Phosphoric Acid Research Articles

Atroposelective synthesis of axially chiral imidazo[1,2-a]pyridines via asymmetric multicomponent reaction.

Imidazo[1,2-a]pyridines are privileged heterocycles with diverse applications in medicinal chemistry; however, the catalytic asymmetric synthesis of these heterocyclic structures remains underexplored. Herein, we present an efficient and modular approach for the atroposelective synthesis of axially chiral imidazo[1,2-a]pyridines via an asymmetric multicomponent reaction. By utilizing a chiral phosphoric acid catalyst, the Groebke-Blackburn-Bienaymé reaction involving various 6-aryl-2-aminopyridines, aldehydes, and isocyanides gave access to a wide range of imidazo[1,2-a]pyridine atropoisomers with high to excellent yields and enantioselectivities. Extensive control experiments underscored the pivotal role of the remote hydrogen bonding donor on the substrates in achieving high stereoselectivity for these reactions. The versatile derivatizations of these atropisomeric products, especially their role as an analog of NOBINs and their facile conversion into unique 6,6-spirocyclic products, further emphasize the merits of this methodology.

Bulk stereoselective cationic polymerization of vinyl ethers by the coordination of ZrCl4 with tunable spirocyclic phosphoric acids.

Control over stereochemistry in poly(vinyl ether)s leads to a notable change in their physical properties, yet remains a grand challenge. Here, we demonstrate the bulk stereoselective cationic polymerization of vinyl ethers using ZrCl4 coordinated with a spirocyclic phosphoric acid (SPA). The widely variable substituents in SPAs exert a profound impact on the stereochemical and activity outcome of the polymerization: the % m of poly(vinyl ether)s linearly increases with the Hammett substituent constant (σ) of SPAs; the catalytic activity increases with the σ; the large steric hindrance groups lead to decreased polymerization activity. Mechanism studies suggest that the coordination of ZrCl4 with three equivalents of SPAs generates the chiral complex. The complex can abstract chlorine from the initiator/chain end to form the chiral ion pair allowing the selective facial addition of incoming monomers. The catalyst system features characteristics of no solvent, low loads, high tacticity control, high monomer scope, and recyclability.

The Effect of p-Toluenesulfonic Acid and Phosphoric Acid (V) Content on the Heat Resistance and Thermal Properties of Phenol Resin and Phenol-Carbon Composite

This work presents the results of research on the influence of the amount of p-toluenesulfonic acid and phosphoric acid (V) added to the phenol-formaldehyde resin (pH 7.3–7.8) on its thermal properties and on the phenol-formaldehyde-carbon composite produced on its basis. This material undergoes pyrolysis under high temperature. The addition of a catalyst to the phenol-formaldehyde resin affects its curing rate and degree of cross-linking, but how it affects the thermal properties of the resin depending on the temperature is the subject of this work. This article presents the results of thermal tests for phenol-formaldehyde resin and phenol-formaldehyde-carbon composite. It was examined how the content of the catalyst used during the production process affects the individual thermal parameters of the mentioned materials. The results include experimental tests of thermal diffusivity with uncertainty (±3%), specific heat capacity (±2.5%), thermal expansion with resolution 2 nm analyzed in the temperature range −40–115 °C and thermogravimetric TG/DTA analysis with resolution 0.03 µg in the temperature range from room temperature (RT = 23 °C) to 550 °C. Individual thermal tests showed changes in the thermal properties caused by changes in the catalyst content of the tested materials and the influence of the addition of carbon fibers on the properties of the composite compared to the pure phenol-formaldehyde resin. It was found that there is a certain maximum level of catalyst weight fraction at which the greatest decrease in thermal diffusivity occurs. In the case of phenolic-formaldehyde-carbon composite at −40 °C, an increase in catalyst weight fraction from 2 to 4 wt% caused a decrease in thermal diffusivity by 18.2%, and for phenol-formaldehyde resin, it was 2.8% with an increase in catalyst fraction from 4 to 10 wt%.

