Addition Of H2 Gas Research Articles

Hydrogen incorporation into solvents can improve the extraction of phenolics, flavonoids, anthocyanins, and antioxidants: A case-study using red beetroot

Different methods are used for extracting phytochemicals from plant produce. Some ‎methods require sophisticated and expensive instruments, while others need multiple steps ‎and specialist equipment, leading to an increase in energy, solvents, cost, and time. Here, the effect of incorporating hydrogen (H2) into solvents (that is water, ethanol, ‎methanol) on the extraction of flavonoids (TFC), phenolics (TPC), anthocyanins ‎‎(TAC), and antioxidants (DPPH and ABTS), as well as the extraction yield from red ‎beetroot, were evaluated. The biggest extraction yield was with the use of H2-rich ‎methanol (HRM) (24.32%). Incorporating H2 into water, ethanol, and methanol ‎led to a significant increase in TPC by 77.34%, 39.02% and 89.07%, in the TFC by ‎‎43.30%, 50.5% and 88.87%, in the TAC by 92.62%, 199.5% and 257.41%. DPPH ‎scavenging activity increased by 6.49%, 7.05% and 12.15%, and ABTS scavenging ‎activity by 3.93%, 9.82% and 15.05%, respectively. The extraction of individual ‎phenolic compounds, using various solvents, were different for each compound ‎investigated, with HPLC analysis showing that the levels of some phenolics increased ‎when H2 was incorporated into the solvents. ‎This method, i.e., addition of H2 gas, is ‎suggested as a relatively cheap and practical method for increasing the extraction of ‎phytochemicals using an eco-friendly method.

Effect of H2 addition during PECVD on the moisture barrier property and environmental stability of H:SiNx film

AbstractA hydrogenated silicon nitride (H:SiNx) film with enhanced moisture barrier property and environmental stability was developed using plasma‐enhanced chemical vapor deposition (PECVD) with the addition of H2 gas at 100°C. The moisture barrier property and film density of the 100‐nm‐thick H:SiNx film were ameliorated by increasing the H2 gas flow rate during PECVD. X‐ray photoelectron spectroscopy and Fourier‐transform infrared spectroscopy studies demonstrated that the improved performance was a result of an increase in the amount of Si–N bonds compared to hydrogen‐terminated bonds with an increase in the H2 gas flow rate. It is believed that H2 gas assisted the formation of aminosilane, which contributed to the condensation of silicon nitride by lowering the activation energy for radicalization reactions of silane and ammonia. After the 85°C/85% RH test, the optimized H:SiNx film maintained a water vapor transmission rate lower than 5 × 10−5 g/m2/day owing to the suppression of oxidation. The optimized H:SiNx film was rarely oxidized owing to the decrease in hydrogen‐terminated bonds and increase in the film density. The results indicated that the introduction of H2 gas during the PECVD process strengthened the environmental stability of the H:SiNx film.

Reversible dehydrogenation of a primary aryl borane.

The consecutive activation of B-H bonds in mesitylborane (H2BMes; Mes = 2,4,6-(CH3)3C6H2) by a 16-electron rhodium(i) monocarbonyl complex, (iPrNNN)Rh(CO) (1-CO; iPrNNN = 2,5-[iPr2P[double bond, length as m-dash]N(4-iPrC6H4)]2N(C4H2)-) is described. Dehydrogenative extrusion of the {BMes} fragment led to the isolation of (iPrNNN)(CO)RhBMes (1-BMes). Addition of H2 gas to 1-BMes regenerated 1-CO and H2BMes, highlighting the ability of 1-CO to facilitate interconversion of {BMes} with dihydrogen. Reactivity studies revealed that 1-BMes promotes formal group transfer and that {BAr} fragments accessed by dehydrogenation are reactive entities.

