Inert Environment Research Articles

Synthesis and characterization of poly indole-iron oxide nanoparticles for biomedical applications

Iron oxide (Fe3O4) nanoparticles (NPs) were synthesized by co-precipitation method, further Fe3O4-NPs was encapsulated under inert environment with poly-indole carboxylic acid, finally the product obtained as poly-indole carboxylate iron oxide nanoparticles(PIFe3O4-NPs). Then, the both products Fe3O4-NPs and PIFe3O4-NPs were characterized and confirmed the composition of elements using X-ray diffraction pattern (XRD). The change in shape and morphology of products was confirmed by scanning electron microscopy (SEM). The functional groups and shifting of vibrational bands due to the coordination of both Fe3O4 and ligand are studied using Fourier transform infrared (FT-IR) spectra. The band gap of the products were measured using Ultraviolet–visible (UV–Vis.) spectra and also measured the direct and indirect band gap using Tauc plot. To investigate the binding nature of the sample, a molecular docking study was carried out and the results indicated that the PIFe3O4 moiety formed five hydrogen bonds with amino acid residues of Aspergillus niger ATCC9642 isopullulanase (2Z8G). The oxygen atom of Fe3O4-NPs binds well with the active sites of Staphylococcus Aureus Protein A (1BDC) and Escherichia Coli thioredoxin reductase (1TDE) with the ASN24, GLY17, ALA16, GLY14, and GLY113 residual interactions. Therefore, the results of molecular docking emphasized that the target Fe3O4-NPs nanoparticles can bind more easily to the target proteins 1BDC, 1TDE, and 2Z8G. In addition to that, antioxidant, antibacterial and antifungal activities were also examined. These findings demonstrate that PIFe3O4-NPs have antimicrobial and antioxidant properties and therefore it confirms the use of PIFe3O4-NPs in the treatment of infection against fungus, gram-positive and gram-negative bacteria.

Enhanced mono-aromatics production by the CH4-assisted pyrolysis of microalgae using Zn-based HZSM-5 catalysts

This study presents the catalytic pyrolysis of microalgae, Chlorella vulgaris (C. vulgaris), using pure CH4 and H2-rich gas evolved from CH4 decomposition on three different HZSM-5 catalysts loaded with Zn, Ga, and Pt, aimed specifically at producing high-value mono-aromatics such as benzene, toluene, ethylbenzene, and xylene (BTEX). In comparison with that for the typical inert N2 environment, a pure CH4 environment increased the bio-oil yield from 32.4 wt% to 37.4 wt% probably due to hydrogen and methyl radical insertion in the bio-oil components. Furthermore, the addition of bimetals further increased bio-oil yield. For example, ZnPtHZ led to a bio-oil yield of 47.7 wt% in pure CH4. ZnGaHZ resulted in the maximum BTEX yield (6.68 wt%), which could be explained by CH4 activation, co-aromatization, and hydrodeoxygenation. The BTEX yield could be further increased to 7.62 wt% when pyrolysis was conducted in H2-rich gas evolved from CH4 decomposition over ZnGaHZ, as rates of aromatization and hydrodeoxygenation were relatively high under this condition. This study experimentally validated that the combination of ZnGaHZ and CH4 decomposition synergistically increases BTEX production using C. vulgaris.

Effects of ignition voltage and electrode structure on electric ignition and combustion characteristics of Ammonium Dinitramide (ADN)-based liquid propellants in electric ignition mode in inert gas environment

