Hydrogen Radicals Research Articles

Enantioselective Synthesis of α‐Aryl Ketones by a Cobalt‐Catalyzed Semipinacol Rearrangement

A highly enantioselective cobalt‐catalyzed semipinacol rearrangement of symmetric α,α‐diarylallylic alcohols is disclosed. A chiral cobalt‐salen catalyst generates a highly electrophilic carbocation surrogate following hydrogen atom transfer and radical–polar crossover steps. This methodology provides access to enantioenriched α‐aryl ketones through invertive displacement of a cobalt(IV) complex during 1,2‐aryl migration. A combination of readily available reagents, silane and N‐fluoropyridinium oxidant, are used to confer this type of reactivity. An exploration into the effect of aryl substitution revealed the reaction tolerates para‐ and meta‐halogenated, mildly electron‐rich and electron‐poor aromatic rings with excellent enantioselectivities and yields. The yield of the rearrangement diminished with highly electron‐rich aryl rings whereas very electron‐deficient and ortho‐substituted arenes led to poor enantiocontrol. A Hammett analysis demonstrated the migratory preference for electron‐rich aromatic rings, which is consistent with the intermediacy of a phenonium cation.

Thermal stability of MDM and oxidative decomposition mechanism under the condition of air infiltration: A combined experimental, ReaxFF-MD and DFT study

When siloxanes are used as the working fluids of organic Rankine cycle systems, there is a possibility of air infiltration due to the large vacuum present in the condenser. To address this issue, experimental and simulation studies were conducted on the thermal stability and pyrolysis product characteristics of octamethyltrisiloxane (MDM) in the presence of air. The results indicated that air significantly promotes the decomposition of MDM at the temperatures above 250 °C. Air was helpful in increasing the formation of CH2O, CO, and CO2, and also enhanced polymerization of decomposition product of siloxane, leading to higher yields of MD2M, MD3M, MD4M, D3, D4, and D5. By combining reactive force field molecular dynamics (ReaxFF-MD) simulations with density functional theory (DFT) calculations, the microscopic mechanisms of MDM's oxidative decomposition by O2 in air and H2O under humid conditions were elucidated. O2 can easily combine with unsaturated Si atoms to form Si-O bonds, combine with CH3 radicals to form C-O bonds, and undergoes hydrogen extraction reactions to initiate decomposition. H2O mainly undergoes initial decomposition through CH3 radical hydrogenation and binding with unsaturated Si atoms. The generated O2H, O, and OH radicals tend to bind with Si atoms in molecules and radicals, facilitating polymerization reactions.

Exploring antioxidative properties of xanthohumol and isoxanthohumol: An integrated experimental and computational approach with isoxanthohumol pKa determination

This study explores the antioxidative activities of xanthohumol (XN) and isoxanthohumol (IXN), prenylated flavonoids from Humulus lupulus (family Cannabaceae), utilizing the oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays along with computational Density Functional Theory methods. Experimentally, XN demonstrated significantly higher antioxidative capacities than IXN. Moreover, we determined IXN pKa values using the UV/Vis spectrophotometric method for the first time, facilitating its accurate computational modeling under physiological conditions. Through a thermodynamic approach, XN was found to efficiently scavenge HOO• and CH3O• radicals via Hydrogen Atom Transfer (HAT) and Radical Adduct Formation (RAF) mechanisms, while CH3OO• scavenging was feasible only through the HAT pathway. IXN exhibited its best antioxidative activity against CH3O• via both HAT and RAF mechanisms and could also scavenge HOO• through RAF. Both Single Electron Transfer (SET) and Sequential Proton Loss-Electron Transfer (SPLET) mechanisms were thermodynamically unfavorable for all radicals and both compounds.