Anodization of Aluminum in a Sodium Hydroxide Solution: Effect of pH on Chemical Dissolution

Abstract The chemical dissolution of anodic alumina film was investigated using the re-anodization technique. The formation of thick oxide films in an alkaline electrolyte is thought to be difficult to achieve due to the high pH value and high solubility of anodic alumina. The dissolution rate of anodic film was found to be strongly affected by the pH of the solution used for chemical dissolution; the film dissolved significantly faster in a sodium hydroxide solution having a high pH of 13.11 than in acidic solutions commonly used for anodization, such as sulfuric acid (pH 0.98) and phosphoric acid (pH 1.54). Nevertheless, the addition of glycerol to the sodium hydroxide solution effectively suppressed the chemical dissolution of the anodic film. The change in solubility of the anodic alumina film in solution was greatly affected by the change in the dissociation of the solute in solution. The results demonstrated that oxide films more than 10 μm thick were produced in an alkaline electrolyte by adding glycerol to the solution. The suppression of the chemical dissolution of alumina by the addition of alcohol has thus been shown to occur not only in acid solutions but also in alkaline solutions.

Production of oil palm frond activated carbon by microwave-assisted phosphoric acid activation for removal of Remazol Brilliant Orange 3R: Response surface methodology optimization

Production of oil palm frond activated carbon by microwave-assisted phosphoric acid activation for removal of Remazol Brilliant Orange 3R: Response surface methodology optimization

Semi-direct restorative technique for aesthetic and functional restoration in posterior teeth: case report

The semi-direct restorative technique using composite resin has gained increased popularity in clinical practice due to several advantages: reduced cost for patients, the feasibility of composite resin restorations in teeth with significant structural loss, time[1]saving, improved margin adaptation, polishing, polymerization, and aesthetics of the restoration performed outside the mouth. Objective: The aim of this study was to present a clinical case involving the restoration of posterior teeth with substantial coronal destruction using the semi-direct technique. Case report: The tooth was prepared (defective restoration removal) following onlay preparation guidelines. The preparation was then molded using alginate, and the model was obtained in elastomeric material (addition-polymerized silicone). A composite resin restoration was crafted on the model, photoactivated, and polished outside the mouth. Following the resin restoration on the silicone model, it was cemented onto the prepared tooth. Absolute isolation was employed, the temporary restoration was removed, and the preparation was cleaned. For cementation, sandblasting with aluminum oxide in the internal portion, etching with phosphoric acid, and the application of an adhesive system were performed. Subsequently, a dual polymerization resin cement was manipulated, applied to the resin piece, and placed on the prepared tooth. Excess cement was removed, and the piece was photoactivated for 40 seconds on each surface. Finally, the piece’s adaptation was verified, occlusal contacts were checked, and finishing and polishing were carried out. Conclusion: It can be concluded that the semi-direct composite resin restoration enabled achieving improved anatomy, marginal adaptation, polishing, and resistance, consequently enhancing clinical longevity with a better cost-benefit ratio for the patient.

The ability of austenitic stainless steel (Alloy-28) to withstand corrosion when exposed to a combination of industrial phosphoric acid and an oxidizing agent

The ability of austenitic stainless steel (Alloy-28) to withstand corrosion when exposed to a combination of industrial phosphoric acid and an oxidizing agent

Prescription versus over-the-counter venotonics: HPLC-DAD and static digestive model simulation comparison.

Venotonics are a class of therapeutically active molecules that have vaso-protective effects. They are used to alleviate venous diseases and disorders, particularly venous insufficiency. We compared the composition of prescription versus over-the-counter (OTC) venotonics using high-performance liquid chromatography with UV detection (HPLC-DAD) and simulating their digestion using a static digestive model. From each drug, five tablets were weighed. A homogenate was prepared, and 25 mg of crushed homogenized tablets were weighed into 25 ml volumetric flasks. Dissolved in MeOH and added two drops of saturated NaOH solution. The samples were filtered into vials (Teflon, 0.45 μm) and used for analysis. An Ultimate 3000 HPLC system (Thermo Fisher Scientific, Waltham, MA, USA) consisting of a quaternization pump, autosampler, column thermostat and DAD (UV/VIS detector) was used. The composition of the mobile phase proceeded in a linear gradient from 30% methanol and 70% phosphoric acid (0.15%) in water at time t=0 min. to 80% methanol and 20% phosphoric acid (0.15%) at time t=15 min., at a constant mobile phase flow rate of 1.2 mL/min. Detection was performed using a DAD detector in the 190-450 nm wavelength range. The content of monitored flavonoids was calculated from peaks at a wavelength of 277 nm, in which both flavonoids have their absorption maxima. The static digestive model was used to simulate the digestive phase from the oral cavity to the corresponding intestinal phase. The content of diosmin and hesperidin (mg per table) for a prescription drug: Detralex: 480 mg, 26 mg. The content of diosmin and hesperidin (mg per tablet) for OTC drugs: Venostop: 502 mg, 48 mg, Diosminol: 520 mg, 50 mg, Devenal: 496 mg, 49 mg, Diohes: 493 mg, 46 mg. Digestion did not affect the solubility of all tested drugs. The active substances could not be determined in the non-alkalized sample. After alkalization, part of the insoluble matter was visibly dissolved and converted to a yellow flavonoid complex. Neither diosmin nor hesperidin could be identified afterwards. Our experimental results show that the contents of both listed active substances, diosmin and hesperidin, met the declared amounts in all tested medicaments. Digestion simulation showed identical behaviour in prescription and OTC venotonics. The active substances could not be determined in the non-alkalized sample. Digestion did not affect the solubility of the tested drugs.

