Oxygen Glow Discharge Research Articles

High Porous Activated Carbon Electrode Derived from Watermelon Peel Biomass Exposed with DC Glow Discharge Plasma Applied for Super Capacitors

The growing demand for sustainable and environmentally-friendly technologies has spurred the exploration of innovative methods for waste management and resource utilization. Among the various bio-wastes generated globally, watermelon peel emerges as a significant contributor. To characterize carbon materials in the presence of functional groups, for morphological analysis, and intensity, we subjected activated fruit peel carbon to X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman studies. Furthermore, we examined its electrochemical performance. Another method used to assess wettability is the contact angle. Watermelon-rind-activated carbon was exposed to a DC glow discharge oxygen and air plasma with a 450 V applied potential. The air-treated carbon demonstrated a noteworthy capacitance of 1669 F g−1 at 0.5 mA g−1 in a 2 M KOH electrolyte. Our study found that the properties of the activated carbon were enhanced through cold plasma treatment. This research provides valuable insights into the potential resources of fruit peels and proposes a novel adsorbent with cost-effective advantages in supercapacitors, which could provide effective energy storage for portable gadgets, electric cars, and renewable energy systems, thus presenting a solution for sustainable waste management.

Response of the modified GAFCHROMIC EBT2 radiochromic film to DC glow discharge plasma

The response of the modified GAFCHROMIC EBT2 radiochromic film to DC Oxygen glow discharge plasma was investigated using a flatbed scanner and an UV–Vis spectrophotometer. The film was modified by removing the polyester overlaminate, adhesive, and topcoat layers with a total thickness of 80 µm, and is now referred to as EBT2-M. The EBT2-M films were exposed to DC Oxygen plasma for different durations: 0, 0.5, 1, 2, 3, 4, 7, and 10 min. The exposed films exhibit coloration homogeneity with an average variation of (1.6 ± 0.3) × 10−4 pixel values/µm, irrespective of the applied exposure time. The pixel values of the red-and-green channels and weighted grayscale images decreased exponentially with different sensitivity amounts to ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 39.67, 49.69, and 42.11 min−1, respectively, as the exposure time increased. The two absorption peaks at 580 ± 4 nm and 632 ± 4 nm in the UV–Vis absorption spectra of the exposed GAFCHROMIC EBT2-M radiochromic films are increasing with increasing exposure time up to 4 min, thereafter saturated for prolonged exposure time. The integrated absorbance in the range from 400 to 700 nm is linearly correlated with the exposure time. The indirect and direct optical energy band gaps and Urbach energy of the modified GAFCHROMIC EBT2 film are weakly correlated with the exposure time. These findings suggest the utilization of the modified GAFCHROMIC EBT2 radiochromic film as a novel and simple technique for plasma diagnostics.

Differential Etching of Rays at Wood Surfaces Exposed to an Oxygen Glow Discharge Plasma.

Basswood samples were exposed to oxygen glow-discharge plasmas for 30 min, and etching of radial and tangential longitudinal surfaces was measured. It was hypothesized that there would be a positive correlation between etching and plasma energy, and differential etching of wood surfaces because of variation in the microstructure and chemical composition of different woody tissues. Etching at the surface of basswood samples was examined using profilometry. Light and scanning electron microscopy were used to examine the microstructure of samples exposed to plasma. There was a large effect of plasma energy on etching of basswood surfaces, and radial surfaces were etched to a greater extent than tangential surfaces. However, rays at radial surfaces were more resistant to etching than fibers, resulting in greater variation in the etching of radial versus tangential surfaces. The same phenomenon occurred at radial surfaces of balsa wood, jelutong and New Zealand white pine subjected to plasma etching. The possible reasons for the greater resistance of rays to plasma etching are explored, and it is suggested that such differential etching of wood surfaces may impose a limitation on the use of plasma to precisely etch functional patterns at wood surfaces (raised pillars, grooves), as has been done with other materials.