Large-scale floating polyacrylonitrile hybrid micro-/nanofiber membrane achieves efficient H/D isotope separation via photocatalytic proton transport

Advancements in isotope separation are both essential and challenging. The separation of water isotopes is vital in industrial production, biopharmaceuticals, and healthcare applications. This process is energy-intensive and complex due to the similarity of the isotopes. Pure polyacrylonitrile (PAN) is resistant to proton permeability, but neutral hydrogen radicals are capable of penetration. In this study, we report a novel approach using PAN macroscopic hybrid micro-/nanofibers in combination with a photocatalyst to separate hydrogen ion isotopes. Application of photocatalytic water splitting to generate protons results in significantly slower deuteron permeation in these fibers relative to protons, resulting in a separation factor of approximately 15 at room temperature. The composite PAN fibers exhibit a conductivity of 17.5 mS cm−1 at 25 °C and 95 % relative humidity. Our approach not only converts sunlight directly into storable hydrogen, but also enriches heavy water from H₂O/D₂O by H/D isotope separation. This study provides new insights into proton transport mechanisms in acidic media and demonstrates the significant potential of high molecular weight polymers for hydrogen isotope separation.

Bifunctional 0D carbon quantum dot cathode electrocatalyst coupled with atomic hydrogen and hydroxyl radicals for efficient removal of oxytetracycline hydrochloride

Efficient removal of antibiotics is difficult to achieve by conventional single-oxidation or reduction processes. Herein, a bifunctional cathodic electrocatalyst coupling atomic hydrogen (H*) reduction with hydroxyl radical (·OH) oxidation in an efficient electrocatalytic process was developed for the effective degradation of oxytetracycline hydrochloride (OTC). Pd particles were dispersed on B-doped carbon quantum dots to prepare a Pd-B-doped carbon quantum dots/titanium (Pd-BCQD/Ti) electrode as a bifunctional cathode catalyst. The electrode can simultaneously generate H* through the H2O/H+ reduction process, H2O2 through the oxygen reduction process, and then generate ·OH. H* performs nucleophilic hydrogenation reduction of OTC molecules, and ·OH performs electrophilic oxidation of the carbon skeleton, and both act synergistically with the active chlorine species (HClO) generated at the anode. The experimental results showed that the electrode achieved 90.50 % removal of OTC within 60 min. In addition, the Pd-BCQD/Ti electrode reduces energy consumption while increasing current efficiency. The degradation effect was more than 85.80 % in the pH range of 3∼9, indicating fairly stable catalytic activity over a wide pH range. The degradation efficiency was basically unchanged after ten cycles, and the reactivity was still high in the actual water. Intermediates were analyzed based on LC-MS to explore the degradation pathways of OTC. The toxicity of the intermediates generated during OTC degradation was predicted based on quantitative conformational relationships. This study provides a feasible strategy for the preparation of bifunctional catalysts based on zero-dimensional BCQD for efficient green antibiotic wastewater treatment.

Characterisation and biological activities of synthesised copper oxide nanoparticles from the Pimpinella anisum L. aqueous extract

AbstractNanoparticles can be synthesised by several methods. Due to the long duration, high cost, and toxic by-products of chemical and physical methods, the biological method has become more preferred. Among various sources such as bacteria, fungi, or yeast, the use of plants in biological synthesis has proven to be the most ideal. Many metals can be used in the biological method, including copper oxide (CuO). In this study, copper oxide nanoparticles (CuONPs) were synthesised using Pimpinella anisum L. aqueous extract. For characterisation of the CuONPs, UV–Visible Spectroscopy (UV–Vis), Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FT-IR) analyses were performed. The biological activity of the P. anisum extract and CuONPs was determined using DNA cleavage (agarose gel electrophoresis), antioxidant (1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and hydrogen peroxide scavenging activity), mutagenic (Ames/Salmonella test), and catalytic (methylene blue degradation) activities. In DNA cleavage activity test, CuONPs completely denatured DNA at high concentrations (100 and 200 μg mL−1) due to their oxidative activity. The results showed that both the extract and CuONPs have antioxidant properties in DPPH and hydrogen peroxide scavenging activities. According to the mutagenicity, CuONPs did not have a mutagenic effect. In catalytic activity, CuONPs degraded methylene blue within 240 min by 99.45%.

