Dry Oxygen Research Articles

Mechanism of Boron Carbide Oxidation in a Dry Environment

ABSTRACT We analyze in detail the published experimental data on the high-temperature oxidation of compact boron carbide in dry oxygen in the range of 600–1200°C. The results of the analysis show that the oxidation of boron carbide occurs with the accumulation of excess (compared to stoichiometry) boron. Using experimental data, the time dependences of the thickness of the boron oxide melt layer formed on the sample surface during its oxidation and the mass of boron oxide evaporated from the sample surface are determined. For different temperatures, the evaporation rates of boron oxide are determined. Based on the analysis, a model of the high-temperature oxidation of compact boron carbide in dry environment was developed. Using the developed model, calculations of the process of boron carbide oxidation at different temperatures were carried out. Based on the results of calculations, the time dependences of the mass of the sample, the mass of the resulting carbon dioxide, and the thickness of the boron oxide melt layer were determined. The calculation results are compared with the experimental data and with the theoretical temperature dependence of the boron oxide melt evaporation rate, calculated using the Hertz – Knudsen equation. Based on the simulation results, it is concluded that the rates of chemical reactions are finite, and the process of B4C oxidation cannot be reduced only to oxygen diffusion through the boron oxide layer.

Synthesis of nano tungsten carbide via loose yellow tungsten oxide rod processing

Nano tungsten carbide (WC) was synthesized using loose yellow tungsten oxide (WO3) rods, which were derived from violet tungsten oxide (WO2.72) through calcination in dry oxygen. The WO3 rods were then subjected to ball milling with carbon black, followed by carbothermal reduction and carbonization. Unlike conventional methods such as hydrogen reduction or carbothermal reduction, this technique avoids the formation of hydrated tungsten oxides and addresses challenges related to precise carbon control and matching. This streamlined procedure produces nanoscale tungsten carbide particles approximately 150 nm in size, showing great potential for future industrial applications.

The Lubricity of Gases

A sealed reciprocating tribometer has been used to study the influence of different gaseous environments on the friction and wear properties of AISI52100 bearing steel at atmospheric pressure and 25 °C. Helium, argon, hydrogen, carbon dioxide and nitrogen all give high friction and wear, suggestive of very little, if any tribofilm formation under the conditions studied. Dry air and oxygen also give high friction, slightly lower than the inert gases, but produce extremely high wear, much higher than the inert gases. This is characteristic of the phenomenon of “oxidational wear”. The two gases ammonia and carbon monoxide give relatively low friction and wear, and XPS analysis indicates that this is due to the formation of adsorbed ammonia/nitride and carbonate films respectively. For the hydrocarbon gases studied, two factors appear to control friction and wear, degree of unsaturation and molecular weight. For the saturated hydrocarbons, methane and ethane give high friction and wear but propane and butane give low friction after a period of rubbing that decreases with molecular weight. The unsaturated hydrocarbons all give an immediate reduction in friction with correspondingly low wear. Raman analysis shows that all the hydrocarbons that reduce friction and wear form a carbonaceous tribofilm on the rubbed surfaces.Graphical

Oxidation behavior of SiC‐AlN ceramics exposed to dry oxygen and water oxygen environments at 1100–1300°C

AbstractThe corrosion of SiCf/SiC composites in gas environment threatens their long‐term service in aeroengines as hot‐end structure components. Addition of corrosion‐resistant phases into SiC matrix is a potential strategy to improve the service performance of SiCf/SiC materials. Here, AlN added SiC ceramics were prepared by reactive melt infiltration, and the effect of AlN phase on the oxidation resistance of the ceramics was emphasized. The oxidation tests were performed in dry oxygen and water oxygen atmospheres at 1100°C–1300°C, respectively. The oxidation mechanism was discussed based on the microstructure evolution of the oxide layer. The results show that the oxide layer is composed of aluminum silicate glass and Al2O3 flakes dispersedly distributed in the glass phase. As the temperature rises, the oxide layer gradually grows and thickens. Finally, a smooth and dense protective layer could be formed on the surface of ceramics to resist oxidation. This study can provide a profound insight to construct SiCf/SiC composites with excellent oxidation resistance.