Hydrazine is toxic and carcinogenic, which greatly increases the difficulty of application and no longer meets the needs of green aerospace. As a green propellant, the Ammonium Dinitramide (ADN)-based liquid propellant has the advantages of higher specific impulse, being non-toxic, pollution-free, and easy storage. However, an ADN-based space engine in orbit has exposed the problems of high-temperature deactivation of catalysts and cold-start failure. An active ignition technology—electric ignition technology was explored in this paper to break through the technical bottleneck of catalyst deactivation and the inability to a cold start. An experimental system of a constant-volume combustor for the ADN-based liquid propellant based on the electric ignition method was established. The electric ignition and combustion characteristics of the ADN-based liquid propellant in a volume combustor with an electric ignition method were studied. The influencing mechanisms of the ignition voltage and the electrode structure on the electric ignition characteristics of the ADN-based liquid propellant were investigated. An elevation of the ignition voltage could facilitate the ignition process of the ADN-based liquid propellant, curtail electric energy input and heating effect, while exerting an adverse impact on the combustion process of the propellant. An increase in the ignition voltage enhanced the ignition process of the propellant while simultaneously suppressing its combustion process when utilizing mesh electrodes. Compared to the strip electrodes, the mesh electrodes increased the contact area between the electrodes and the propellant, increased the electric energy input power in the electric ignition process, and reduced the ignition delay time. The mesh electrodes could promote the combustion process of the propellant to a certain extent.

Experimental testing of Ti-6Al-4V under axial cyclic loading

The Ti-6Al-4V titanium alloy is commonly used in the manufacturing of aircraft components. These components are typically subjected to cyclic stresses during their operational life. The propagation of existing defects contributes to fatigue degradation, making a comprehensive study of the fatigue response of Ti-6Al-4V containing defects crucial for an accurate evaluation of component durability. This paper presents the outcomes of experiments conducted in an inert environment using smooth and notched Ti-6Al-4V specimens subjected to axial cyclic loading. The fatigue strength appears comparable among the notched specimens and is significantly higher for the smooth ones. The failure of one of the tested smooth specimens started from a location different from where stress concentration is expected, probably due to the presence of a micro notch.

Characterization of diesel spray with novel high-speed laser absorption scattering technique under diesel engine-like condition

In Diesel Engines, the injection process plays a decisive role in the combustion efficiency. Hence, the characterization of diesel sprays is very important. Several methods are developed, however, none of them records the temporal fuel distribution throughout the individual injection event and measures the liquid/vapor concentration of an evaporating diesel spray. In this work, two light sources i.e., an ultraviolet LED and a continuous wave laser, were used with two high-speed video cameras. A fuel mixture with the compositions of 97.5 % n-tridecane and 2.5 % of volume-based 1-methylnaphthalene was selected as the test fuel. The fuel was intermittently injected into an inert environment at 4.8 MPa and 800 K by applying a seven-hole injector with a hole diameter of 0.123 mm. The injection pressure was set at 100 MPa and the injection amounts were set as 2.5 and 5.0 mg/hole to observe the effect of the injected mass on the spray characteristics and mixture formation process. Calibration, based on the scattering by non-evaporating sprays and molar absorption coefficients for fully evaporated sprays, indicates a measurement error of 15 %. The findings of the experiments show that, under large injection mass conditions, the liquid phase equivalence ratio is quite low and close to zero just after the end of injection which points out that as the air-fuel mixing quality improves, the majority of the liquid fuel is rapidly converted to vapor. The air-fuel mixture is overall richer at large injected mass compared to the small mass condition. Furthermore, after the end of injection, the high fuel vapor concentration area near the nozzle soon mixes with ambient gas, decreasing the equivalence ratio to low levels, whereas a high-vapor-concentration region is still present at the spray head. This study provides a valuable insights into the behavior of the fuel spray, which could be used to improve the efficiency and performance of diesel engines.

