Generated Hydrogen Gas Research Articles

The Impact of Hydrogen Gas Evolution on Blister Formation in Electroless Cu Films

Electroless Cu plating is a key process to provide electrically conductive layers on insulating substrates for the subsequent Cu electroplating of printed-circuit boards (PCBs). Recently introduced substrate materials are prone to spontaneous delamination failure (blistering) of the electroless layer during deposition. A higher Ni content in electroless Cu baths prevents delamination failure by increasing the internal tensile stress in the Cu layer. This effect is achieved by suppressing Cu self-diffusion through the incorporation of small amounts of Ni in the grain boundaries and the grain boundary junctions. Whether the hydrogen gas evolved inevitably during electroless Cu deposition and potentially trapped in the deposit may cause blistering is still under debate. Here we test this hypothesis by quantifying the generated hydrogen gas volume during Cu deposition in baths with Ni concentrations between 0 and 1000 ppm, and observing the rate of blister formation in the deposit. We find a constant molar ratio of 0.65 ± 0.05 mol H2/mol Cu independent of the Ni content in the bath, in contrast to a systematic and substantial change of the blister probability. From this lack of a correlation between the blister rate and hydrogen evolution, we rule out hydrogen evolution as a determining factor for blister formation.

Self-powered macroscopic Brownian motion of spontaneously running liquid metal motors

We disclosed the interiorly driven macroscopic Brownian motion behavior of self-powered liquid metal motors. Such tiny motors in millimeter scale move randomly at a velocity magnitude of centimeters per second in aqueous alkaline solution, well resembling the classical Brownian motion. However, unlike the existing phenomena, where the particle motions were caused by collisions from the surrounding molecules, the current random liquid metal motions are internally enabled and self-powered, along with the colliding among neighboring motors, the substrate and the surrounding electrolyte molecules. Through uniformly dissolving only 1% (mass percentage) Al into GaIn10, many tiny motors can be quickly fabricated and activated to take the Brownian-like random motions. Further, we introduced an experimental approach of using optical image contrast, which works just like the Wilson cloud chamber, to distinctively indicate the motor trajectory resulted from the generated hydrogen gas stream. A series of unusual complicated multi-phase fluid mechanics phenomena were observed. It was also identified that the main driving factor of the motors comes from the H2 bubbles generated at the bottom of these tiny motors, which is different from the large size self-fueled liquid metal machine. Several typical mechanisms for such unconventional Brownian-like motion phenomena were preliminarily interpreted.

The Impact of Hydrogen Gas Evolution on Blister Formation in Electroless Copper Films

Electroless copper plating is a key process to provide electrically conductive layers on insulating substrates for the subsequent copper electroplating of printed circuit boards (PCBs). Recently introduced substrate materials are prone to spontaneous delamination failure (blistering) of the electroless layer during deposi-tion. A higher nickel content in electroless copper baths prevents delamination failure by increasing the internal tensile stress in the copper layer. This effect is achieved by suppressing copper self-diffusion through the incorporation of small amounts of nickel in the grain boundaries and the grain boundary junc-tions. Whether the hydrogen gas that evolves inevitably during electroless copper deposition, and that is potentially trapped in the deposit may cause blistering is still under debate. Here we test this hypothesis by quantifying the generated hydrogen gas volume during copper deposition in baths with nickel concentra-tions between 0 and 1000 ppm, and observing the rate of blister formation in the deposit. We find a con-stant molar ratio of 0.65±0.05 mol H2/mol Cu independent of the nickel content in the bath, in contrast to a systematic and substantial change of the blister probability. From this lack of a correlation between the blister rate and hydrogen evolution, we rule out hydrogen evolution as a determining factor for blister for-mation.

Kinetic Study of Hydrogen Generation from the Hydrolysis of Alkaline NaBH4 over Ru/MMT: an Insight on the Effect of Catalyst Amount

An efficient and cheap catalyst, montmorillonite supported Ru nanoclusters (Ru/MMT) were successfully prepared and explored for the hydrogen generation from alkaline NaBH4 solution. The catalytic behavior and the kinetics of Ru/MMT catalyzed hydrolysis of alkaline NaBH4 was studied detailedly by measuring the volume of generated hydrogen gas varying catalyst concentration and temperature. The relationship between the activation energy (Ea) of NaBH4 hydrolysis reaction and Ru/MMT amount was constructed, and the minimum value was determined to be 49.6 kJ/mol, which was lower than the most reported Ru-based supported catalysts that have been reported in the open literatures. The higher catalytic activity of Ru/MMT was due to the more open frame of montmorillonite than the other inorganic supporters, which decreases the substrate inhibition in catalytic hydrolysis of NaBH4.