Pyridine(diimine) Chelate Hydrogenation in a Molybdenum Nitrido Ethylene Complex

Addition of H2 gas to the aryl-substituted pyridine(diimine) molybdenum nitride (iPrPDI)Mo(N)(C2H4) ([1-(N)(η2-C2H4)]; iPrPDI = 2,6-(2,6-iPr2-C6H3N═CMe)2C5H3N) in the presence of the rhodium hydride precatalyst (η5-C5Me5)(py-Ph)Rh(H) ([Rh–H]; py-Ph = 2-phenylpyridine) resulted in partial hydrogenation of the central pyridine of the iPrPDI chelate to yield (iPrTHPDI)Mo(N)(C2H4) ([2-(N)(η2-C2H4)]; iPrTHPDI = 2,6-(2,6-iPr2-C6H3N═CMe)2C5H6N). The product, [2-(N)(η2-C2H4)], was structurally and spectroscopically characterized, and its electronic structure was examined by density functional theory (DFT). The stepwise addition of H atoms from [Rh–H] to [1-(N)(η2-C2H4)] was computed to be thermodynamically viable by DFT.

In-Situ Studies of Carbon Removal from Ni-YSZ Anodes Using Mixtures of O2 and H2

There is interest in understanding the chemical mechanisms in order to improve approaches for reforming fuels and regenerating components in solid oxide fuel cells. Chemical and electrochemical oxidative removal of carbon from Ni-YSZ anodes is studied using a suite of experimental techniques. After carbon is deposited on the anodes during methane exposure, it is removed with a series of the oxidizing mixtures containing a fixed O2 concentration and varying H2 concentrations. The CO and CO2 produced are monitored in real time using IR emission and mass spectrometry. Concurrently, near IR imaging of the anode is employed to monitor the surface temperature and electrochemistry to track the open circuit potential of the cell. The data demonstrate monotonically increasing amount of CO and decreasing amount of CO2 with the increasing H2 concentration. In addition, a control experiment of carbon removal with H2O yields relative amounts of evolved CO and CO2 close to those observed with the 1:2 O2:H2 mixture. The results implicate atomic O and -OH as primary chemical removal agents, the latter being effective at oxidizing carbon to CO and the former at oxidizing CO to CO2. In a separate experiment, electrochemical removal of the pre-formed carbon via cell polarization indicates an efficient oxidation of electrochemically accessible carbon to CO and a slow oxidation of CO to CO2. Addition of H2 gas during the polarization removal experiments leads to electrochemical generation of water inside the anode, which further accelerates oxidation of carbon. Thus, the present work clarifies mechanisms of carbon removal from the anodes of SOFCs.

A 490 W transversely excited atmospheric CO2 spark gap laser with added H2

In this paper we present a new design for a high pulse repetition rate transversely excited atmospheric CO2 laser with ultraviolet pre-ionization. A new method of fast thyristor capacitor charging and discharging by a spark gap is used. The effect of H2 gas addition on the output and stability of a transversely excited atmospheric laser operating with a basic mixture of CO2, N2 and He is investigated. The output power was increased by adding H2 to the gas mixture ratio of CO2:N2:He:H2 = 1:1:8:0.5 at total pressure of 850 mbar. An average power of 490 W at 110 Hz with 4.5 J per pulse was obtained. The laser efficiency was 11.2% and oxygen gas was used in the spark gap for electron capture to reduce the recovery time and increase the repetition rate.

Synthesis of Iron Hydride Complexes Relevant to Hydrogen Isotope Exchange in Pharmaceuticals

Addition of H2 gas to the bis(arylimidazolin-2-ylidene)pyridine iron bis(dinitrogen) complex (H4-iPrCNC)Fe(N2)2 resulted in facile oxidative addition of the H–H bond to yield a mixture of (H4-iPrCNC)FeH4 and trans-(H4-iPrCNC)FeH2(N2), depending on the partial pressures of H2 and N2. Both iron hydride complexes were characterized by X-ray diffraction and proved relevant to the catalytic hydrogen isotope exchange of arene C(sp2)–H bonds. Activation of the benzene-d6 solvent at ambient temperature produced deuterated isotologues of both compounds that exhibit large isotopic perturbation of resonances in the hydride signals.