EFFECTS OF FLUORINATED AND NON-FLUORINATED ADDITIVES ON BURNING RATES OF BORON-TEFLON BLENDS FOR SOLID ROCKET PROPULSION

Boron is considered a promising metal fuel for energetic propellants due to its high energy density, but in practice, boron experiences slow combustion kinetics. Fluorinated additives can improve boron combustion. The objective of this study was to determine how different fluorinated additives would affect the burn rate of a boron-based fuel in a high-pressure inert environment. Boron powder was sintered with polytetrafluoroethylene (PTFE) powder to create test pellets with variable fluorine:boron mass ratios. Three different purities of boron powders were tested, along with three different fluoropolymer additives and 14 other additives, which varied in molecular morphology and fluorination. The base boron-PTFE test pellets with no additives have a maximum burning rate at fluorine:boron mass ratio of ~ 3.5, which remains the same even with additives at 20 wt%. A commercial fluoropolymer, Aquivion, showed significant burn rate enhancement at 20 wt% but not at 5 wt%. At this lower loading level, materials that tend to enhance thermal conductivity (graphene, nanotubes) show some burn rate enhancement, even without fluorination. However, very significant burn rate enhancement is shown by a fluorinated carbon nanotube, likely due to the reduced bond dissociation energy of fluorine when attached to a nanotube. The data suggest this method of fluorination can have an important effect on enhancing boron combustion, and even small additives with readily available fluorine could significantly improve boron combustion rates for solid propellant applications.

Sintetika i karakterizacija Al-PTFE funkcionalno klasifikovanog materijala primenom tehnike metalurgije praha

The current work involves producing the functionally graded material (Al-PTFE) utilizing the powder metallurgy technique. The proposed graded materials include three, four, and five layers. Each layer consists of PTFE and Al particles with an average diameter of 200nm and 25 micrometers, respectively. The powders were blended, formed into cylindrical shapes, and then sintered in an inert environment furnace. The microstructural and morphological properties of the graded materials are studied using XRD and SEM images. The prepared graded materials' porosity density and hardness are measured experimentally. The results of XRD and SEM images reveal that the FGMs are successfully developed without any separation or crack formation and that PTFE was uniformly dispersed throughout the layers with particle concentrations of 25 and 50 wt%. Al. The obtained results also reveal that the density of various FGMs was comparable to that of PTFE.

Improving the direct air capture capacity of grafted amines via thermal treatment.

This study investigates the effects of elevated temperature thermal treatments on the direct air capture of CO2 by aminosilane-grafted SBA-15 silica sorbents. Exposing samples to high temperatures (200-250 °C compared to 80-120 °C) in an inert environment resulted in improved CO2 capacity (5-21%) that was sustained over multiple adsorption/desorption cycles.

Characterization and evaluation of torrefied sugarcane bagasse to improve the fuel properties

Torrefaction is a promising method of treatment with a prospect toward Physco-chemical improvement and thermal upgrading of biomass. In the present study, the torrefaction of sugarcane bagasse in both dry and chemical treatment in comparison with the physical, chemical, and thermal properties of raw bagasse was investigated. Thermochemical torrefaction was carried out by pretreatment of raw bagasse with dilute sulfuric acid. The torrefaction temperature was carried out at a carried temperature (220–280 °C) and a torrefaction period (30–120 min) in a packed bed reactor under an inert environment, whereas dry torrefaction was performed using the same treatment without the addition of a chemical to the raw bagasse. Chars produced by chemical torrefaction were found with improved properties of heating value, energy, and bulk density at 280 °C and 120 min. Increasing temperature resulting in high fixed carbon content apparently decreases moisture content and volatile matter. The mass yield and energy yield were found to be decreased with temperature and time. The carbon content of torrefied bagasse was increased with temperature and time, whereas, hydrogen and oxygen content decreased due to the devolatilization reactions. It was able to upgrade HHV from 16.05 to 20.34 MJ/Kg in dry and 22.29 MJ/Kg in chemical torrefaction.

Inert-Atmosphere Microfabrication Technology for 2D Materials and Heterostructures.

Most 2D materials are unstable under ambient conditions. Assembly of van der Waals heterostructures in the inert atmosphere of the glove box with ex situ lithography partially solves the problem of device fabrication out of unstable materials. In our paper, we demonstrate an approach to the next-generation inert-atmosphere (nitrogen, <20 ppm oxygen content) fabrication setup, including optical contact mask lithography with a 2 μm resolution, metal evaporation, lift-off and placement of the sample to the cryostat for electric measurements in the same inert atmosphere environment. We consider basic construction principles, budget considerations, and showcase the fabrication and subsequent degradation of black-phosphorous-based structures within weeks. The proposed solutions are surprisingly compact and inexpensive, making them feasible for implementation in numerous 2D materials laboratories.