Characterization of δ-PuGa (1 at%. Ga) Oxidation Under Dry Oxygen Atmosphere Exposure

The oxidation of δ-stabilized plutonium alloy was studied under dry oxygen exposures for temperatures varying from 100 up to 300 °C and oxygen partial pressures varying from 10–4 up to 500 mbar. The coupling of X-ray diffraction, Raman spectroscopy and FIB-SEM has allowed to show that the oxide scale is composed of an outer layer of PuO2 and an inner mixed layer of α + β-Pu2O3 platelets propagating into a metallic zone corresponding to the stable phase of unalloyed Pu. Furthermore, the analysis of Pu oxidation kinetics has displayed first a parabolic growth governed by the diffusion of interstitial oxygen. This step consists of the thickening of the Pu2O3 layer with a decrease in α-Pu2O3 ratio in favor of β-Pu2O3. Then, a second step occurs consisting of a linear growth of the PuO2-layer with the formation of thick nodules which tend to cover the whole oxide surface. Based on the results of this work, a general oxidation mechanism for δ-Pu alloy is provided.

Chromium(II)-isophthalate 2D MOF with Redox-Tailorable Gas Adsorption Selectivity.

Redox-active metal-organic frameworks (MOFs) are very promising materials due to their potential capabilities for postsynthetic modification aimed at tailoring their application properties. However, the research field related to redox-active MOFs is still relatively underdeveloped, which limits their practical application. We investigated the self-assembly process of Cr(II) ions and isophthalate (m-bdc) linkers, which have been previously demonstrated to yield 0D metal-organic polyhedra. However, using the diffusion-controlled synthetic approach, we demonstrate the selective preparation of a 2D-layered Cr(II)-based MOF material [Cr(m-bdc)]·H2O (1·H2O). Remarkably, the controlled oxidation of the developed 2D MOF using nitric oxide or dry oxygen resulted in modified porous materials with excellent H2/N2 adsorption selectivities.

Effects of Hydrogen Plasma Treatment on the Electrical Behavior of Solution-Processed ZnO Thin Films.

In this study, the effect of atmospheric hydrogen plasma treatment on the in-plane conductivity of solution-processed zinc oxide (ZnO) in various environments is reported. The hydrogen-plasma-treated and untreated ZnO films exhibited ohmic behavior with room-temperature in-plane conductivity in a vacuum. When the untreated ZnO film was exposed to a dry oxygen environment, the conductivity rapidly decreased, and an oscillating current was observed. In certain cases, the thin film reversibly 'switched' between the high- and low-conductivity states. In contrast, the conductivity of the hydrogen-plasma-treated ZnO film remained nearly constant under different ambient conditions. We infer that hydrogen acts as a shallow donor, increasing the carrier concentration and generating oxygen vacancies by eliminating the surface contamination layer. Hence, atmospheric hydrogen plasma treatment could play a crucial role in stabilizing the conductivity of ZnO films.

Light-induced photoluminescence enhancement in chiral CdSe quantum dot films.

Chiral quantum dots (QDs) are promising materials applied in many areas, such as chiral molecular recognition and spin selective filter for charge transport, and can be prepared by facile ligand exchange approaches. However, ligand exchange leads to an increase in surface defects and reduces the efficiencies of radiative recombination and charge transport, which restricts further applications. Here, we investigate the light-induced photoluminescence (PL) enhancement in chiral L- and D-cysteine CdSe QD thin films, providing a strategy to increase the PL. The PL intensity of chiral CdSe QD films can be significantly enhanced over 100 times by continuous UV laser irradiation, indicating a strong passivation of surface defects upon laser irradiation. From the comparative measurements of the PL intensity evolutions in vacuum, dry oxygen, air, and humid nitrogen atmospheres, we conclude that the mechanism of PL enhancement is photo-induced surface passivation with the assistance of water molecules.

Oxidation of silicon particles suspended in a mullite matrix with dual-mode vacancy diffusion of oxygen

Mullite bond coats filled with silicon particles have recently been proposed for the next generation of environmental barrier coatings (EBC). The sacrificial oxidation of the silicon particles eliminates some of the environmental durability issues associated with traditional EBC designs. To investigate this novel design approach, a mathematical formulation and resulting numerical method have been developed for simulating the oxidation of silicon particles embedded in a mullite matrix. The focus is on the oxidation of the silicon in a dry oxygen environment where the oxidant is presumably oxygen. Oxygen transport from the exterior environment through the mullite is assumed to occur via two lattice defect diffusion mechanisms. As a result, the rate of oxygen transport is dictated by the self-diffusivity of the lattice defects. The numerical method is implemented using the COMSOL Multiphysics® Program. The method is applied to simulate the oxidation of silicon particles in a mullite pellet in recent oxidation experiments. Numerical results compare favorably with the oxidation behavior observed in the oxidation experiments. The numerical method is also used to investigate the effects of various features of the mullite/silicon particle system on the oxidation behavior.