Photoelectrolysis of Water in Tj-a-Si Solar Cell Biased CM-n-TiO2││Pt and in Monolithic Self-Driven n-TiO2 - Mn2O3 Coated Tj-a-Si││Pt Photoelectrochemical Cells

Carbon modified (CM)-n-TiO2 thin film was synthesized and optimized by flame oxidation method at high temperature of 825{degree sign}C, and 16 min heating time. The natural gas and oxygen flow rates of 3.32 L/min and 2.23 L/min were found optimum to incorporate the appropriate amounts of carbon concentration in the bulk and on the surface of the CM-n-TiO2 thin films. TJ-a-Si solar cell biased CM-n-TiO2│2.5 M KOH │Pt PEC generated hydrogen gas of 25.0 L m-2 h-1 and a photoconversion efficiency of 5.45 % under the solar simulated light illumination of 1 sun. Importantly, the Tj-a-Si solar cell biased dark water electrolysis cell of Pt│2.5 M KOH │Pt in did not show any measurable H2 gas production. The monolithic Self-Driven n-TiO2 -Mn2O3 coated Tj-a-Si│2.5 M KOH │Pt PEC generated hydrogen gas of 15.63 L m-2 h-1 and a photoconversion efficiency of 4.16 %. This PEC was found to last more than 5 hours (compared to maximum 5 min life time for uncoated Tj-a-Si│2.5 M KOH │Pt PEC). This limited stability for 5 hours was attributed to presence of some pin-holes on n-TiO2-Mn2O3 coated Tj-a-Si solar cell surface.

核燃料施設の事故影響評価手法に関する調査（ＩＩＩ）放射線分解水素爆発事象の事故影響評価手法に関する基礎的データ

A special committee on “Research on the analysis methods for accident consequence of nuclear fuel facilities (NFFs)” was organized by the Atomic Energy Society of Japan (AESJ) under the entrustment of Japan Atomic Energy Agency (JAEA). The committee aims to research on the state-of-the-art consequence analysis method for Probabilistic Safety Assessment (PSA) of NFFs, such as fuel reprocessing and fuel fabrication facilities. The objective of this research is to obtain the useful information related to the establishment of quantitative performance objectives and to risk-informed regulation through qualifying issues needed to be resolved for applying PSA to NFFs. The research activities of the committee were mainly focused on the analysis method of consequences for postulated accidents with potentially large consequences in NFFs, e.g., events of criticality, spill of molten glass, hydrogen explosion, boiling of radioactive solution, and fire (including rapid decomposition of TBP complexes), resulting in the release of radioactive materials into the environment. The results of the research were summarized in a series of six reports, which consist of a review report and five technical ones. In this technical report, the research results about basic experimental data related to the consequence of the radiolytically generated hydrogen gas explosion postulated in the radioactive solution reserve tank caused by the loss of dilution air supply were summarized.

Correlation between corrosion rate and AE signal in an acidic environment for mild steel

The AE method is an effective technique for inspecting corrosion damage of mild steel, such as tank bottom floors. However, the correlation between AE signals and corrosion behaviour for mild steel has not yet been fully clarified. In the present study, the authors considered that the corrosion regions of bottom floors become a strong acid environment by Cl −, as reported in a previous study. Thus, the polarization resistance for the test pieces of mild steel was measured with an AC impedance method under a strong acid environment. It was clear that the polarization resistance indicated the corrosion rate for a test piece of mild steel in the experiments. While measuring the AE signals, the corrosion rate was monitored with a test piece. As a result, the AE signal showed good correlation with the corrosion rates of the test pieces. The corrosion behaviour of the test pieces was then discussed with the corrosion potential measured during the experiments. Furthermore, the cathode current was changed to control the generated hydrogen gas volume. The volume of the hydrogen gas generated from the cathode reaction was correlated to the AE signals.