Stretchable conductive shape-memory nanocomposites for programmable electronics via photo-mediated multiscale structural design

Conductive shape-memory nanocomposites are very promising in flexible electronics, soft robotics, wearable sensors, etc. However, achieving a balance between conductivity, shape-memory behavior, and stretchability is still challenging in this field. Here, we report stretchable conductive shape-memory nanocomposites (SCSMNCs) prepared through photo-mediated multiscale structural design (PMMSD). At a molecular level, we utilize highly efficient photo-mediated radical polymerization and hydrogen abstraction reaction to fast construct a conjoined polymeric network in one step (∼68 s). Hybrid nanofibers are, meanwhile, introduced to generate highly conductive networks. This rational design facilitates the fabrication of nanocomposites simultaneously exhibiting excellent shape-memory behavior, high conductivity, improved mechanical properties, and rapid gelation. Mechanics-guided metamaterial design can be then produced in macro-scale by additive manufacturing to further increase the stretchability of the nanocomposites without compromising other key properties. Consequently, benefitting from the PMMSD strategy, the stretching strain of SCSMNCs improves significantly by 19 times compared to the samples lacking network and structural design, with conductivity > 105 S/m, shape fixation ratio and shape recovery ratio > 95 %. Notably, the combination of the increased stretchability, high conductivity and excellent shape-memory behavior endows the SCSMNCs with adaptive electrical and mechanical properties over long ranges. Based on these advanced performances, we demonstrate the utility of the designed SCSMNCs as function-programmable electromagnetic interference shields and wearable sensors. We anticipate this study will pave a new way for the design and application of high-performance SCSMNCs.

Thermal Runaway Characteristics of Ni-Rich Lithium-Ion Batteries Employing Triphenyl Phosphate-Based Electrolytes

Abstract Enhancing the safety performance of high-energy-density lithium-ion batteries is crucial for their widespread adoption. Herein, a cost-effective and highly efficient electrolyte additive, triphenyl phosphate (TPP), demonstrates flame-retardant properties by scavenging hydrogen radicals in the flame, thereby inhibiting chain reactions and flame propagation to enhance the safety performance of graphite/LiNi0.8Co0.1Mn0.1O2 (Gr/NCM811) pouch cells. The results reveal that the capacity retention of cells without flame retardants, and those with the addition of 1 wt%, 3 wt%, 5 wt%, and 10 wt% TPP is 96.4%, 92.1%, 84.15%, 40.8%, and 12.4% (at 1/2C 300 cycles), respectively. Furthermore, compared to cells without flame retardants, the highest temperature during thermal runaway (TR) decreases by 8.3%, 26.9%, 35.1%, and 38.8% with the addition of 1 wt%, 3 wt%, 5 wt%, and 10 wt% TPP, respectively. Through comprehensive analysis of the impact of flame-retardant additives on battery electrochemical performance and safety, it is determined that the optimal addition amount is 3 wt%. At this level, there are no significant flames during battery abuse, the triggering temperature for TR increases by 26.6 ℃, and the maximum temperature decreases by 157 ℃. Moreover, even after 300 cycles at 1/2C, a capacity of 814.5 mAh is retained, with a capacity retention rate of 84.1%. This study provides valuable insights into mitigating TR in high-energy-density power batteries.

Density functional theory and ReaxFF MD study on steam-induced nitrogen migration mechanism during char gasification