Investigation of the properties of high-strength fibers by methods of physico-chemical analysis

The carbon fiber (CF) of UMT 49-12K-ER grade, manufactured by Alabuga-Volokno LLC (Umatex JSC), was the subject of an extensive study. This investigation encompassed an analysis of its physico-chemical properties. The interplanar dimensions and chemical composition of the CF were determined using X-ray diffraction and atomic emission spectroscopy. Surface properties of the CF, including specific surface area and pore size distribution, were investigated through nitrogen adsorption. The BET specific surface area was measured at 0.29 m2/g. The volume of mesopores and their size distribution were calculated using the Barrett, Joyner, and Halenda method. Additionally, an analysis of surface functional groups was conducted through a back titration method. It was observed that there was no presence of carboxyl, phenolic, or carbonyl groups. The diffraction patterns were processed with a two-component profile description model. The results of atomic emission spectral analysis revealed that silicon compounds were the dominant impurities in the chemical composition of the CF. Further investigations determined that, in an inert environment, the epoxy coupling agent used to enhance the performance properties of this CF undergoes thermal decomposition at temperatures of 300–400 °C. The CF itself does not experience weight loss when heated up to 950 °C. It was also discovered that this CF ignites in the presence of oxygen at temperatures exceeding 550 °C, surpassing the thresholds noted in previous publications for carbon fibers without such specialized additives. The results of this research have suggested new methodologies for studying carbon fibers.

3D Printed Carbon Framework with the Graphene Aerogel for Microbial Fuel Cell Application

There is a high interest in living organism-compatible materials associated with electrically active interfaces. Bacteria/electrode interfaces implement smart, functional systems with responses, based on which it is possible to elaborate self-regulating energy generation systems. Carbon materials have a number of advantages, such as biocompatibility, low electrical resistance, and the possibility of increasing the electrode surface on an industrial scale. The most promising approach for the industrial production of electrodes is 3D printing. We propose a 3D-printed carbon electrode – a novel lightweight material for electrodes in bioelectrochemical systems for efficient bioelectricity utilization.The pyrolytic process for manufacturing carbon electrodes is promising for upscaling and industrial applications. However, there is a problem of volume loss when 3D-printed polymers are pyrolyzed in an inert environment. We propose a new strategy for the thermal treatment of 3D-printed polymers that allow for reduced volume loss under pyrolytic carbonization. In addition, to achieve a higher electrode surface area, the graphene aerogel could be impregnated into the 3D-printed scaffolds. Chemical modification of graphene surface can enhance biocompatibility. Specifically, the oxidation of graphene leads to forming a hydrophilic and biocompatible material. We tune graphene hydrophilic properties and electrical conductivity via control over the thermal reduction of the oxidized form of graphene–graphene oxide1.Such sponge morphology affords 3D-printed carbon scaffolds an excellent lightweight host scaffold for microorganisms, in which the graphene nanowalls are homogeneously occupied by S. oneidensis MR-1. We demonstrate a novel sustainable method to produce graphene-based lightweight 3D printed electrode materials for green energy production from biomass. The proposed technology creates the opportunity for novel, innovative, disruptive graphene applications that can lead to the establishment of new energy-related industries and facilitate many startups in the ecosystem. Acknowledgments This work was supported by the Ministry of Education (Singapore) through the Research Centre of Excellence program (grant EDUN C-33-18-279-V12, I-FIM). References Xuanye Leng, Ricardo J. Vazquez, Samantha R. McCuskey, Glenn Quek, Yude Su, Konstantin G. Nikolaev, Mariana C.F. Costa, Siyu Chen, Musen Chen, Kou Yang, Jinpei Zhao, Mo Lin, Zhaolong Chen, Guillermo C. Bazan, Kostya S. Novoselov, Daria V. Andreeva, Carbon, 205, 2023, 33-39.