Plasma-induced reversible surface modification and its impact on oxygen heterogeneous recombination

A novel model is developed for atomic oxygen surface kinetics in silica-like walls, introducing a plasma-induced surface modification, which may impact intermediate pressure plasma reactors. The model is the first to reproduce experimental measurements in an oxygen glow discharge operating in the pressure range between 0.27 mbar (0.2 Torr) and 4 mbar (3 Torr), showing a decrease with pressure of the O recombination probability on Pyrex between 0.27 mbar and 1 mbar. The numerical simulations suggest that a modification is induced by the production and destruction of metastable chemisorption sites at the surface. As such, the Langmuir–Hinshelwood (L-H) and Eley-Rideal (E-R) recombination mechanisms take place involving not only physisorption and stable chemisorption sites, but also metastable chemisorption sites, produced by the impact of fast O2 ions and neutrals. The presence of metastable sites can be reversed by increasing the plasma pressure.

Chemical and morphological modification of softwood and hardwood surfaces by an oxygen glow discharge plasma

High-energy radiation preferentially degrades cellulose and enriches lignin content at wood surfaces particularly in hardwoods. Accordingly, we hypothesize that a similar effect will occur at surfaces exposed to plasma. We test this hypothesis by plasma-treating pine and poplar veneers and assessing changes in the lignin and holocellulose-derived sugar-content of veneers; quantifying etching of pellets containing lignin and cellulose, and observing etching of different cell wall layers in pine and Homalium. The majority but not all of our results support our hypothesis. Lignin-rich regions of wood cell walls were easier to see after plasma treatment. We discuss the potential uses of plasma-etching for the study of wood ultrastructure and the creation of wood surfaces with self-bonding properties, and conclude that plasma-etching can be used as an alternative to chemical pretreatments for ultrastructural studies of the distribution of lignin in wood cell walls.

Mechanical failure characterization of oxygen plasma modified UHMWPE/vinyl ester composites using acoustic emission

This study reveals the mechanical and interfacial bonding properties of glow discharge oxygen plasma modified ultrahigh molecular weight polyethylene (UHMWPE)/vinyl ester composites modified by oxygen plasma. The composites’ flexural, tensile, and impact-resistant properties were estimated, and the failure mechanism was analyzed by acoustic emission (AE) testing. The flexural stress, tensile stress, and impact-resistance force of the modified three plain weave structures composites are 193.37–734%, 11–15%, and 16–17% higher than those without modification. It depends on flexibility, interfacial bonding strength, reinforcement structure, and stiffness. In addition to the flexural properties, the tensile and impact properties increase with fiber volume fraction. In the AE test, the flexural and tensile cumulative energies without modification are 9230.42 mV*mS and 1.735 V*S higher than modified materials. The characteristic frequency range of each failure mechanism is determined by cluster analysis. Low, medium, and high frequency correspond to matrix cracking, fiber/matrix debonding, and fiber breakage. Oxygen plasma contributes to the wettability of the reinforcement and the interfacial bonding strength, resisting cracking growth.

Анализ вольт-фарадных характеристик МДП-структур с ALD Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- на n- и p-CdHgTe, стабилизированном сверхтонким собственным оксидом

Capacitance−voltage characteristics of metal dielectric semiconductor structures with atomic layer deposition Al2O3 on n- and p-Cd0.22Hg0.78Te (with and without a surface graded-gap layer) preliminary oxidized in oxygen glow discharge plasma (with the resulting oxide thickness of 2 nm) have been studied. The obtained structures reveal the positive fixed charge with a density of ∼ (1−6) · 10^11 cm^(−2). The ratio between a slow surface states density and a surface band gap width is almost independent on graded-gap layer presence, with the value of ∼ (4−8) · 10^11 cm^(−2) · eV^(−1). The proposed passivation approach provides near-ideal low-frequency capacitance-voltages characterized by weak influence of fast surface states. Films of CdHgTe grown without the graded-gap surface layer are proved to be much more sensitive to the process of oxidation in glow discharge plasma.