Effect of hydrogen gas addition on combustion characteristics of pulverized coal

A promising approach to decrease CO2 emissions from blast furnaces during ironmaking is to blow a reducing gas containing hydrogen into blast furnaces from their tuyeres. However, the combustion behavior of pulverized coal in the presence of a hydrogen-containing gas has not been elucidated. In this work, the combustion experiments of pulverized coal using a drop tube furnace were carried out to investigate the effect of H2 gas addition on the combustibility of pulverized coal. The combustion ratio of char particles in the presence of H2 gas (when introduced at a flow rate of 0.10L/min) was larger than that in the absence of H2 gas. This is because of the enhanced release of volatile matter from coal and the combustion of char due to an increase in the temperature of the coal particles, which was caused by the drastic combustion of H2 gas. The combustion ratio of char particles when H2 gas was added at flow rates higher than 0.21L/min was considerably smaller than that obtained when H2 gas was not added. It was found that the combustibility of coal was enhanced when an optimum H2 gas flow rate was used.

Reduction of Panzhihua titanium-bearing oxidized pellets by CO-N2-H2 gas

The effect of H2 gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N2-H2 gas mixtures in a vertical electric resistance furnace. The morphology and phase transformation of reduced samples obtained were detected by scanning electron microscopy, energy disperse spectroscopy analysis and X-ray diffractometry respectively. The results show that increasing H2 content will enhance the initial stage of reduction rate apparently. There are two reasons responsible for this effect, one is that H2 accelerates the chemical reaction, and the other is that the addition of H2 gas can improve the porosity of pellet intensively. It is noteworthy that this effect is more obvious when the reduction temperature reaches 1473 K with sticking phenomenon happening. There are no crystalline phases which can be found such as ulvospinle, ilmenite, ferrous-pseudobrookite and any titanium oxide except titanomagnetite (TTM). The reduction progress is suggested as follows: 1) Fe2O3→Fe3O4→FeO→Fe; 2) Fe2TiO5→Fe2TiO4+Fe3O4→TTM. Element Al migrates and gets enriched in high titanium content iron ores, and eventually Al to Ti molar ratio is 1:3. Al is likely to dissolve in titanium iron oxides to form a kind of composite iron compound, which results in the restrain of reduction.

Vibration, noise and exhaust emissions analyses of an unmodified compression ignition engine fuelled with low sulphur diesel and biodiesel blends with hydrogen addition

Depletion thread of fossil fuels and emission regularities of countries enforce researchers to use alternative resources in diesel engines. Hydrogen and biodiesel are one of the most important alternative fuels. Therefore, all effect of them must be investigated on diesel engine. In this study, experimental investigation was conducted on an unmodified four-stroke four-cylinder compression ignition engine, in order to comprehend its noise and vibration characteristics when the engine was fuelled with sunflower, canola, and corn biodiesel blends with %20 and %40 volume ratio while H2 injected through inlet manifold with 3 l/min and 6 l/min flow rates. The results revealed that changes of sound pressure level with H2 addition depended on engine speed whereas vibration acceleration was decreased with addition of gas at all engine speeds. Furthermore, in this paper exhaust emission characteristic of the engine when it was fuelled with sunflower, canola, and corn biodiesel blends and H2 gas addition was presented.

Process controllability of inductively coupled plasma-enhanced reactive sputter deposition for the fabrication of amorphous InGaZnOx channel thin-film transistors

The process controllability of inductively coupled plasma-enhanced reactive sputter deposition for the fabrication of amorphous InGaZnOx (a-IGZO) channel thin-film transistors (TFTs) was investigated. a-IGZO film deposition with the addition of H2 gas was performed using a plasma-assisted reactive sputtering system to control the oxidation process during a-IGZO film formation by balancing the oxidation and reduction reactions. Optical emission spectroscopy measurements indicate the possibility for the oxidation reaction to be inhibited by a decrease in the density of oxygen atoms and the reduction effect of hydrogen during a-IGZO film deposition due to the addition of H2 gas. The characteristics of TFTs fabricated using a-IGZO films deposited with a plasma-enhanced magnetron sputtering deposition system were investigated. The results indicate the possibility of expanding the process window by controlling the balance between oxidation and reduction with the addition of H2 gas. TFTs with a-IGZO films that were deposited with the addition of H2 gas exhibited good performance with a field-effect mobility (μFE) of 15.3 cm2 V−1 s−1 and a subthreshold gate voltage swing (S) of 0.48 V decade−1.