(Invited) Development of Perovskite Photovoltaic Devices Using Electrodeposition

Photovoltaic energy is considered today as the most useful natural energy source. To date, different types of solar technologies are industrially available, and the attempts in research and development to improve their potential are continuing. While a number of different materials with different efficiencies can achieve photovoltaic solar energy conversion, so far, no particular material or combination is cheap enough to compete with large-scale fossil fuel-generated electricity. Nowadays, Si-based cells are the most marketed, and they produce high solar conversion efficiencies. However, expensive high temperature and high vacuum processes are adopted in order to elaborate pure Si. Another active material, called perovskite, newly emerged in the solar community. It has attracted major attention worldwide because of its outstanding photovoltaic performance, easy fabrication process, adaptable band-gap, high extinction coefficient, and high carrier mobility. As perovskite is capable of generating a power conversion efficiency approaching that of the leading silicon and that the solar devices fabrication cost is lower, perovskite solar cells tend to be considered as the future of the photovoltaic technology.However, the most used method to deposit perovskite active layer is spin coating, which presents many constraints such as limited surface coverage, non-homogeneity, undefined perovskite crystallinity, and poor stability. Perovskite obtained by spin-coating requires working in inert environment (glove box) and adding some toxic additives to maintain the stability of the perovskite. This increases its cost and enables the deposition only on small surfaces. There is thus a need to look up for alternative deposition methods, more ecofriendly, at lower costs, applicable for large-scale production of perovskite solar cells.Electrodeposition recently started to be explored as an efficient alternative for perovskite fabrication. There have been several attempts over the past years to optimize the electrodeposited perovskite layer and adjust its crystallization on dissimilar layers. All sub-techniques started by electrodepositing an initial layer (PbO, PbO2 or PbI2) followed by one or several conversions of the as-deposited layer. In the presented work, we were able to develop different types of perovskites using electrodeposition, understand the impact of the different deposition parameters on their structure, and improve their stability comparing to the spin-coated ones. Along with the simple MAPbI3 perovskite, the electrodeposition of mixed MAPbI3-xClx and MA1-yFAyPbI3-xBrx perovskites will be presented. The present study is one of its kind, since these mixed perovskite were never developed using electrodeposition before. It was observed that using electrodeposition afford enhanced stability compared to spin-coating process, and the different fabricated perovskites were also proved to experience a positive maturation phenomenon during their first 500 hours of life.The electrodeposition process is easy to manipulate, and the electrodeposited films could grow on surfaces as large as desired, inside an electrolyte, allowing its application in ambient atmosphere, with no need of a glove box. It is also eco-friendly in terms of solvent engineering, since no toxic solvents are needed to stabilize or enhance the morphology of the obtained films. The main solvents used are deionized water, ethanol and isopropanol.

Probing the Effect of Environments on the Stability of Ni2P Nanoparticle Electrocatalysts