Studying C-V characteristics of MIS structures with ALD Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- on n- and p-CdHgTe stabilized with ultra-thin native oxide

Capacitance--voltage characteristics of metal dielectric semiconductor structures with atomic layer deposition Al2O3 on n- and p-Cd0.22Hg0.78Te (with and without a surface graded-gap layer) preliminary oxidized in oxygen glow discharge plasma (with the resulting oxide thickness of 2 nm) have been studied. The obtained structures reveal the positive fixed charge with a density of ~(1-6)·1011 cm-2. The ratio between a slow surface states density and a surface band gap width is almost independent on graded-gap layer presence, with the value of ~(4-8)·1011 cm-2·eV-1. The proposed passivation approach provides near-ideal low-frequency capacitance-voltages characterized by weak influence of fast surface states. Films of CdHgTe grown without the graded-gap surface layer are proved to be much more sensitive to the process of oxidation in glow discharge plasma. Keywords: mercury cadmium telluride, film, surface states, plasma.

Enhancements of the Mechanical Properties for Banana/Sisal Fibers by Cold Glow Discharge Oxygen Plasma Treatment

Enhancements of the Mechanical Properties for Banana/Sisal Fibers by Cold Glow Discharge Oxygen Plasma Treatment

A single step approach of fabricating superhydrophobic PET fabric by using low pressure plasma for oil-water separation

Superhydrophobic surfaces play a significant role in functional materials which are the most important part of surface and interface science. Superhydrophobic materials for oil/water separation have become a worldwide research topic due to the industrial waste and oil leak causing environmental pollution. A single step, solvent free method to fabricate superhydrophobic surface seems to be challenging. The current study focuses on a new and advancement methodology to fabricate fluorine and silane free smart oil-recovery materials without adverse environmental consequences. A superhydrophobic PET fabric is fabricated by DC glow discharge oxygen plasma treatment which is a simple and quick method. The incorporation of functional groups to the PET fabric promoted the superhydrophobic nature of the fabric with the water contact angle of 163°. The as prepared fabric possess excellent repellency to water, milk, coffee and can be applied as an effective material for oil/water separation, protective garments, diaper pads and other medical and health supplies.

Mechanism of High-Efficiency Electron Beam Generation in a High-Voltage Discharge in Helium and Its Mixtures with Oxygen and Nitrogen

The results of investigation of the current-voltage characteristics (CVCs) and electron beam generation efficiency in continuous discharges in helium, its mixtures with oxygen and nitrogen, as well as in pure oxygen and helium are presented. Peculiarities of CVCs are singled out and interpreted in terms of a changed role of the principal emission mechanisms with an increase in the voltage. It is shown that a high efficiency of the electron beam generation of more than 80% can be achieved in glow discharges in helium, oxygen, and nitrogen. In helium, it is provided by the predominating photoemission, while in oxygen and nitrogen and their mixtures with helium – mainly by the kinetic emission under the impact of fast heavy particles.

Численный расчет электрофизических и термодинамических характеристик плазмы тлеющего разряда в кислороде атмосферного давления, формируемой после искрового пробоя

Численный расчет электрофизических и термодинамических характеристик плазмы тлеющего разряда в кислороде атмосферного давления, формируемой после искрового пробоя

Optimization of plasma process parameters for surface modification of bamboo spunlace nonwoven fabric using glow discharge oxygen plasma

In this study, Box–Behnken design was used to study the effect of optimization of plasma treatment on surface modification of bamboo spunlace nonwoven fabric. The effect and interaction of the process variables of glow discharge oxygen plasma treatment, i.e. discharge power, exposure duration and inter-electrode spacing on fabric characteristics such as mass per unit area, thickness, breaking force and elongation, air permeability, water vapour permeability and wicking were analysed. The optimum conditions of discharge power 650 W, exposure duration 55 s, and inter-electrode spacing 4 cm were arrived using response optimizer tool of Minitab software. The fabrics showed better characteristics in terms of air permeability, water vapour permeability, wicking and elongation and showed slight reduction in terms of fabric weight, thickness and breaking force. Fourier-transform infrared spectroscopy spectra analysis confirmed the increased functionality of the material after plasma treatment.

Kinetic Features of Modification of Polycarbonate in Oxygen Plasma

Changes in the composition of the surface layer of Lexan 8010 polycarbonate after treatment in plasma of the positive column of oxygen glow discharge have been investigated. The effect of the amount of the processed polymer on the etching kinetics and surface modification of polycarbonate has been shown. It has been established that an increase in the amount of the polymer processed in plasma leads to a change in the gas phase composition, the concentrations of active species, and their fluxes onto the sample, and, as a consequence, a change in the composition of the modified surface layer of polycarbonate.