Inhibition of aluminium corrosion in alkaline solutions using natural compound

Inhibition of aluminium corrosion in 2 M sodium hydroxide solution in the presence and absence of 0.5 M NaCl using damsissa ( Ambrosia maritime, L.) extract has been studied employing different chemical and electrochemical techniques. Chemical gasometry technique showed that addition of chloride ions or damsissa extract to sodium hydroxide solution decreases the volume of the hydrogen gas evolved. Potentiodynamic results manifested that chloride ion retard the anodic dissolution of aluminium, below the pitting potential, in sodium hydroxide solution. Damsissa extract, in presence or absence of chloride ion, influenced both the anodic dissolution of aluminium and the generated hydrogen gas at the cathode indicating that the extract behaved as mixed-type inhibitor. The decrease in the observed limiting current with increasing damsissa extract concentration indicated that the anodic process is controlled by diffusion. Nyquist plots present two capacitive semicircles at higher and lower frequencies separated by an inductive loop at intermediate frequencies. The inductive loops were clarified by the occurrence of adsorbed intermediates on the surface. A proposed equivalent circuit was used to analyze the impedance spectra for aluminium in alkaline solutions. The results showed that the damsissa extract could serve as an effective inhibitor for the corrosion of aluminium in alkaline solutions. The impedance measurements verified the remarkable stability of the extracts during storage up to 35 days. Damsissa extract was found more effective in presence of chloride ions than in its absence. Inhibition was found to increase with increasing concentration of the extract but decreases with increasing temperature. The associated activation parameters were determined and discussed.

Dominant Factor for the Occurrence of a Steam Explosion

For the study of a steam explosion phenomenon in a nuclear reactor, prototypic corium, a mixture of UO2 and ZrO2 was melted in a cold crucible by applying an induction heating technique. The molten corium was then poured into cold water. It was fragmented into very small particles, so called debris, which enables a very rapid heat transfer to the water. Some cases led to steam explosions by thermal expansion of the water. After the tests, all the debris particles were dried and classified by their size. From the analysis by using EPMA, it was shown that the particles generated by a steam explosion had fine and irregular forms. It is known that real corium (including UO2) hardly leads to a steam explosion, different from pure ZrO2 or metal. A reason for this was previously suggested in that the corium generated hydrogen gas during melt-water interaction, and it enclosed the melt drops to prevent a direct contact of the corium and water. In order to confirm this fact, the debris particles were analyzed with ICP-AES for their typical element contents, EPMA for the homogeneity of the solid solution, XRD for the chemical compounds, and TGA and hydrogen reduction analysis for the percentage of the debris oxidation and reduction. These analyses showed that hydrogen was not directly related to steam explosion. Meanwhile, the material characteristics of the corium compositions are newly suggested to be the most probable reason for the occurrence of a steam explosion so far.

Energy release characteristics of the nanoscale aluminum-tungsten oxide hydrate metastable intermolecular composite

Tungsten oxides are of interest as an oxidant for metals in metastable intermolecular composites (MICs), a reactive nanoscale powder useful for such applications as electric matches and gun primers. Smaller particles typically lead to fast reaction rates in this class of energetic material, and we have synthesized nanoscale WO3∙H2O using wet chemistry. Analysis by electron microscopy and small angle x-ray scattering revealed an approximately 100-nm-wide by7-nm-thick platelet morphology. X-ray diffraction verified the orthorhombic structure and composition of the hydrate. A MIC material was formulated using 44nm Al as the fuel. Performance was measured using a pressure cell where total enthalpy change and energy release rate was measured. This report includes the thermodynamic analysis of the pressure cell (calorimetry) that allows the determination of these metrics. Accuracy of the technique is discussed. Performance of the hydrate was found to significantly exceed that of MIC formulated with dehydrated tungsten oxide for one formulation, having an energy release of approximately 1.8MJ∕kg at a rate of approximately 215GW∕m2, compared to around 1.1MJ∕kg at a rate of around 130GW∕m2 for the dehydrated formulation. The data show that the enhanced behavior of the hydrated MIC formulation resulted from the reaction of aluminum with the interstitially bound water, which had additional energy release and generated hydrogen gas.