Design of Experiment and green analytical chemistry principles for developing a robust and sustainable Stability-Indicating HPLC method for Bempedoic acid impurity profiling

Bempedoic acid (BEM), a drug used to lower cholesterol levels in patients with atherosclerosis. Controlling its process-related impurities is crucial due to their potential toxicity. This study details the development of a RP-HPLC method for the analysis of four process-related substances in BEM. To ensure robust chromatographic performance meeting six sigma quality standards, the method was optimized using a combined approach of response surface methodology (specifically, an I-optimal design) and tolerance analysis, integrating predefined specifications for critical method attributes such as resolution, tailing factor, and number of theoretical plates into the developmental process. Chromatographic separation was achieved using a C18 column. The mobile phase consisted of 0.1 % phosphoric acid in water and acetonitrile, utilizing a stepped gradient elution profile. The flow rate was maintained at 0.9 mL/min, with UV detection performed at 210 nm. The column temperature was set to 20 °C. The method demonstrated linearity for BEM process related impurities in the range of LOQ to 30 μg mL−1. The method ability to differentiate the drug substance from its degradation products was confirmed through forced degradation study. The environmental sustainability of the developed method was assessed using multiple Green Analytical Chemistry (GAC) tools. The National Environmental Methods Index (NEMI) showed two green-shaded quadrants, and the Green Certificate modified Eco-scale awarded a score of 70. The Complementary Green Analytical Procedure Index (Complex GAPI) confirmed the method environmentally friendly profile. Additionally, The AGREE tool generated a score of 0.77, indicating strong overall greenness, while the AGREEprep tool, focused on sample preparation, yielded a score of 0.54. Other tools such as the Sample Preparation Metric of Sustainability (SPMS) and the HPLC Environmental Assessment Tool (HPLC-EAT) scored 8.42 and 569, respectively, further demonstrating the method green credentials. This robust and environmentally conscious analytical framework offers significant potential for application in quality control of BEM.

Automated three-step solid-phase extraction of toxicologically relevant psychotropic compounds and metabolites from plasma followed by LC-MS/MS analysis

This study describes a method for the quantification of multiple toxicologically relevant compounds in plasma samples from suicide attempt patients using an automated three-step solid-phase extraction (SPE) with hydrophilic-lipophilic balance (HLB®) sorbent, with subsequent analysis by liquid chromatography-tandem mass spectrometry (LC/MS-MS). This novel approach simplifies the standard five-step SPE process by eliminating the conditioning and equilibration steps. Target analytes included amitriptyline, amphetamine, benzoylecgonine, carbamazepine, cocaethylene, cocaine, codeine, diazepam, fluoxetine, 3,4-methylenedioxymethamphetamine (MDMA), N-methyldiethanolamine (MDEA), methylenedioxyamphetamine (MDA), methamphetamine, morphine, nortriptyline, paroxetine, sertraline, and venlafaxine. Plasma samples (100 µL) were diluted with 4 % phosphoric acid in water, mixed with deuterated internal standards, and subjected to automated SPE using an ASPEC® automation. Analysis was performed using an octadecyl column (1.8 µm, 150 × 2.1 mm) with a 15-minute chromatographic run. The automated SPE took 24 min per sample. Intra-assay precision was 1.6–10.1 %, inter-assay precision was 1.5–5.8 %, and accuracy was 94.4 %–106.6 %. Extraction yields varied from 14.6 % to 78.7 %, with matrix effects ranging from −15.9 % to 13.3 %. The validated method was applied to samples from 50 suicide attempt patients, of which 28 contained quantifiable amounts of the target substances. This study describes the first application of an automated three-step SPE procedure for the extraction of multiple relevant analytes in emergency toxicology