The formation of nitrogen-containing species during char gasification is crucial for emission of nitrogenous pollutants. In this work, the detailed nitrogen migration mechanism during char gasification is studied. Density functional theory (DFT) coupled with ReaxFF MD methods are used to conduct an in-depth analysis on the intrinsic reaction mechanism during Char(N) and steam interaction. DFT results show that orbital electrons of carbon atoms on char surface are driven towards nitrogen atoms by nitrogen functional groups. The electron density of adjacent carbon atoms is weakened, which has a positive charge. Orbital electron properties show that the band energy gaps of three Char(N) models are 3.063 eV, 1.092 eV and 3.328 eV, indicating the reactivity order for three Char(N) models is as follows: Char(N)-2＞Char(N)-1＞Char(N)-3. DFT calculation indicates that the interaction between Char(N) and steam reduces unsaturated carbon atoms and lower the char decomposition activity, which will inhibit the yield of HCN. In contrast, through hydrogen transfer reactions, nitrogen atoms are easily combined with hydrogen atoms, which is more conducive to the formation of ammonia. ReaxFF MD modeling proves that HCN is the main product for Char(N) decomposition under inert atmosphere. Under steam atmosphere, nitrogen atoms in char are more likely to be converted into amino products. The induction of steam provides a large number of active hydrogen radicals, which is able to attack the nitrogen atoms of char and form N–H bonds, thus promoting the formation of ammonia.

Cyanobacterial Phycocyanin-Based Electrochemical Biosensor for the Detection of the Free Radical Hydrogen Peroxide.

Cyanobacteria are photosynthetic prokaryotes that inhabit extreme environments by modifying their photosensitive chemoreceptors called cyanobacteriochromes (CBCRs) which are linear tetrapyrrole-linked phycobilin molecules. These light-sensitive phycobilin from Spirulina platensis is recognized as a potential photoreceptor tool in optogenetics for monitoring cellular morphogenesis. We prepared and extracted highly fluorescent cyanobacterial phycocyanin (C-PC) by irradiating the culture with ambient red light. The crude phycocyanin was subjected to ion exchange chromatography, and its purity was monitored using UV-visible, fluorescence, and FT-IR spectroscopy methods. In the conventional method, red light-induced C-PC exhibited strong antioxidant activity against H2O2, with 88.7% in vitro scavenging activity without requiring any other preservatives. Interestingly, this red light-acclimated phycocyanin was applied as a biosensing material for the detection of the free radical hydrogen peroxide (H2O2) using the enzyme horseradish peroxidase (HRP) as a mediator. The modified C-PC-HRP glassy carbon electrode (GCE) can detect H2O2 from 0.1 to 1600µM. The lowest possible detection limit of the electrode for H2O2 was 19nM. This electrode was used to detect free radical H2O2 in blood serum samples. The microstructure of the lyophilized PC under SEM showed a flat crystal pattern, which enabled the immobilization of HRP on the electrode surface and electron transfer.

Metal‐ and Photocatalyst‐Free Aerobic Photoinduced Benzyl C(sp3)−H Bonds Oxidation

AbstractPhotoinduced the direct oxidation of benzyl C(sp3)−H bonds provides an attractive strategy for producing high‐value chemicals or intermediates. Unlike the conventional approaches that typically require transition‐metal catalysts, semiconductors, and organic photosensitizers as the photocatalysts, herein we report a bromine salt‐promoted photoinduced aerobic oxidation protocol for methylarenes. By applying NH4Br as both the bromine radical source and hydrogen atom transfer agent, photoinduced oxidation of methylarenes to the corresponding carboxylic products exhibits high conversion and selectivity. Furthermore, control experiments confirm that reactive oxygen species are proved to be essential for the success of this transformation. This strategy provides a metal‐/strong oxidant‐/photocatalyst‐free paradigm for the direct deep oxidation of methylarenes.

Recovering high-quality glass fibers from end-of-life wind turbine blades through swelling-assisted low-temperature pyrolysis