化成処理によるマグネシウム上への環境イノベーション皮膜の合成

Titanium dioxide (TiO2) coatings were prepared by chemical conversion treatment of magnesium in (NH4)2[TiO(C2O4)2] with H2O2, then, anatase type TiO2 coatings were prepared by sintering. To identify the coating structure, coating analysis was carried out using an infrared absorption spectrum analyzer. Based on the infrared absorption results, a component of the coating was found in the hydrolysis product of peroxo-titanium compound. Furthermore, the coating analysis was carried out using X-ray diffractometry (XRD), and non-sintered coating was amorphous; however, the coating sintered at more than 573 K was anatase-type titanium dioxide. In the forming process of the conversion treatment in (NH4)2[TiO(C2O4)2] with H2O2, first, the magnesium was dissolved to H+ in the bath and then, hydrogen ions on the magnesium surface were consumed to generated hydrogen gas. Thus, the pH of the interface became alkali. The hydrolysis of the peroxo-titanium compound was deposited on the magnesium because pH increased on the surface. From the XPS results and the TG-DTA results, a component of the coating is a hydrolyzation product of a peroxo-titanium compound and Mg(OH)2. Because Mg(OH)2 is generates in pH more than 11, it is considered that the pH on the magnesium surface is more than 11. The coating sintered at 573 K had the highest photocatalytic activity. The photocatalytic activity of the coating sintered at 623 K was lower than the coating heated at 573 K, which is attributed to growth of TiO2 particle. This forming process of the coating is low cost because of the useless electrolytic decomposition process and increasing the speed of the treatment. It is possible to treat complicated form of the substrate metal, so this method can be expected to use in various fields. Therefore this method is expected to practical use for environmental purification.

Electrochemically Controlled Formation and Growth of Hydrogen Nanobubbles

Electrogenerated microscale bubbles that are confined at the electrode surface have already been extensively studied because of their significant influence on electrochemistry. In contrast, as far as we know, whether nanoscale bubbles exist on the electrode surface has not been experimentally confirmed yet. Here, we report the observation of electrochemically controlled formation and growth of hydrogen nanobubbles on bare highly oriented pyrolytic graphite (HOPG) surface via in-situ tapping mode atomic force microscopy (TMAFM). By using TMAFM imaging, we observed that electrochemically generated hydrogen gas led to the formation of nanobubbles at the HOPG surface. We then employed a combination of techniques, including phase imaging, ex-situ degassing, and tip perturbation, to confirm the gas origin of such observed nanobubbles. We further demonstrated that the formation and growth of nanobubbles could be well controlled by tuning either the applied voltage or the reaction time. Remarkably, we could also monitor the evolution process of nanobubbles, that is, formation, growth, coalescence, as well as the eventual release of merged microbubbles from the HOPG surface.

Calcium-promoted Catalytic Degradation of PCDDs, PCDFs, and Coplanar PCBs under a Mild Wet Process

The authors achieved highly efficient degradation of polychlorinated aromatic compounds, including polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like compounds such as coplanar polychlorinated biphenyls (co-PCBs), which are known as persistent organic pollutants. Degradation was accomplished in 24 h through a simple stirring operation using safe and high workability metallic calcium, which acts as both a scavenger and a reducing agent, and Rh/C catalyst in an alcohol solution under mild conditions in a sealed tube at 25 degrees C without a temperature increase within 0.15 MPa of increasing internal pressure during the reaction. In this system, reductive dechlorination by metallic calcium and catalytic reduction by Rh/C and generated hydrogen gas, without any external addition of hydrogen, exert a synergistic effect on the degradation of chlorinated compounds. Alcohol was used as a proton source and hydrogen, which was generated by a side reaction, causes an increase in the activity of Rh/C catalyst. Through the degradation of 4-chloroanisole in ethyl alcohol, anisole and cyclohexyl methyl ether were obtained in good conversions. Using ethyl alcohol as a solvent, treatment of dioxins and co-PCBs in a solution was markedly effective for degradation to reduce 2806 pg TEQ/ml of initial concentration to 31.8 pg TEQ/ml; its yield was 98.5%. Moreover, degradation in methyl alcohol took place in a 99.3% yield. That concentration ultimately reached 20.3 pg TEQ/ml under a mild wet process. All congeners of dioxins and co-PCBs were degraded in high conversions. In this degradation, lower aliphatic alcohol, such as methyl alcohol, is effective for making a new calcium surface as compared to alcohol with more methylene chains. In addition, it seemed that a higher pressure of hydrogen was easily generated in methyl alcohol, and then catalytic degradation was effectivley influenced.