Control of Liquid Water Transport in Cathode of PEFC Using Wettability-Patterned Electrodes

During the operation of polymer electrolyte fuel cells (PEFCs), the product water that accumulates in the cathode electrode blocks the oxygen transport to the reaction sites and causes severe performance degradation. This phenomenon, known as “flooding,” is one of the critical issues to be solved for achieving high efficiency and high power density. To alleviate water flooding, it’s necessary to design an electrode/channel structure that could actively remove liquid water from the porous electrode. Zhang et al. [1] reported that the wettability patterning of a gas diffusion layer (GDL) enables it to provide the liquid water pathway in the cathode electrode. Furthermore, Nishida et al. [2] demonstrated that the hydrophilization of cathode channel walls promotes water removal from the GDL to the flow channel. This study fabricated a wettability-patterned GDL impregnated with a hydrophilic silica-based solvent and newly proposed an electrode/channel structure combining the patterned electrode and hydrophilized flow channel. The effect of its structure on the liquid water distribution within the cathode GDL of an operating PEFC was also investigated using X-ray imaging.The authors fabricated the experimental fuel cell with an effective electrode area of 1.8 x 1.6 cm2. The membrane electrode assembly (MEA) was sandwiched between two carbon separators with a single-serpentine flow field (number of channels: 7, channel width: 1.0 mm, depth: 1.0 mm, total length: 88.5 mm). Fig. 1 shows the regions measured by X-ray imaging in the cross-sectional view of the cathode. Since the cathode GDL is irradiated with an X-ray beam in the in-plane direction, the through-plane distributions of water can be observed in the GDL. The measurement regions were set under the 4th channel and under the land between the 3rd and 4th channel. The GDL in the cathode was impregnated with the silica-based solvent in the range of 0.3 mm width x 10 mm length x 0.1 mm depth. The hydrophilized region was positioned along the right sidewall of the 4th channel. The channel walls of the cathode were also coated with the same hydrophilic solvent. Fig. 2 represents the distribution of water saturation in the (a) uncustomized and (b) wettability-patterned GDL. The current density was increased stepwise from 0.14 to 1.02 A/cm2 for 8 min at room temperature and non-humidified condition. All images were captured at t=6 min after starting the operation. Dry hydrogen (stoichiometry: 1.5@2.0A/cm2) and oxygen (stoichiometry: 3.0@2.0A/cm2) were supplied to the anode and cathode, respectively, in a counter-flow arrangement. As shown in Fig. 2(b), it was noted that the water saturation around the hydrophilized region was effectively reduced due to the in-plane water suction. The patterned GDL partially impregnated with the highly hydrophilic solvent enables to induce the product water from the hydrophobic to hydrophilic region, resulting in the reduction of flooding. To further accelerate the through-plane water transport from the hydrophilized region in the GDL to the channel sidewall, it’s essential to introduce a difference in their wettability and optimize their combinations.

Study on the optical properties of new multi-waveband transmission fluoroaluminate-tellurite glasses

A new mid-infrared fluoroaluminate-tellurite glass with low hydroxyl absorption coefficient and high visible-infrared transmittance was fabricated by the high temperature melt casting method. The melting equipment was innovatively designed by placing lift furnaces in the glove box filled with dry oxygen to assure waterless preparation. The glass prepared in the glove box had low hydroxyl absorption coefficients (0.09 cm−1), validating the effectiveness of the water removal equipment. The glass was obtained with excellent thermal stability (Tg > 450 °C) and good resistance to crystallization based on thermodynamic analysis (ΔT > 100 °C). The transmittance of glass maintained 80–91.30 % from 371 to 5572 nm, achieving high transmittance in multi-waveband. The glass had excellent optical and composition homogeneity indicated by refractive index and EDAX. The results showed that this glass had high thermal stability, visible-infrared transmittance and optical homogeneity, making it a good candidate for multi-waveband optical window materials.

Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays.