Ni2P has been shown to be an effective catalyst for the hydrogen evolution reaction (HER), making it a promising replacement for Pt which is the current state of the art HER catalyst.1,2 H2 is a clean-energy critical fuel and chemical highlighted by the US Department of Energy’s “Hydrogen Shot,” which seeks to reduce “the cost of carbon-neutral hydrogen by 80% to $1 per 1 kg in 1 decade, highlighting the key role of hydrogen in implementing carbon-neutral solutions.”3 Ni2P is also a good or promising catalyst for other reactions, such as alcohol oxidation, hydrodesulfurization,4,5 nitrate reduction, and oxygen evolution reaction.6 However, Ni2P and other TMPs are susceptible to oxidation, which can lead to catalyst degradation and loss in certain conditions.7,8 Stability is an important part of catalysis, especially for achieving the goals of the Hydrogen Shot. Therefore, it is important to understand complex degradation mechanisms in order to better understand structure-activity relationships in these materials. In the present work, in situ Ni K-edge X-ray absorption spectroscopy (XAS) and ex situ P Kα and Kβ X-ray emission spectroscopy (XES) couple together to understand the degradation of Ni2P and show the effects of electrolyte pH, ligands, and air on Ni2P nanoparticles.5 nm Ni2P nanoparticles were synthesized by heating NiCl2 and tris(diethylamino)phosphine in oleylamine. The nanoparticles were drop cast onto carbon fiber paper electrodes and Si wafers or Au-coated wafers for P Kα and Kβ XES. Oleylamine ligands are removed by thermal annealing. Electrochemical experiments were conducted with a three-electrode cell using carbon fiber paper or Au-coated wafers deposited with Ni2P nanoparticles as working electrode, Ag/AgCl calibrated to the H2 redox couple as reference electrode, and graphite rod as counter electrode. P Kα and Kβ XES experiments were conducted inside a N2 glovebox to prevent unintentional air oxidation. Transmission-mode Ni K-edge XAS was conducted on a benchtop spectrometer.Upon exposure to air, as-synthesized Ni2P nanoparticles were studied via P Kα and Kβ XES. Results showed that the phosphide species converted to phosphate with analysis of intermediates well fit by a simple two-phase mixture. Phosphide:phosphate ratios were quantified using linear combination analysis, providing a powerful tool to analyze P speciation on various samples in an inert environment and with minimal loss of material, both advantages of this system over 31P magic angle spinning solid state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy. Continued work looks at analyzing the effects of the ligand environment on the stability of nanoparticles in electrolytes spanning from acidic to basic pH. We hypothesize that ligands will significantly stabilize the nanoparticles against corrosion and that without ligands Ni2P readily converts to a nickel phosphate species upon exposure to electrolyte.References(1) Popczun, E. J.; McKone, J. R.; Read, C. G.; Biacchi, A. J.; Wiltrout, A. M.; Lewis, N. S.; Schaak, R. E. Nanostructured Nickel Phosphide as an Electrocatalyst for the Hydrogen Evolution Reaction. J. Am. Chem. Soc. 2013, 135 (25), 9267–9270. https://doi.org/10.1021/ja403440e.(2) Liu, P.; Rodriguez, J. A. Catalysts for Hydrogen Evolution from the [NiFe] Hydrogenase to the Ni2P(001) Surface: The Importance of Ensemble Effect. J. Am. Chem. Soc. 2005, 127 (42), 14871–14878. https://doi.org/10.1021/ja0540019.(3) Bullock, M.; More, K. Basic Energy Sciences Roundtable: Foundational Science for Carbon-Neutral Hydrogen Technologies (Report); DOESC Office of Basic Energy Sciences, 2022. https://doi.org/10.2172/1834317.(4) Layan Savithra, G. H.; Muthuswamy, E.; Bowker, R. H.; Carrillo, B. A.; Bussell, M. E.; Brock, S. L. Rational Design of Nickel Phosphide Hydrodesulfurization Catalysts: Controlling Particle Size and Preventing Sintering. Chem. Mater. 2013, 25 (6), 825–833. https://doi.org/10.1021/cm302680j.(5) Rodriguez, J. A.; Kim, J.-Y.; Hanson, J. C.; Sawhill, S. J.; Bussell, M. E. Physical and Chemical Properties of MoP, Ni2P, and MoNiP Hydrodesulfurization Catalysts: Time-Resolved X-Ray Diffraction, Density Functional, and Hydrodesulfurization Activity Studies. J. Phys. Chem. B 2003, 107 (26), 6276–6285. https://doi.org/10.1021/jp022639q.(6) Menezes, P. W.; Indra, A.; Das, C.; Walter, C.; Göbel, C.; Gutkin, V.; Schmeiβer, D.; Driess, M. Uncovering the Nature of Active Species of Nickel Phosphide Catalysts in High-Performance Electrochemical Overall Water Splitting. ACS Catal. 2017, 7 (1), 103–109. https://doi.org/10.1021/acscatal.6b02666.(7) Ha, D.-H.; Han, B.; Risch, M.; Giordano, L.; Yao, K. P. C.; Karayaylali, P.; Shao-Horn, Y. Activity and Stability of Cobalt Phosphides for Hydrogen Evolution upon Water Splitting. Nano Energy 2016, 29, 37–45. https://doi.org/10.1016/j.nanoen.2016.04.034.(8) Parra-Puerto, A.; Ng, K. L.; Fahy, K.; Goode, A. E.; Ryan, M. P.; Kucernak, A. Supported Transition Metal Phosphides: Activity Survey for HER, ORR, OER, and Corrosion Resistance in Acid and Alkaline Electrolytes. ACS Catal. 2019, 11515–11529. https://doi.org/10.1021/acscatal.9b03359.