Synthetic Process of Environmentally-Friendly TiO<SUB>2</SUB> Coating on Magnesium by Chemical Conversion Treatment

Titanium dioxide (TiO2) coatings were prepared by chemical conversion treatment of magnesium in (NH4)2[TiO(C2O4)2] with H2O2, then, anatase type TiO2 coatings were prepared by sintering. To identify the coating structure, coating analysis was carried out using an infrared absorption spectrum analyzer. Based on the infrared absorption results, a component of the coating was found in the hydrolysis product of peroxo-titanium compound. Furthermore, the coating analysis was carried out using X-ray diffractometry (XRD), and non-sintered coating was amorphous; however, the coating sintered at more than 573 K was anatase-type titanium dioxide. In the forming process of the conversion treatment in (NH4)2[TiO(C2O4)2] with H2O2, first, magnesium was dissolved because H þ in the bath reacted with the magnesium. Hydrogen ions on the magnesium surface were consumed to generated hydrogen gas. Thus, the pH of the interface became alkali. The hydrolysis of the peroxo-titanium compound was deposited on the magnesium because pH increased on the surface. From the XPS results and the TG-DTA results, a component of the coating is a hydrolyzation product of a peroxo-titanium compound and Mg(OH)2. Because Mg(OH)2 is generates in pH more than 11, it is considered that the pH on the magnesium surface is more than 11. The coating sintered at 573 K had the highest photocatalytic activity. The photocatalytic activity of the coating sintered at 623 K was lower than the coating heated at 573 K, which is attributed to growth of TiO2 particle. This forming process of the coating is low cost because of the useless electrolytic decomposition process and increasing the speed of the treatment. It is possible to treat complicated form of the substrate metal, so this method can be expected to use in various fields. Therefore this method is expected to practical use for environmental purification. [doi:10.2320/matertrans.47.2335]

Removal of nitrate in aquaria by means of electrochemically generated hydrogen gas as electron donor for biological denitrification

A hydrogenotrophic denitrification reactor was designed for the removal of nitrate from aquaria. An average hydrogen gas transfer up to 130 mg per day from the gas to the water phase was accomplished by recirculating the water from the denitrification reactor over a separate trickling filter column with a volume of 1.3 l. During batch experiments removal rates up to 36 mg N/l reactor per day were recorded at a hydraulic residence time of 12 h. To avoid the need for storage of large volumes of hydrogen gas in aquarium or aquaculture applications, an electrochemical cell was used to generate hydrogen gas. During a 7 day aquarium test, a nitrate removal rate up to 18.5 mg N/l reactor per day was recorded at an influent NO 3 −–N concentration of 20 mg/l.

Denitrification and neutralization treatment by direct feeding of an acidic wastewater containing copper ion and high-strength nitrate to a bio-electrochemical reactor process

The feasibility of the direct denitrification treatment of copper metal pickling wastewater by using a bio-electrochemical reactor process was investigated experimentally. Carbon electrodes were installed in the reactor as the anode and cathode and denitrifying microorganisms were fixed on the surface of the cathode. The reactor was continuously operated by applying an electric current and feeding acetate. In this reactor, copper ion removal and denitrification proceeded simultaneously and the pH value of the treated water was increased almost to neutral. The electric current that passed through the cathode contributed to the removal of the copper ion and the generation of hydrogen gas. The generated hydrogen gas as well as the added acetate was effectively utilized for denitrification. A theoretical evaluation of pH in the effluent suggested that the pH increase was mainly caused by the generation of hydroxyl ion during denitrification. In addition, the inorganic carbon species generated during denitrification with acetate and by the electrochemical oxidation of anodic carbon acted as a buffer to minimize a further increase of pH at higher nitrate removal efficiencies. These results demonstrated that copper ion removal, denitrification and neutralization could be achieved simultaneously by using a single bioelectrochemical reactor.