A fundamental understanding of the electrochemical reactions and surface chemistry at the solid-gas interface in situ and operando is critical for electrode materials applied in electrochemical and catalytic applications. Here, the surface reactions and surface composition of a model of mixed ionic and electronic conducting (MIEC) perovskite oxide, (La0.8Sr0.2)0.95Cr0.5Fe0.5O3-δ (LSCrF8255), were investigated in situ using synchrotron-based near-ambient pressure (AP) X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS). The measurements were conducted with a surface temperature of 500 °C under 1 mbar of dry oxygen and water vapor, to reflect the implementation of the materials for oxygen reduction/evolution and H2O electrolysis in the applications such as solid oxide fuel cell (SOFC) and electrolyzers. Our direct experimental results demonstrate that, rather than the transition metal (TM) cations, the surface lattice oxygen is the significant redox active species under both dry oxygen and water vapor environments. It was proven that the electron holes formed in dry oxygen have a strong oxygen character. Meanwhile, a relatively higher concentration of surface oxygen vacancies was observed on the sample measured in water vapor. We further showed that in water vapor, the adsorption and dissociation of H2O onto the perovskite surface were through forming hydroxyl groups. In addition, the concentration of Sr surface species was found to increase over time in dry oxygen due to Sr surface segregation, with the presence of oxygen holes on the surface serving as an additional driving force. Comparatively, less Sr contents were observed on the sample in water vapor, which could be due to the volatility of Sr(OH)2. A secondary phase was also observed, which exhibited an enrichment in B-site cations, particularly in Fe and relatively in Cr, and a deficiency in A-site cation, notably in La and relatively in Sr. The findings and methodology of this study allow for the quantification of surface defect chemistry and surface composition evolution, providing crucial understanding and design guidelines in the electrocatalytic activity and durability of electrodes for efficient conversions of energy and fuels.

The Cultivation of Scallop (Patinopecten yessoensis) in Hokkaido, Japan

Scallop culture is a widely practiced aquaculture activity in Japanese waters that involves collecting wild scallop spat and then growing the spat to a marketable size. This study aims to determine how the cultivation system, technology, and transportation are applied in scallop aquaculture in Japan. This research was conducted from December 2022 to June 2023 at a family scallop farming business in Ishikari, Hokkaido, Japan, hereafter referred to as Company X. This research utilizes a descriptive method with literature exploration and direct observation methods with a case study at Company X.Based on the literature study and activities at Company X, the cultivation media used and transportation are important parts of the scallop culture activities. The cultivation media used at Company X include onion mesh bags, Pearl nets, and lantern nets. The current transportation technology of scallops is carried out in two areas, namely sea, and land, using the open dry system transportation method, exposure method, and oxygen method. Marine transportation uses Hydraulic Cranes for Shipboard Use (Marine Cranes) technology applied to two specialized vessels of 9.7 and 12 GT with truck-mounted crane classification. Land transportation for the delivery of young scallops uses plastic container baskets covered with wet rice sacks to prevent dryness and the scallops inside the baskets from biting each other. After that, the scallops are transported by freezer truck, while land transportation for shipping adult scallops uses a freezer truck filled with oxygenated seawater. The size of the wind blowing at sea, the time of pickup - delivery, and the number of scallops needed are important factors in transportation activities.

Current Leakage and Faradaic Efficiency Simulation of Proton-Conducting Solid Oxide Electrolysis Cells

In this study, we simulated BZY electrolyte-supported proton-conducting solid oxide cell by coupling surface defect chemistry reaction with charged species transport. We validated the model parameters by concentration as a function of temperature, conductivity under dry and wet oxygen as a function of oxygen partial pressure and temperature. The results indicate that the high electron-hole mobility (diffusivity) is mainly responsible for the high leaking current under high temperatures. The Faradaic efficiency stays low or even negative under low operating voltage or high temperature and plateaus as the cell voltage increases. The model developed in this study is a useful tool to understand the leaking current in BZY electrolyte and provide design strategies to avoid/mitigate such significant inefficiency for water electrolysis operation.