The recycling of end-of-life wind turbine blades has become a global environmental challenge driven by the rapid growth of wind power. Pyrolysis is a promising method for recovering glass fibers from these discarded blades, but traditional pyrolysis is often operated at high temperatures, which degrades the mechanical properties of recovered fibers. To address this issue, a swelling-assisted pyrolysis method was proposed to recover high-quality glass fibers from end-of-life wind turbine blades at low temperatures. The results confirmed that the decomposition of the resin matrix within the blade was significantly promoted at low temperatures in the swelling-assisted pyrolysis process, achieving a resin decomposition ratio of 76.8 % at 350 °C. This improvement was attributed to enhanced heat transfer and co-pyrolysis with acetic acid. Swelling could physically disrupt the cross-linked structure of the blade, creating a more porous and layered structure, thereby enhancing heat transfer during the pyrolysis process. Simultaneously, the co-pyrolysis with acetic acid could generate hydrogen radicals, which promoted the cracking of macromolecular oligomers into lighter products or gaseous alkanes. Consequently, the formation of pyrolysis char within the solid pyrolysis product was reduced, shortening the oxidation duration to 30 min. In comparison to traditional pyrolysis, the swelling-assisted pyrolysis process effectively suppressed the diffusion of surface defects over the recovered fibers, leading to promising improvements in their flexibility, elasticity, and mechanical properties, with tensile strength notably increased by 27.5 %. These findings provided valuable insights into recovering high-quality glass fibers from end-of-life wind turbine blades.

Fixed-node diffusion Monte Carlo shows promise for modeling reaction thermochemistry of hydrocarbon-based radicals.

Reliable thermodynamic and kinetic properties of free radical polymerization reactions are essential for synthesizing both primary polymeric materials and specialty polymers. The computational generation of these data from quantum chemistry requires a time-efficient method capable of capturing the essential physics. One such method, fixed-node diffusion Monte Carlo (FN-DMC) (using single Slater-Jastrow trial wavefunctions), has demonstrated the capability to recover 90%-95% of missing dynamic correlation energy for typical systems. In this study, methyl radical addition to ethylene serves as a simple model to test FN-DMC's ability to calculate enthalpies of reaction and activation energies with different time steps, antisymmetric trial wavefunctions, basis set sizes, and effective core potentials. The FN-DMC computational protocol thus defined for methyl radical addition to ethylene is subsequently benchmarked against Weizmann-1 and experimental reaction enthalpies from Lin et al.'s test set of 21 radical addition and 28 hydrogen abstraction enthalpies. Our findings reveal that FN-DMC consistently generates reaction enthalpies with chemical accuracy, exhibiting mean absolute deviation of 3.5(7) and 1.4(8) kJ/mol from the Weizmann-1 reference for radical addition and hydrogen abstraction reactions, respectively. Given its favorable computational scaling and high degree of parallelizability, we, therefore, recommend more comprehensive testing of FN-DMC with effective core potentials to address more extensive and intricate polymerization reactions and reactions with other radicals.

Energy-Transfer Enabled Divergent Synthesis of Polycyclic γ-Sultines.

A visible-light-initiated energy-transfer enabled radical cyclization for the divergent synthesis of polycyclic γ-sultine derivatives has been developed. The reaction provides an alternative and expeditious access to benzofused γ-sultine frameworks, the analogues of γ-lactones and γ-sultones, and features good functional group compatibility, mild reaction conditions and excellent diastereoselectivity. The robustness and application potential of this method have also been successfully displayed by two gram-scale reactions and the synthesis of polycyclic sultones. Mechanistic studies indicated the transformations through a possible energy-transfer enabled intramolecular radical homolytic substitution or hydrogen atom transfer process mainly.

MgAl hydrotalcite supported ultrafine PdNi bimetallic catalyst for the dehydrogenation of dodecahydro-N-ethylcarbazole

Liquid organic hydrogen storage is a promising way of storing hydrogen. The development of efficient and low-cost dehydrogenation catalysts is still required to advance the commercialization of N-ethylcarbazole/dodecahydro-N-ethylcarbazole (NEC/H12-NEC) hydrogen storage and transport system.In this paper, PdNi bimetallic catalyst (Pd3Ni1/LDHs) supported on MgAl hydrotalcite was prepared by NaBH4 and ultrasound-assisted stepwise reduction. Ultrasonic cavitation could excite the hydroxyl hydrogen of hydrotalcite in the form of hydrogen radicals to reduce PdCl42− to Pd nanoparticles (NPs), and also promoted the formation of PdNi alloys as well as the dispersion of NPs. In the Pd3Ni1/LDHs catalyst, the average particle size of NPs was 1.98 nm, suggesting an excellent dispersion of Pd, Ni, and PdNi NPs. The electronic effects of Ni and Pd significantly improved the catalytic efficiency of Pd3Ni1/LDHs in H12-NEC dehydrogenation, resulting in a hydrogen release rate of 98.4 % after 6 h at 180 °C, surpassing that of Pd/LDHs. It can be considered that the dehydrogenation performance of Pd3Ni1/LDHs for H12-NEC is related to the alloy phase, electronic structure and NPs size.