酸化銀電池の電解液漏洩封止に関する研究 （第４報） 水素ガス発生抑止による封止法の開発

Mixture of epoxy resin and asphalt was used as sealant, which existed between the gasket and anode can, in the silver oxide battery. Best mixing ratio among epoxy resin, hardener and asphalt was proposed, and two reasons that the mixture of epoxy resin and asphalt show good seal characteristics are shown in this experiment. One of the reasons is that the mixture worked as soft material between gasket and can to decrease the clearances. Another reason is that the creep of alkaline on copper surface is decreased by the effect of epoxy resin. It has been proven that the mixture of epoxy resin and asphalt has good characteristics for sealing alkaline electrolyte by the mass production batteries. Absorbing the diphenylcarbazide to anode can copper surface brought out good seal characteristics for the silver oxide batteries. In conclusion, the mechanism of leakage of the silver oxide battery is that the electrolyte invades into clearances between the seal consisted by gasket and anode can and it generated hydrogen gas on copper surface, which made gas hall and leak path. It has also been proven that decreasing hydrogen gas generation is one of the most important ways to get better sealing.

Influence of Increased Temperature from Cement Hydration on Aluminum Corrosion Prevention When LiNO3 Is Added to the Cement

The influence of increased temperature from cement hydration was checked on aluminum corrosion prevention when LiNO3 was added to the cement used for aluminum waste cementation.At first, the temperature at the center of a 0.2-m3 cement or mortar form was measured. Then, because the reaction mechanism of LiNO3 involves formation of insoluble LiH 2AlO2 5H2O (Li-Al) preservation film on an aluminum surface, the Li-Al film solubility was measured in a 0.1 M KOH aqueous solution at temperatures from 283 to 353 K. In a second experiment, an aluminum specimen was soaked in a 0.1 M KOH solution with 3 wt% of dissolved LiNO3, and the volume of generated hydrogen gas was measured. Finally, aluminum plates were solidified with mortar in a full-scale test. The mortar mixture contained ordinary portland cement (OPC), blast furnace slag (BFS), and sand with a 1.5 wt% LiNO3 addition, and the volume of generated hydrogen gas was measured.When only OPC was used, the temperature increased to ~363 K. With the BFS and sand addition, this temperature increase was reduced by ~40 to 323 K. The Li-Al film solubility became larger as the temperature of the solution increased. The volume of hydrogen gas generation became large as the temperature increased, especially over 323 K. When the mortar consisted of OPC, BFS, sand, and LiNO3, the volume of hydrogen gas generation from aluminum was reduced, becoming <10% of that without the LiNO3 addition. Thus, it appears that the temperature did not have much influence on the ability of LiNO3 to prevent aluminum corrosion, although the ability was gradually lessened as the temperature increased.

Plating fog generation in the forming of printed circuits by the additive method

Plating fog is often observed when metallizing a latent pattern by electroless copper plating. Metallic elements in the nuclei of plating fog particles are analysed using electron probe microanalysis (EPMA). Silver and iron are invariably found in the particles. The iron is driven into the board during the liquid honing process and reduces silver ions in the photosensitive material to silver metal which causes plating fog. Plating fog also arises from reduced copper particles or generated hydrogen gas bubbles when they are trapped on the unpatterned region. Mechanical stirring accompanied by substrate oscillation is an effective method of avoiding plating fog.

LiNO3Addition to Prevent Hydrogen Gas Generation from Cement-Solidified Aluminum Wastes

LiNO3 addition to the cement solidified miscellaneous wastes has been proposed for preventing hydrogen ges generation caused by the corrosion of aluminum materials contained in the wastes. To determine an additive among alkaline metal ions, galvanic current was measured in 0.1 M alkaline metal hydroxide solution between aluminum and platinum electrodes. The volume of hydrogen gas generated from an aluminum specimen was measured in a KOH solution with LiNO3, LiCl, LiBr, Li2CO3 or Li2SO4 to decide the best additive. Applicability of the chosen additive to cement was confirmed by hydrogen gas generation measurement from an aluminum specimen in cement paste. The prevention mechanism was analyzed by X-ray diffraction, SEM and SIMS. The current measured in LiOH solution decreased with time, then reached 0 μA/mm2, while the current was detected in other alkaline metal hydroxide solutions. The least volume of hydrogen gas generation was measured in a KOH solution with LiNO3. The volume of generated hydrogen gas i...