Synergistic extraction of zinc from spent acid using P507-P204: A novel approach for efficient separation

A novel system for the synergistic extraction of zinc from spent acid using a mixture of 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507) and Di-2-ethylhexyl phosphoric acid (P204) as extractant is proposed. The optimum extraction parameters of P507-P204 are investigated, and the results exhibit that 84.80% of zinc is extracted at a solution pH control of 1, the V(P507):V(P204) of 4:1, the P507-P204 concentration of 30% (v/v), and the phase ratio (O/A) of 2:1. Furthermore, the zinc can be effectively stripped from its extracted complex by sulfuric acid. The synergistic extraction mechanism of P507-P204 is identified by slope analysis, FT-IR, mass spectrum, and 31P-NMR. In addition, the mechanism of synergistic extraction of zinc by P507-P204 is cation exchange and releases two hydrogen ions during zinc extraction. In a word, the establishment of this synergistic system realizes the effective separation of zinc from spent acid and has potential industrial application value.

Brønsted‐Acid Catalyzed Diastereo‐ and Enantioselective Synthesis of Spiroisoindolinones from Enamides

A highly stereoselective Brønsted‐acid catalyzed synthesis of densely substituted spiroisoindolinones from enamides and 3‐hydroxy‐isoindolinones is described. With simple Brønsted‐acids, such as para‐toluene sulfonic acid, spiroisoindolinones with three contiguous stereogenic centers are formed in high yields (up to 97%) and diastereoselectivities (up to > 98:<2:0:0 dr) under mild reaction conditions. With the use of a chiral phosphoric acid catalyst, a diastereo‐ and enantioselective synthesis of the corresponding spiroisoindolinones was achieved. Mechanistic investigations indicate a step‐wise mechanism via an initial addition of the enamide to an electrophilic N‐acylimine species followed by an intramolecular aza‐Friedel‐Crafts reaction. Addition of a strong Lewis acid can be used facilitate the second step for less reactive substrates.

Modified sorbents based on natural mineral and its mechanical properties

The use of modified sorbents based on natural minerals, widely distributed in Kazakhstan, is a promising direction. This direction is related to the development of domestic ion-exchange materials. The republic lacks its own production of synthetic sorbents. The environmental situation in the regions of uranium ore mining and processing is also important. Moreover, the application of synthetic sorbents is not always justified due to their high cost, while the use of natural sorbents is limited by their low sorption capacity. The development of modified ion-exchange materials based on a combination of these is a pressing issue for various industries. Research has been conducted on the choice of modification methods for natural sorbents and the evaluation of their sorption capacity after modification. The modification of natural minerals zeolite and shungite using the "solid-phase extractants" method was carried out in two stages. At the first stage, the modification was performed with organic extractants and compositions based on them, and at the second stage with phosphoric acid in combination with polyacrylamide. The natural sorbents used were zeolite from the Kusmuryn deposit and shungite from the Koksu deposit, following preliminary flotation. The mechanical strength of sorbents modified by different methods was compared with the original ion-exchange materials. Studies of the sorption process have shown that the best results for uranium sorption were obtained with modified sorbents: zeolite modified with a mixture of extractants Di-2-Ethylhexyl phosphoric acid (Di-2-EHPA), Tributyl phosphate (TBP), kerosene, and shungite modified with phosphoric acid in the presence of Polyacrylamide (PAA).

Bacillus velezensis SS-20 as a potential and efficient multifunctional agent in biocontrol, saline-alkaline tolerance, and plant-growth promotion