(Invited) Advances in XPS Analysis of Battery Materials

Energy storage (batteries, capacitors) and conversion (solar cells) systems are increasing demand for vehicles, mobile electronics, and other areas as alternatives to fossil fuels.These systems are complex and multi-component with many materials and interfaces that are difficult to handle and characterize. To optimize materials properties and improve battery lifetimes, there is a pressing need for physicochemical characterization approaches with air-free handling capabilities, high spatial resolution, the ability to analyze buried interfaces without damaging the chemistry, and the need to bridge the gap by in situ and operando surface analysis.Developments in X-ray Photoelectron Spectrometers (XPS) open up new capabilities to address these challenges. In this talk, I will discuss how we can overcome obstacles in analyzing battery materials using: Inert environment transfer vessel: This allows for handling battery materials in an air-free environment, which is essential for preventing oxidation and other degradation reactions.Microprobe X-ray source with <5 µm spatial resolution: This provides high spatial resolution for analyzing small areas of interest, such as SEI, dendrites and other features.Hard X-ray source and cluster ion gun source: These allow for the analysis of buried interfaces not accessible by conventional soft X-ray XPS.In situ energy gap measurements: These allow for the study of the changes in the electronic structure of battery materials as they are cycled, which can provide insights into the mechanisms of charge storage and discharge.Operando XPS experiments: These allow for the study of the changes in the surface structure of battery materials as they are operating, which can provide insights into the factors that affect their performance. Figure 1

Char from Pyrolysis of Waste Tires to Increase Bitumen Performances

Road pavement characteristics can be improved by modifying bitumens through addition of fine particles. To avoid environmental issues, attention is recently being paid to bio-materials. In this study, a 50/70 bitumen was modified through the addition of char obtained from the pyrolysis of waste tires. Char addition causes an increase in transition (gel to sol) temperature of up to 4 °C and an increase in rigidity under working conditions (50 °C) of up to about one order of magnitude. The effect of the gas type flowing under the pyrolysis process (CO2, N2 and CO2 + N2) on the mechanical characteristics of the bitumen was also investigated. More marked effects on the rheological performances were found if char coming from pyrolysis under CO2 was used (the gel-to-sol transition temperature is increased by about 4.5 °C) compared to that coming from pyrolysis under N2 (gel-to-sol transition temperature is increased by about 3 °C). The effect is at a maximum for char from CO2 at 3% wt/wt, whereas regarding char from N, a lesser effect is seen with a more uniform (flat) effect as a function of char% and with an increase in gel-to-sol transition temperature of about 3 °C. Coherently, char obtained from pyrolysis under CO2 was found to possess a higher surface area constituted by smaller particles than that coming from pyrolysis under N2. In fact, the BET-specific surface passes 79 m2/g for N2-char to 174 m2/g for CO2-char and the micropore volume fraction increases from 2 to 9. The observed differences can be attributed to the oxidizing environment (CO2) that is more aggressive and reactive in the synthesis phase compared to an inert environment (N2). Char also showed an anti-aging effect, hindering the increase in rigidity typically associated with the aging process. This effect was explained in terms of the compatibility of char with bitumen’s organic nature, and presumably its more effective hosting in a bituminous structure, which is presumably higher when char is produced under CO2 rather than N2. This study quantitatively indicates how a residue derived from the pyrolysis of a waste material can be efficiently re-used to increase the mechanical characteristics of bitumen, accomplishing the recent circular-based needs for environmental protection.