Highly Conductive Cu Thin Film Deposition on Polyimide by RF‐Driven Atmospheric Pressure Plasma Jets under Nitrogen Atmosphere

The use of Ar/H2 atmospheric pressure plasma jets driven by a 13.56 MHz RF wave source with a Cu inner conductor was investigated for the deposition of highly conductive Cu thin films on polyimide substrates. It was found that the intensities of the Cu atom emission line were significantly increased by the addition of H2 gas to the Ar plasmas. Secondary emission microscopy analysis indicated that the Cu films exhibited agglomerated structures with grains of several microns, which were larger than those produced using Ar plasma jets. It was found that the conductivity of Cu thin films prepared in nitrogen was 106 times higher than that of films produced using Ar/H2 plasma jets with 10 sccm H2, and 4 times higher than that for films produced using identical Ar/H2 plasma jets in air.

Characteristics of high-purity Cu thin films deposited on polyimide by radio-frequency Ar/H2 atmospheric-pressure plasma jet

With a view to fabricating future flexible electronic devices, an atmospheric-pressure plasma jet driven by 13.56 MHz radio-frequency power is developed for depositing Cu thin films on polyimide, where a Cu wire inserted inside the quartz tube was used as the evaporation source. A polyimide substrate is placed on a water-cooled copper heat sink to prevent it from being thermally damaged. With the aim of preventing oxidation of the deposited Cu film, we investigated the effect of adding H2 to Ar plasma on film characteristics. Theoretical fitting of the OH emission line in OES spectrum revealed that adding H2 gas significantly increased the rotational temperature roughly from 800 to 1500 K. The LMM Auger spectroscopy analysis revealed that higher-purity Cu films were synthesized on polyimide by adding hydrogen gas. A possible explanation for the enhancement in the Cu film deposition rate and improvement of purity of Cu films by H2 gas addition is that atomic hydrogen produced by the plasma plays important roles in heating the gas to promote the evaporation of Cu atoms from the Cu wire and removing oxygen from copper oxide components via reduction reaction.

Effects of H2 gas addition into process and H ion implantation on the microstructure of hydrogenated amorphous carbon films prepared by bipolar-type plasma based ion implantation

Hydrogenated amorphous carbon films are deposited on Si(100) and SiO2 glass substrates by a bipolar-type plasma based ion implantation system. The films are prepared using toluene gas at a constant flow rate of 2sccm. The effects of H2 gas addition during deposition on the microstructure of the films are examined by electrical conductivity measurements, Raman spectroscopy, elastic recoil detection analysis (ERDA) and optical spectroscopy. In addition, H implantation is also carried out using H2 plasma discharge. Thickness of the films is approximately 60nm for all samples. It is found that electrical conductivity slightly increases with increasing additive H2 flow rate. However, the conductivity drastically decreases after H implantation. Raman analysis reveals that H2 gas addition slightly causes the film graphitization, but the H implantation does it amorphization. The results of ERDA show that the H concentration in the films slightly decreases with increasing H2 gas addition, but increases by H implantation. In spite of H2 gas addition, the optical band gap is not changed and kept approximately 0.7eV. However, H implantation makes it increase up to approximately 1.0eV.

Decaying of Nitrogen Second Positive System by Addition of H<sub>2</sub> Gas in Air DB Discharge

Effects of addition of H2 gas in air DB discharge on its optical and electrical characteristics have been studied. Optical emission spectroscopy is used to investigate the effect of hydrogen admixing on the emission intensity of the nitrogen second positive systems (300 - 420 nm) and the relative population density of states. An obvious decaying of the emission intensity of the nitrogen second positive bands with the introduction of H2 has been observed. It has been concluded that quenching of the nitrogen excited state is the responsible reason of this decaying. Mechanisms of excitation and ionization processes of nitrogen molecules in this mixture have been studied. Processes which are responsible for the decaying of the population density of have been reported. Addition of H2 to air improves the electrical characteristics of the DB discharge. An abrupt increasing in the electron density, reached about thirty fold at H2 flow rate of 3 L/min, as a result of increasing the ionization processes has been reported. The breakdown voltage of the discharge decreased from 1.87 kV to about 1.25 kV by the addition of H2 at flow rate of 3 L/min.