The effect of the synthesis conditions on the crystal structure of palladium(II) oxide nanofilms

Nanocrystalline films of palladium(II) oxide obtained by oxidation of the initial metallic Pd layers with a thickness of 35 nm on Si (100) substrates in atmospheric air were studied using XRD analysis, TEM, and RHEED. PdO/SiO2/Si (100) heterostructures were synthesised in two stages. First, we obtained finely dispersed layers of metallic Pd on SiO2/Si (100) substrates with an ~ 300 nm SiO2 buffer layer using thermal sublimation in a high vacuum. The Pd layers were then oxidised in the temperature range Tox = 620 – 1100 K in atmospheric air (with the partial pressure of oxygen of about 21 kPa). The study determined that the deformation of the tetragonal crystal structure of homogeneous nanocrystalline PdO films is explained by an increase in the values of lattice parameters with the oxidation temperature. The deformation reaches its maximum values at Tox ~ 970 K. Comparison of the obtained results with the earlier data regarding PdO/SiO2/Si (100) heterostructures synthesised in a dry oxygen atmosphere (with the partial pressure of oxygen of about 101.3 kPa) demonstrated that PdO films synthesized in an oxygen atmosphere are characterized by a higher degree of deformation of the crystal structure. The effect of the oxidation temperature and O2 partial pressure on the increase in the tetragonal lattice parameters of the PdO films can be explained by the formation of interstitial oxygen atoms in the octahedral void in the centre of the palladium(II) oxide unit cell.

Oxidation and corrosion behavior of 2D laminated SiC/SiC with Si/mullite/BSAS EBC in dry oxygen/water vapor at 1200 °C

Si/mullite/BSAS EBC were plasma sprayed on SiC/SiC and their oxidation and corrosion behavior were investigated in dry oxygen and water vapor at 1200 °C. A modified thermal-oxidation kinetic model was used to estimate the permeability of water vapor and dry oxygen in the mullite/BSAS and SiO2 layer, respectively. The contribution of EBC to the oxidation/corrosion process and that of SiC/SiC substrates were extracted. The method of permeability calculation and contribution extraction in this work provides a direct evaluation of the protective effect of EBCs and can be used as a criterion to compare different EBC systems.

Synthesis of ZnO nanoparticles via spray atomization assisted inductively coupled plasma technique

Spray atomization-assisted inductively coupled plasma system, for the first time, was utilized to synthesize ZnO nanoparticles at atmospheric pressure from a liquid precursor with varying process parameters, such as precursor concentrations and flow rates, carrier gas flow rates, and with or without the utilization of quenching gas (dry air or oxygen). The ZnO nanoparticles were characterized by FTIR, XRD, TEM, and SAED methods to evaluate the effect of process parameters on the morphology, particle size and size distribution of the final particles. The particles were in equiaxed morphology with mean particle sizes varying between 17.5 ± 9.5 nm and 25.7 ± 11.2 nm.

Influence of External Conditions on the Black-to-Yellow Phase Transition of CsPbI3 Based on First-Principles Calculations: Pressure and Moisture

All-inorganic CsPbI3 perovskite has emerged as a promising candidate for next-generation solar cells. However, owing to the poor structural stability of black phase CsPbI3 perovskite at room temperature, it spontaneously transforms to the yellow, photoinactive, nonperovskite phase at room temperature, limiting further development of CsPbI3 perovskite solar cells. To better understand the mechanism driving such undesirable phase transformation, we examine the thermodynamics and kinetics associated with γ-to-δ phase transformation using density functional theory calculation. A solid-state nudged elastic band method was employed to find minimum energy pathways assuming a concerted solid-state phase transformation between these two phases. The gas molecules representing atmospheric (H2O, O2, and N2) and inert (Ar) ambient environments, as well as applied external pressure, were considered to examine the influence of external conditions on the black-to-yellow phase transition. Our calculation reveals that, with increasing pressure, the thermodynamic driving force for converting the γ-phase to the δ-phase increases, whereas a larger activation energy must be overcome for the phase transition to occur. We also investigate the moisture-induced phase transformation with an H2O molecule and its dissociated species (H+/OH–) and demonstrate that the reaction energy barriers can be significantly lowered in the presence of H2O or OH–. On the other hand, other nonpolar species (O2, N2, and Ar) have a negligible effect on the phase transformation kinetics, while they might reduce the thermodynamic driving force for the phase transformation and suppress the undesirable phase transformation. Our theoretical prediction could support recent observations that the γ-to-δ phase transformation occurs rapidly and catalytically in the presence of moisture, whereas in dry argon and dry oxygen atmospheres, the γ-CsPbI3 remains stable.