Ligand Decomposition Differences during Thermal Sintering of Oleylamine-Capped Gold Nanoparticles in Ambient and Inert Environments: Implications for Conductive Inks.

Gold nanoparticles (GNPs) are essential in creating conductive inks vital for advancing printable electronics, sensing technologies, catalysis, and plasmonics. A crucial step in fabricating useful GNP-based devices is understanding the thermal sintering process and particularly the decomposition pathways of ligands in different environments. This study addresses a gap in the existing research by examining the sintering of oleylamine (OA)-capped GNPs in both ambient (air) and inert (N2) environments. Through a series of analyses including TGA/MS, Raman spectroscopy, and XPS, distinctive OA decomposition behaviors were identified in air and nitrogen environments. The research delineates two OA decomposition pathways resulting in different porosity, microstructure, and electrical conductivity of GNP films sintered in air and nitrogen environments. The study offers some insights that can steer the sintering and utilization of the GNP sintering process and promises to aid the future development of nanoparticle-based printable electronics.

Mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene (PTFE)

AbstractCarbon fiber reinforced polytetrafluoroethylene (CF/PTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. Moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/PTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/PTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/PTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. Moreover, a loosely adhered tribofilm was observed on top of the CF/PTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm could be an indication of moisture-driven lubrication by the non-graphitic carbon in the tribofilm.

Temperature‐dependent wear characteristics of ZE41 magnesium alloy under air and inert environments

AbstractDry sliding wear behaviour of ZE41 magnesium alloy was evaluated under the air and argon environment at room temperature, 125 °C, and 250 °C. The coefficient of friction was increased with increasing the test temperature. At room temperature and 125 °C, the friction coefficient was reduced in the argon environment. However, at 250 °C, the friction coefficient in the argon environment was measured as higher compared to that of the tests conducted in the air environment. The wear rate increased with the increasing temperature. However, a lower wear rate was observed in the case of argon atmosphere than in air for all the test temperatures. Abrasion and delamination were dominant wear mechanisms at room temperature and 125 °C, whereas at 250 °C, thermal softening and shearing were found to be dominant. Furthermore, oxidation wear was observed as the prominent mechanism in the air environment.

Peculiarities of high-temperature refining of carbon materials

The purpose of the study was to determine the influence of the main following factors on the efficiency of the process of high-temperature refining of natural and artificial graphite: processing temperature, distribution of metal oxides, and changes in the aggregate state of ash impurities. Thermal processing of natural graphite from Ukrainian deposits and anthracite from Donetsk coal basin was carried out in a chamber furnace at a holding time of 10–20 minutes in a temperature range of 1500–30000С. The quality of refining was carried out by ICP-OES and XRF analysis methods. It was established that the refining process may be divided into three following periods: 0–16000С (removal of moisture, volatiles, and decomposition of carbonates); 1600–26000С (evaporation of main ash-forming metals Fe, Si, Al, Ca, Mg in the form of oxides, silicides, and carbides); and 2600–30000С (evaporation of refractory compounds Ti, V, Mo, the content of which in the initial raw material determines the processing temperature and the quality of the final product). The distribution of metal oxides in the initial carbon material is not uniform, which complicates the use of equilibrium state models. The transition of ash into the liquid and then gaseous state has a significant impact on the result of heat treatment. This is what determines the choice of the process scheme. Intermittent process is the heating by an external heater in an inert gas environment. Continuous process is the heating of the material in moving containers or processing in an electrothermal fluidized bed.