Environmental fate of phenobarbital in water: Homogeneous and non-homogeneous environment

In aqueous environments, phenobarbital (PB) undergoes degradation mediated by hydroxyl radicals (HO·) and sulfate radicals (SO4·−). In this study, a theoretical approach was used to investigate the oxidation of phenobarbital triggered by HO·/SO4·− in different dissociated forms of PB at different pH values, as well as the adsorption mechanism of phenobarbital on the silica surface and the non-homogeneous reaction with HO·. Our study confirms three primary reaction models for PB degradation: radical addition, hydrogen abstraction, and single electron transfer reactions. Thermodynamic and kinetic calculations show that the reaction of PB with HO· is the main degradation pathway compared to the reaction of SO4−. At the C5 and C6 positions, HO·-addition and H-abstraction from H6 and H7 are competitive mechanisms. However, in non-homogeneous environments, HO·-addition at C5 becomes the dominant pathway. Our work identifies the primary products of these degradation reactions. At a temperature of 298 K, the total rate constants for the degradation reactions of HO· with PB neutral molecules and anions were determined to be 2.06 M−1 s−1 and 4.11 × 107 M−1 s−1, respectively. In a non-homogeneous reaction with HO·, the total rate constant is 4.47 × 1010 M−1 s−1. Despite degradation, the majority of these products retain their potential to impact aquatic organisms. In particular, compounds such as 5-ethyl-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione, 5-(1-hydroxyethyl)-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trione, and 5-acetyl-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trione have a greater toxic effect on green algae. The findings underscore the need for future research to consider the environmental implications and ecotoxicity of PB. Such consideration is crucial for a comprehensive understanding of the long-term environmental impact of pharmaceutical residues in aquatic ecosystems.

Влияние фитохимического и антиоксидантного составов необработанных водных экстрактов Chlorella vulgaris на рост Saccharomyces cerevisiae в спиртовой среде

Chlorella vulgaris is rich in secondary metabolites that defend against environmental stress and aid in detoxification. In particular, bioactive compounds extracted from C. vulgaris may enhance the growth of microorganisms and detoxify them in an ethanolic medium. We aimed to effectively extract and characterize bioactive compounds found in C. vulgaris and further test them for their beneficial effects on the growth of Saccharomyces cerevisiae cultured in an ethanolic medium. Bioactive compounds in C. vulgaris were extracted using ultrasound and water as solvents. The extracts were analyzed for total phenol and flavonoid contents as part of their phytochemical composition. Their DPPH radical activity and Hydrogen peroxide scavenging activity were examined to determine their antioxidant properties and protective potential for S. cerevisiae in an ethanolic medium. Further, the extracts were added at 0.1, 0.5, 1, 2, 3, and 4% w/v concentrations into S. cerevisiae culture induced with 1% v/v ethanol for 23 days. The yeast cells’ density and viability were measured after 2, 5, 9, 13, 17, and 23 days. The extracts of C. vulgaris were rich in phenols and flavonoids, which are important bioactive compounds. Higher concentrations of the extracts increased total phenols up to 47.67 GAE mg/L and total flavonoids up to 218.67 QE mg/L. The extracts’ antioxidant composition showed high DPPH activity (70.12%) and H2O2 scavenging activity (4.97%). After 23 days, the samples treated with C. vulgaris extracts maintained a high viability of the yeast cells. In particular, the samples with 2, 4, 0.1, and 1% of the extract had a cell viability of 95.75, 94.04, 89.15, and 74%, respectively. The positive control (1% ethanol alone) and negative control (yeast alone) had 47.71 and 21.01% viability, respectively. This drastic reduction in viability was due to lysis of the yeast cells caused by ethanol. Ultrasound extraction with water as a solvent produced abundant beneficial secondary metabolites from C. vulgaris. The addition of C. vulgaris extract increased the viability and cell density of S. cerevisiae after 27 days, thereby protecting the yeast cells from the toxic effects of ethanol.

