ischemia reperfusion (I/R) injury using a rat model. Six-week-old male Sprague-Dawley rats were used. A 27G needle connected by a tube to a saline bottle placed 200cm above the eye was inserted into the anterior eye chamber to create a rat retinal I/R model. In the ischemia-plus-hydrogen-gas group (H2( +) group), the ischemia time was set to 90min, and 1.8% hydrogen was added to the air delivered by the anesthesia mask simultaneously with the start of ischemia. In the non-hydrogen-treatment ischemia group (H2( -) group), I/R injury was created similarly, but only air was inhaled. ERGs were measured; after removal of the eyes, the retina was examined for histological, immunostaining, and molecular biological analyses. The mean thickness of the inner retinal layer in the H2( +) group was 107.2 ± 16.0μm (n = 5), significantly greater than that in the H2( -) group (60.8 ± 6.7μm). Immunostaining for Iba1 in the H2( -) group showed increased numbers of microglia and microglial infiltration into the subretinal space, while there was no increase in microglia in the H2( +) group. B-wave amplitudes in the H2( +) group were significantly higher than in the H2( -) group. In the membrane antibody array, levels of interleukin-6, monocyte chemotactic protein 1, and tumor necrosis factor alpha were significantly lower in the H2( +) group than in the H2( -) group. Inhalation of 1.8% hydrogen gas inhibited the induction of inflammation, morphological/structural changes, and glial cell increase caused by retinal I/R injury.

Ultrafast response of Pt functionalized Fe2(MoO4)3 nanoflower gas sensors for ultra-low ppm level H2 gas detection

The high and ultrafast response of hydrogen gas sensors is very critical during H2 transportation and storage. For detecting the ultra-low ppm level H2, a new Pt functionalized Fe2(MoO4)3 (FMO) nanoflower gas sensor (Pt/Fe2(MoO4)3 briefed as Pt/FMO) was fabricated in this work by a simple solvothermal method and calcination process. The Pt/FMO gas sensor shows excellent H2 sensing performances, which can be attributed to the high catalytic activity of Pt and the large surface area of 3D FMO. The optimal operating temperature of Pt/FMO was investigated and determined at 300 °C. The response/recovery time of Pt/FMO was only 16/38 s, which displayed excellent stability and ultrafast response/recovery time toward ultra-low ppm level H2 (10 ppm) at 300 °C, respectively. The enhancement mechanism was also studied and discussed. This newly developed gas sensor may have great application potential in the rapid detection of low-concentration hydrogen gas.

Numerical investigation on the effect of hydrogen share in NH3/H2 blends in a turbulent lean-premixed swirl burner

Climate change and the energy crisis urge the transition from fossil to renewable fuels. Ammonia and hydrogen are the most versatile carbon-free chemical energy carriers. Hydrogen-diluted ammonia combustion can drastically lower the emission of nitrogen oxides. The present paper focuses on the numerical analysis of ammonia/hydrogen combustion in a lean-premixed swirl burner, highlighting the effect of hydrogen share and equivalence ratio. The hydrogen share notably influences the axial position of the heat release maximum due to the higher reactivity, while it marginally influences the global velocity field. Unburned ammonia was observed at lean condition and low hydrogen concentration. At ultra-lean conditions, nitrogen oxide emission increases with hydrogen content, while a maximum can be reached by increasing the equivalence ratio. The values are compared to experimental data from the literature. Dinitrogen oxide emission decreases with both hydrogen concentration and equivalence ratio. Non-reacting flow field was validated by Particle Image Velocimetry measurements.

Rumen Lachnospiraceae isolate NK3A20 exhibits metabolic flexibility in response to substrate and coculture with a methanogen.

Hydrogen (H2) is the primary electron donor for methane formation in ruminants, but the H2-producing organisms involved are largely uncharacterized. This work integrated studies of microbial physiology and genomics to characterize rumen bacterial isolate NK3A20 of the family Lachnospiraceae. Isolate NK3A20 was the first recognized isolate of the NK3A20 group, which is among the ten most abundant bacterial genera in 16S rRNA gene surveys of rumen microbiota. NK3A20 produced acetate, butyrate, H2, and formate from glucose. The end product ratios varied when grown with different substrates and at different H2 partial pressures. NK3A20 produced butyrate as a major product using glucose or under high H2 partial pressures and switched to mainly acetate in the presence of galacturonic acid (an oxidized sugar) or in coculture with a methanogen. Growth with galacturonic acid was faster at elevated H2 concentrations, while elevated H2 slowed growth with glucose. Genome analyses revealed the presence of multiple hydrogenases including a membrane-bound Ech hydrogenase, an electron bifurcating butyryl-CoA dehydrogenase (Bcd-Etf), and an Rnf complex that may be involved in modulating the observed metabolic pathway changes, providing insight into H2 formation in the rumen. IMPORTANCE The genus-level NK3A20 group is one of the ten most abundant genera of rumen bacteria. Like most of the rumen bacteria that produce the hydrogen that is converted to methane in the rumen, it is understudied, without any previously characterized isolates. We investigated isolate NK3A20, a cultured member of this genus, and showed that it modulates hydrogen production in response to its growth substrates and the hydrogen concentration in its environment. Low-hydrogen concentrations stimulated hydrogen formation, while high concentrations inhibited its formation and shifted the fermentation to more reduced organic acid products. We found that growth on uronic acids, components of certain plant polymers, resulted in low hydrogen yields compared to glucose, which could aid in the selection of low-methane feeds. A better understanding of the major genera that produce hydrogen in the rumen is part of developing strategies to mitigate biogenic methane emitted by livestock agriculture.