수소 가스를 첨가한 글라이딩 아크 플라즈마의 과불화화합물(PFCs) 가스 분해 특성

Perfluorocompounds (PFCs) gases were decomposed by gliding arc plasma generated by AC pulse power. gas of 10 LPM flow rate and gas of 0.5 LPM were introduced into the gliding arc plasma generated between a pair of electrodes with SUS 303 material, and the PFCs gases were injected in the plasma and thereby were decomposed. The PFCs gas-decomposition-characteristics through the gliding arc plasma were analyzed by FT-IR, where pure and -added environment were used to generate the gliding arc plasma. The PFCs gas-decomposition-properties were changed by electric power for gliding arc plasma generation and the H2 gas addition was effective to enhance the PFCs decomposition rate.

Surface reactivity of molybdenum thin films exposed to (Ar–N2–H2) expanding microwave plasma at low temperature: influence of the addition of H2 gas in the plasma

The rapid transfer of a large amount of nitrogen into the surface layers followed by diffusion into the inner layers occurs in thin molybdenum films exposed to expanding microwave plasma using (Ar–35%N2) and (Ar–25%N2–30%H2) gas mixtures. The nitrogen transfer into the surface layers nearly correlates to a Gaussian distribution law, which is explained by the formation of a large number of defects at the film surface in which nitrogen piles up before diffusing into the inner metal layers. Such an effect could be induced by the impinging energetic plasma species as ions, NHx < 3 radicals. The diffusion part is successfully fitted to Fick's second law by introducing diffusion coefficients of about (5–7) × 10−14 cm2 s−1 at 673 K. These values are lower than the diffusion coefficient calculated for a solid solution of nitrogen in molybdenum which is equal to about 4 × 10−13 cm2 s−1. A surprisingly high diffusion coefficient of about 3 × 10−13 cm2 s−1 is found for the molybdenum film exposed to (Ar–25%N2–30%H2) plasma at room temperature. These results highlight the role of plasma hydrogen species on the enhancement of the metal surface reactivity and nitrogen diffusion into the inner metal layers. A modification of the morphology of the film surface exposed to hydrogen species is also seen.The values of electron densities measured in the various (Ar–N2–H2) gas mixtures are consistent with the formation of expanded plasma far from the centre of the discharge, apart from(Ar–30%N2–12%H2) where the plasma expansion is very low. At a distance of 10.5 cm from the centre of the discharge, the electron density is equal to about 1.66 × 1017 m−3 and 1.16 × 1017 m−3 for (Ar–25%N2–30%H2) and (Ar–35%N2) gas mixtures, respectively.

Role of Hydrogen in Dry Etching of Silicon Carbide Using Inductively and Capacitively Coupled Plasma

We investigated the etching mechanism of SiC using inductively and capacitively coupled plasma with CHF3 and SF6 gases. We discussed the effects of O2 and H2 gases on etching properties. By optimizing the conditions of H2 flow rate, we could confirm the improvement in etching rates. Surface roughness was also improved by the optimum addition of H2 gas. Analysis by XPS revealed that a fluorocarbon film was formed on the surface after etching with SF6 gas. Surface fluoride atomic concentration was reduced from 28 to 8 at.% by the addition of H2 gas. A H2 annealing suppressed the fluoride concentration of surface to less than 3 at.%. This processing technique is very effective for the fabrication of SiC devices.

The Properties of Low Hydrogen Content α-Si Thin Film Using DC-Bias Enhanced or Addition of H2 Gas in Mesh-type PECVD System

The Properties of Low Hydrogen Content α-Si Thin Film Using DC-Bias Enhanced or Addition of H2 Gas in Mesh-type PECVD System

Synthesis of large area aligned carbon nanotube arrays from C2H2–H2 mixture by rf plasma-enhanced chemical vapor deposition

Large area aligned carbon nanotube (CNT) arrays have been successfully synthesized from C2H2 and H2 mixture by rf plasma-enhanced chemical vapor deposition (without hot filament) on iron-coated silicon substrates. H2 plasma (not H2 gas) was confirmed to play the role of reducing iron oxide to metallic iron and promoting the formation of evenly separated particles, as well as being the primary factor in synthesizing aligned CNTs. The addition of H2 gas with no plasma during the growth resulted in randomly oriented CNTs. Meanwhile, without the addition of H2, the C2H2 plasma resulted in the growth of very fine worm-like carbon fibers. Using substrates with a thicker catalyst layer (&amp;gt;90 nm) reduced the CNT density significantly.