Ethynyl Radical Hydrogen Abstraction Energetics and Kinetics Utilizing High-Level Theory.

The ethynyl radical, C2H, is found in a variety of different environments ranging from interstellar space and planetary atmospheres to playing an important role in the combustion of various alkynes under fuel-rich conditions. Hydrogen-atom abstraction reactions are common for the ethynyl radical in these contrasting environments. In this study, the C2H + HX → C2H2 + X, where HX = HNCO, trans-HONO, cis-HONO, C2H4, and CH3OH, reactions have been investigated at rigorously high levels of theory, including CCSD(T)-F12a/cc-pVTZ-F12. For the stationary points thus located, much higher levels of theory have been used, with basis sets as large as aug-cc-pV5Z and methods up to CCSDT(Q), and core correlation was also included. These molecules were chosen because they can be found in either interstellar or combustion environments. Various additive energy corrections have been included to converge the relative enthalpies of the stationary points to subchemical accuracy (≤0.5 kcal mol-1). Barriers predicted here (2.19 kcal mol-1 for the HNCO reaction and 0.47 kcal mol-1 for C2H4) are significantly lower than previous predictions. Reliable kinetics were acquired over a wide range of temperatures (50-5000 K), which may be useful for future experimental studies of these reactions.

Synthesis of AlPO-18 Zeolite Membrane by Sonication-Assisted Hydrothermal Method for H2 Separation from Blast Furnace Flue Gas

In this study, AlPO-18 zeolite has been synthesized at temperatures ranging from 140° to 180°C and varying synthesis time from 3 to 20 h using sonication mediated hydrothermal process. The characterization results of the synthesized powders and membranes revealed that phase pure AlPO-18 zeolite has been formed at 150°C for 15 h under sonication energy of 250 W. For comparison, the same has been synthesized by the conventional method for 200°C and 69 h. In the sonochemical process, H2O molecule splits into hydrogen radicals (H•) and hydroxyl (•OH) radicals with intense local heating and high pressure during the collapsing of cavitation, which initiates the formation of dihydrogen phosphite (H2PO3•) and dihydrogen phosphate (H2PO4•) radicals and facilitate the formation of AlPO-18 zeolite. Finally, the performance of the membranes has been studied with varying feed pressures for different binary gas mixtures and single gases, and simulated blast furnace (BF) gas has been used to study the separation efficiency of the membranes. The highest separation factors, calculated from BF mixture gas of H2/CO2 and H2/N2 have been achieved as 8.7 and 21, respectively. These results show the possibility of hydrogen recovery from BF flue gas to convert waste to wealth.

In Situ Ambient Pressure Photoelectron Spectroscopy Study of the Plasma-Surface Interaction on Metal Foils.

The plasma-surface interface has sparked interest due to its potential of creating alternative reaction pathways not available in typical gas-surface reactions. Currently, there are a limited number of in situ studies investigating the plasma-surface interface, restricting the development of its application. Here, we report the use of in situ ambient pressure X-ray photoelectron spectroscopy in tandem with an optical spectrometer to characterize the hydrogen plasma's interaction with metal surfaces. Our results demonstrate the possibility to monitor changes on the metal foil surface in situ in a plasma environment. We observed an intermediate state from the metal oxide to an -OH species during the plasma environment, indicative of reactive hydrogen radicals at room temperature. Furthermore, the formation of metal-carbides in the hydrogen plasma environment was detected, a characteristic absent in gas and vacuum environments. These findings illustrate the significance of performing in situ investigations of the plasma-surface interface to better understand and utilize its ability to create reactive environments at low temperature.