The versatile strain Bacillus velezensis SS-20 was studied to determine its agricultural benefits, including its ability to antagonize fungi, promote plant growth, and tolerate saline-alkaline conditions. Firstly, strain SS-20 was found to be an antagonist of plant pathogenic fungi such as Magnaporthe oryzae, Rhizoctonia solani, and Fusarium oxysporum, with control effects up to 82.07 %, 46.57 %, and 23.09 %, respectively. The hyphae of pathogenic fungi treated with SS-20 and its fermentation product were abnormal, swollen, deformed, and distorted. Meanwhile, strain SS-20 dissolved inorganic phosphorus (phosphate solubilization efficiency, 45.95 %), and produced siderophore (siderophore units, 54.18 ± 4.19 %), and poly-γ-glutamic acid (γ-PGA) (13.35 ± 2.61 g/L). Strain SS-20 significantly increased plant height, aboveground fresh weight, and root dehydrogenase activity compared to the control treatment under non-saline conditions (p < 0.05). In addition, strain SS-20 showed significant saline-alkaline tolerance, surviving in 10 % NaCl and pH 9.5, and enhanced plant growth under simulated saline-alkali conditions. Whole-genome sequencing analysis revealed that the chromosome of B. velezensis SS-20 consists of 3,929,792-bp with 46.5 % guanine-cytosine content and 4015 coding sequences. The antiSMASH analysis identified 12 gene clusters within strain SS-20 that encode antimicrobial compounds such as surfactin, fengycin, butirosin A/butirosin B, macrolactin H, bacillibactin, difficidin, and bacilysin, thereby corroborating the strain's biocontrol capabilities. Genes related to plant growth promotion, including siderophores, γ-PGA, indole acetic acid production, phosphate solubilization, glycine-betaine production, and Na+/H+ antiporters, were also annotated. In conclusion, B. velezensis SS-20 represents a promising biotic resource for enhancing plant growth and protecting against environmental stresses.

Separation of Rare-Earth Elements by Synergistic Mixtures of Methyl(tri-n-Octyl)ammonium Nitrate and an Ammonium Di(2-Ethylhexyl)phosphoric Acid Salt

Separation of Rare-Earth Elements by Synergistic Mixtures of Methyl(tri-n-Octyl)ammonium Nitrate and an Ammonium Di(2-Ethylhexyl)phosphoric Acid Salt

Innovative synergistic extraction of copper(II) from sulfate solutions using D2EHPA and Tri-n-octylphosphine oxide

Solvent extraction is a critical process in the copper extraction industry, offering an advanced method for separating and purifying copper from its ores. As industries aim for increased efficiency and sustainability, the significance of enhancing copper extraction methods is increasingly evident. The liquid-liquid extraction of copper(II) from sulphate medium with di(2-ethylhexy1) phosphoric acid (D2EHPA, HL) has been investigated in chloroform and 1-octanol at 25°C. The study examined the impact on several factors, including the equilibrium pH, extractant concentration, and the nature of diluent. The extracted copper(II) species were found to be CuL2.2HL in chloroform and CuL2 in 1-octanol and the extraction constants of these species were also estimated. The effect of the presence of tri-n-octyl phosphine oxide (TOPO) on the above extraction systems was also studied. A strong antagonistic effect observed during the extraction of copper(II), in the chloroform system is caused by a D2EHPA–TOPO interaction. In the 1-octanol system, the presence of TOPO may change the reaction stoichiometry of copper(II) and D2EHPA.

Anodic Oxide Films Grown in Dehydrated Phosphate/Glycerol Electrolytes at High Temperatures.

Traditional anodization was generally conducted in aqueous or water-containing solutions at room temperature or even lower temperatures. The two best known examples of the application of traditional anodization in the fabrication of nanostructured oxides are porous anodic alumina and titania nanotube films. In 1998, Melody et al. first observed that anodic oxide films on some valve metals such as tantalum can continue to grow at low anodization voltages in phosphate/glycerol solutions containing less than 0.1% water at elevated temperatures (>150 °C) in a non-thickness-limited (NTL) manner. Clearly, this type of anodization at high temperatures is conceptually different from traditional anodization. This Perspective provides a relatively thorough review of this topic. Particular attention is given to the main features for the NTL growth of anodic oxide films and the mechanism behind this behavior. The anodization behaviors for the NTL growth and typical microscopic morphologies of the resultant films on various metals are discussed. The main applications of the attained anodic films with different nanostructures and anodization in other dehydrated electrolyte systems such as the molten orthophosphoric acid are also involved. Finally, we highlight some unresolved issues for this type of anodization at high temperatures and the potential future directions of this field.

Macro-Superlubricity Induced by Tribocatalysis of High-Entropy Ceramics.