Flow Reactor Experimental Study of H2/O2 and H2/Air Mixtures Ignition Assisted by the Electrical Discharge

ABSTRACTThe paper presents the results of experimental study of the influence of a glow discharge in oxygen on the ignition of hydrogen/oxygen and hydrogen/air mixtures in the low-pressure flow reactor at temperature range 800–1070 K. The study focuses on obtaining the data on the effect of electronically excited molecules O2(a1Δg) on the ignition delay in presence of the minor amount of other discharge products. In order to reduce the effect of O atoms and O3 molecules, the walls of the discharge cell and output duct were coated with mercury oxide. The special attention was paid to the diagnostics of discharge products and the evaluation of the influence of reactor walls on the heterogeneous deactivation of O2(a1Δg) molecules along the reactor. The spectroscopic technique was used for the measurements of O2(a1Δg) and O3 concentrations. It was shown that the induction zone length in H2-O2 and H2-air mixtures could be reduced by 10–50% depending on the initial temperature in the case of glow discharge exposure on the oxygen flow.

Neon plasma for effective ionisation of oxygen and fluorine in pulsed glow discharge – high ionisation energy elements' quantification in potassium titanyl phosphate single crystals

Neon plasma significantly benefited the determination of high ionisation energy elements in dielectric crystals by pulsed GD MS.

Fluid model of H‐form of the positive column in DC oxygen glow discharge

In our contribution, the positive column of oxygen DC glow discharge is investigated using methods of computational physics at medium pressures (200–687 Pa) and discharge currents from 20 to 40 mA. Under mentioned conditions, the attributes of the DC oxygen discharge are particular, what is based on the existence of two forms: H‐form and T‐form. One‐dimensional fluid model of the stable H‐form has been developed. Not only radial profiles of various species in cylindrical tube but also the reaction among them and their interaction with the walls are taken into account. The model is built on the continuous description of concentration of species and drift‐diffusion approximation of the particle flux. The results of the simulation are in good agreement with experimental ones.

Carbon dioxide reforming of methane on a cobalt catalyst subjected to plasma–chemical treatment

The effect plasma–chemical treatments of 5 wt % Со/SiO2 catalyst have on its activity in the carbonic acid conversion of methane in the interval of 700 to 900°C is studied. A plasma glow discharge in oxygen and argon was used along with high-frequency plasma in hydrogen for preliminary treatment of the catalyst. A multiple increase in СН4 and СО2 conversion and a 30–50 K drop in the temperature of the onset of the reaction are observed after plasma–chemical treatments. The strongest increase in activity is measured after the catalyst is treated with oxygen plasma. X-ray photoelectron spectroscopy is used to determine the change in the composition of the catalyst’s surface after it is treated with plasma, indicating that active forms of carbon atoms can be included in new active centers.

Influence of the surface morphology of aluminum foil on the probability of heterogeneous recombination of О(3Р) atoms in oxygen plasma

The process of recombining oxygen atoms on the surface of an aluminum foil and thin film is investigated in the positive column of the DC glow discharge in oxygen at a gas pressure of 200 Pa, a discharge current of 50 mA, and surface temperatures of 350–530 K. It is shown that an increase in the average surface roughness leads to a decrease of the probability of the heterogeneous recombination of O(3P) atoms. The values of the apparent activation energy for the process of heterogenic recombination of oxygen atoms are calculated.

Kinetic features of plasma etching of polycarbonate in oxygen plasma

Changes in surface properties and composition of the surface layer of polycarbonate of the Lexan LS2 and Lexan 8010 brands after treatment in the positive column of glow-discharge oxygen plasma have been studied. The amount of the polymer loaded for processing has been shown to affect the kinetics of etching and modifying the polycarbonate surface. It has been found that an increase in the amount of the polymer in the plasma reduces its etching rate and also affects the electrical parameters of plasma, which in turn can cause a change in the flux of active species onto the polymer surface and, consequently, a change in the rate of plasma-initiated heterogeneous processes.