Influence of annealing on gas sensing properties of WO3 thin films

Tungsten trioxide (WO3) is a wide-bandgap semiconductor. Its advantages include highchemical stability and low price. Furthermore, WO3 has chromogenic properties, that is, the abilityto switch between pale yellow and dark blue in response to various stimuli, including temperature,light irradiation, electric field, and exposure to hydrogen. Due to its high colouring efficiency andfast switching, it can be used in antidazzling mirrors and smart window applications, as well as in gassensing. In this paper, we present the influence of annealing on the properties of WO3 coatings that wereannealed at temperatures in the range from 200C to 400C. The sensing response was characterisedbased on the transmittance measurement during exposure to air and Ar/H2 mixture with hydrogenconcentrations from 25 ppm to 1000 ppm. Furthermore, the influence of annealing on the structureand morphology of the coatings was examined. Annealing at 400C led to a structure change fromamorphous to crystalline one. After the introduction of the Ar/H2 mixture, a decrease in transmittancewas observed for all of the analysed coatings. For films annealed at 200C and 300C, the transmittancevalue decreased during the entire colouring cycle, while for the coating annealed at 400C a plateau wasreached after 7 minutes of exposure. It was found that the best sensing characteristics were obtained forthe WO3 thin film annealed at 400C due to high sensor response to very low hydrogen concentrations(SR = 6.3 for 25 ppm H2) as well as short response and recovery times.Keywords: electronics, tungsten oxide, thin film, gas impulse magnetron sputtering, gas sensingproperties

The Effect of Hydrogen on Nonlinear Flame Saturation

Abstract We investigate the effect of increasing levels of hydrogen enrichment on the nonlinear response and saturation of premixed bluff-body stabilized methane/hydrogen flames submitted to acoustic forcing. The thermal power is kept approximately constant to preserve the nozzle velocity while increasing the flame speed through hydrogen enrichment. The flame describing function (FDF) is measured for a fixed frequency and three hydrogen–methane blends ranging from 10% to 50% by power, corresponding to 25% to 75% by volume. We show that when the flame is forced at the same frequency at similar power and bulk velocities, increasing levels of hydrogen enrichment increase the saturation amplitude of the flame. To provide insight into the flame dynamics responsible for the change in the global nonlinear response and saturation amplitude, the flames were investigated using high-speed imaging in combination with OH planar laser-induced fluorescence (OH-PLIF) at a range of forcing amplitudes. At lower hydrogen concentrations, the flame is stabilized along the inner shear layer and saturation in the heat release rate (HRR) occurs at lower forcing amplitudes due to large-scale flame–vortex interactions causing flame annihilation as observed in several previous studies. At increased levels of hydrogen enrichment, distinctly different flame dynamics are observed. In these cases, the flame accelerates and propagates across to the outer shear layer, which acts to suppress large-scale flame annihilation during roll-up of both the inner and outer shear layers. This results in a coherent increase in flame surface area with forcing amplitudes significantly increasing the saturation amplitude of the flame. These results show that high levels of hydrogen increase the amplitude response to acoustic forcing leading to higher saturation amplitudes. This suggests that substituting natural gas with hydrogen in gas turbines increases the risk of much higher limit-cycle amplitudes if self-excited instabilities occur.

Incorporation of indium into GaN layers in the context of MOVPE thermodynamics and growth – Ab initio studies

Indium incorporation on the GaN surface (0001) has been analyzed in the context of InGaN growth by Metal Organic Vapor Phase Epitaxy (MOVPE). To understand phenomena at the atomic level, calculations based on Density Functional Theory (DFT) and thermodynamic analysis of the surface processes have been performed. The considerations are limited to the terrace on GaN (0001) surface, covered fully by NH3/NH2 species. The ab initio results indicate that the adsorption energy strongly depends on the electronic properties of the surface. The adsorption energy varies from EadsDFT=-10.0eV for fully NH2 covered to EadsDFT=-3.0eV for mixed 0.69 NH2 + 0.31 NH3 covered surface. This change is related to Fermi level position moved from within valence band, across the bandgap, up to within conduction band. The shift in Fermi energy impacts the energy gained during adsorption due to electron occupation of surface states. Furthermore, a comprehensive thermodynamic analysis was conducted, revealing an additional, albeit smaller, contribution from the vibrational degrees of freedom to free energy. The combined effect of these factors leads to an increase in the equilibrium pressures of indium related to the increase in hydrogen pressure, which correlates with high coverage by ammonia molecules. The results demonstrate that the significant reduction in indium incorporation into InGaN layers during MOVPE growth under conditions of low hydrogen concentration in the vapor can be attributed to the influence of hydrogen on In adsorption processes.