Macroscale superlubricity has attracted considerable attention as a promising strategy to minimize frictional energy dissipation and achieve near-zero wear. However, realizing macroscale superlubricity with prolonged durability remains an immense challenge, particularly on engineering steels. Current superlubricants render steel surfaces susceptible to corrosion, causing severe wear and superlubrication failure. Herein, high-entropy ceramics (HEC) with catalytic properties are innovatively introduced to prevent corrosion of engineering steels and achieve macro-superlubricity through tribo-catalytic effect. Furthermore, this catalytically induced superlubricity system exhibits an ultra-low friction coefficient of 0.0037 under contact pressure up to 1.47 GPa, an ultra-long cycle lifetime of 1.25 × 106 cycles (corresponding sliding distance up to 5 km), and an extremely low wear rate of 3.032 × 10-10 mm3·N-1·m-1 on the HEC surface. Based on the experimental analysis and theoretical simulation, the in situ formed HEC nanocrystals reduce the Gibbs free energy of hydrolysis of PA molecules into inositol and phosphoric acid molecules in the lubricant. Notably, the hydrolysis products favorably contributed to the reduction of shear force in the lubrication system, which is essential for achieving macroscale superlubricity over a long time. This study provides a new perspective for designing robust superlubricity systems by harnessing the tribocatalytic effect of high-entropy materials.

The Future of Phosphoric Acid Production -Why We Have to Leave Trodden Paths.

This paper examines the need for innovation in phosphorus fertilizer production. An important area requiring action is the use of sulfuric acid in the wet chemical process (WCP), which is the dominant process in phosphate fertilizer production. About 50 % of the sulfuric acid produced worldwide is used for fertilizers, and ~95 % of the world's fertilizers are based on sulfuric acid. The latter is almost exclusively a by-product of gas and oil production, so the production of conventional P fertilizer is largely dependent on the availability of oil and gas. In addition to rendering P fertilizer production independent of fossil raw materials, energy consumption, CO2 emissions, phosphogypsum production and water consumption should also be considered. With the example of the PARFORCE process and the Improved Hard Process (IHP), new non-sulfuric acid-based alternatives are discussed with respect to overcoming the drawbacks of the classical WCP by being completely independent of fossil sources, working with renewable energies as the sole energy source, and the option of using seawater instead of fresh water. These new processes adhere to the principles of climate neutrality, zero waste production, low CO2 footprint, water conservation, renewable energy use, and energy and resource efficiency. This demonstrates what sustainable innovation can look like from a production perspective. The discussion will focus on whether current incentives are sufficient to realize the sustainability innovations discussed.

Novel guanidinium functionalized poly(pentafluorostyrene): Synthesis and application as ion-pair membrane in PA doped HT-PEMFC

Anion exchange membranes based on poly(pentafluorostyrene) (PPFSt) functionalized with tetramethylguanidinium are described in this study. By incorporating flexible thiohexyl groups onto PPFSt followed by functionalization with tetramethylguanidine and its quaternization with dimethylsulfate, free standing anion exchange membranes were fabricated. The resulting membranes were doped in phosphoric acid (PA) and applied for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The 60 % thiohexylated and 40 % tetramethylguanidinium-functionalized PPFSt membrane (M-PPFSt-TH-TMG) showed higher phosphoric acid doping level (ADL) than meta-PBI (m-PBI) membrane: 13.5 PA/guanidinium to 4.9 PA/imidazole respectively. Conductivity of the M-PPFSt-TH-TMG membrane displayed 322 mS cm−1 (ADL 13.5) and is therefore higher than the one of m-PBI membrane showing 203 mS cm−1 (ADL 4.5) at 160 °C. The fuel cell performance was measured at 160 °C with non-humidified gases and without back pressure on both anode and cathode sides and compared with commercial MEA (Celtec-P 1100W). A PA doped M-PPFSt-TH-TMG MEA showed higher performance than the commercial one exhibiting 793 and 656 mW cm−2 respectively measured under the same condition. The highest performance was obtained with the membrane M-PPFSt-TH-TMG: this membrane showed a peak power density of 1.31 W cm−2 in H2/O2 FC at 160 °C with 2 bars of backpressure on both anode and cathode sides. A stability test in FC showed no significant decay running at a constant current density of 217 mA cm−2 at 160 °C with non-humidified gases for 100 h. An accelerated stress test (AST) carried out via thermal cycling between 80 and 160 °C with humidified gases showed rapid decay over the first 20 cycles, followed by stabilization.