Syngas production from municipal sewage sludge by gasification Process: Effects of fixed bed reactor types and gasification agents on syngas quality

In this experimental study, the results obtained from sewage sludge gasification carried out in two different fixed bed gasifiers, up draft and down draft, are presented. In addition, the effects of using three different heating temperatures (700, 800, 900 °C), two different gasification agents (dry air and pure oxygen), and their different flow rates (0.05, 0.1, 0.2, 0.4 L/min for dry air, 0.01 L/min for pure oxygen) on gasification efficiency are investigated. 75 g of sludge sample was used in each experimental study. The syngas composition produced from sludge gasification studies was measured by using online syngas analyzers. The maximum H2 content in syngas from updraft and downdraft gasifiers was achieved as 42 vol% and 46 vol% by using dry air as gasifying agent. H2 content for updraft and downdraft gasifiers was also obtained as 40 vol% and 45 vol%, respectively in the case of pure oxygen used as a gasifying agent. This paper presents a critical discussion identifying key points and contributing to a deeper understanding of its remarkable potential for sludge gasification by using different fixed bed gasifier configurations.

(Digital Presentation) Effect of Compression Pressure on Water Removal and Power Generation Performance of PEFC with Modified Electrode/Channel Structure

Water flooding in cathode electrodes of polymer electrolyte fuel cells (PEFCs) is a critical issue that must be solved for achieving high efficiency and high power density operations. To alleviate this problem, it is necessary to design the optimum electrode/channel structure for actively removing liquid water from the porous media to the flow channel. In the previous studies, Okuhata et al. [1] revealed that the introduction of penetration holes to gas diffusion electrodes (GDEs) effectively promotes the water discharge and improves the limiting current density. Nishida et al. [2] investigated the effect of channel hydrophilization on the water behavior in the cathode of an operating cell using the cross-sectional visualization technique. It was found that the hydrophilization of cathode channels encourages the water suction from the gas diffusion layer (GDL) to the channel and enhances the oxygen diffusibility to the catalyst layer (CL). Our research group has proposed a novel hybrid electrode/channel structure combining the electrode perforation and channel hydrophilization and has investigated its effect on the improvements of water drainage and cell performance. In this study, we directly visualized the liquid water distribution in the cathode GDL of a customized PEFC with the hybrid electrode/channel structure using X-ray imaging and evaluated the transient response of cell voltage under the constant-current operations. Furthermore, the influence of compression pressure on the water behavior in the perforated GDL and the performance characteristics of the customized cell was also examined.For the X-ray investigation, we fabricated a specialized miniature fuel cell with the effective electrode area of 2.88 cm2. The membrane electrode assembly (MEA) was sandwiched between two carbon separators with a single-serpentine flow field (number of channels: 7, channel width: 1.0 mm, depth: 1.0 mm, total length: 88.5 mm). Fig. 1 shows a schematic cross-sectional view on the cathode side of the experimental cell. Since the cathode GDL is irradiated with X-ray beam in the in-plane direction, the through-plane distributions of water can be observed in the GDL under the 4th channel and under the land between the 3rd and 4th channel. To promote the water discharge from the fine porous media, a penetration groove (width: 300 μm, length: 11 mm) was installed into the GDL, MPL and CL and positioned along the right sidewall of the 4th channel. The channel walls on the cathode side were coated with the silica-based hydrophilic solvent. The contact angle of water on the hydrophilized channel is 9.8o. In the hybrid electrode/channel structure, liquid water accumulated in the CL and MPL is firstly discharged into the large groove in the in-plane direction. Subsequently, water droplets gathered in the groove are grown up and attached to the hydrophilized channel walls. The droplets are spread out on the hydrophilic sidewalls and the liquid films are moved upward. Fig. 2 presents the distributions of water saturation in the perforated GDL of the customized cell assembled under two different compression pressures of 0.5 and 1.0 MPa. The current density was increased stepwise from 0.14 to 1.02 A/cm2 for 8 min under the room temperature and non-humidification condition. All images were captured at t=8 min after starting the operation. Dry hydrogen (stoichiometry: 1.5@2.0A/cm2) and oxygen (stoichiometry: 3.0@2.0A/cm2) were supplied to the anode and cathode in the counter-flow arrangement. It was found that the introduction of the hybrid structure effectively decreases the water saturation around the groove due to the in-plane water discharge. The reduction of saturation under the land is much less than under the channel because the strong mechanical compression crushes the pore structure under the land regions and suppresses the water transport. In addition, the low-saturation region of 28% or less around the groove is enlarged with a decrease in compression pressure. The low compression pressure maintains the relatively large porosities in diffusion media and facilitates the water removal.