Radio Frequency Plasma Treatment Research Articles

Enhanced performance of polydimethylsiloxane-based triboelectric nanogenerator using BaTiO3/MWCNTs

Triboelectric nanogenerators (TENGs) that operate in the contact-separation mode are widely utilized for energy harvesting owing to their simple structure, excellent durability, and high energy-conversion efficiency. This study investigated the enhanced performance of TENGs using polydimethylsiloxane (PDMS) incorporating barium titanate (BTO) and multiwalled carbon nanotubes (MWCNTs). The negative triboelectric layer, comprising PDMS with BTO and MWCNTs, and aluminum foil as both the positive triboelectric layer and electrode, were optimized to improve the TENG performance. The optimal composition of PDMS incorporating 0.01 wt% MWCNTs and 10 wt% BTO yielded output voltage and current of 394.75 V and 28.24 µA, respectively. Further enhancement was realized via the application of radio frequency plasma treatment, which increased the surface roughness and fluorine incorporation. Consequently, the output voltage and current improved to 421.06 V and 32.33 µA, respectively, with a peak power density of 4.76 W/m2 at 10 MΩ. The optimized TENG maintained consistent performance over 2000 cycles and successfully illuminated commercial LEDs, thereby demonstrating its potential for practical energy-harvesting applications.

Ar/NH3 Radio‐Frequency Plasma Etching and N‐doping to Stabilize Metallic Phase 1T‐MoS2 for Fast and Durable Sodium‐Ion Storage

AbstractMetallic phase 1T‐MoS2 is considered a prospective anode material for sodium‐ion batteries (SIBs) due to its remarkable electrical conductivity and unique layered structure. However, 1T‐MoS2 is thermodynamically unstable and prone to phase transition to the 2H‐MoS2 phase. Herein, self‐supporting nitrogen‐doped and carbon‐coated 1T/2H mixed‐phase MoS2 nanosheets with rich sulfur vacancies on carbon cloth (C@N‐MoS2‐p/CC) are synthesized through a hydrothermal method and Ar/NH3 radio‐frequency (RF) plasma treatment process. Density‐functional‐theory (DFT) calculations demonstrate that after Ar/NH3 RF plasma treatment, nitrogen‐doping and etching effects are realized, which combine with carbon‐coating significantly reduce the phase transition energy of 1T‐MoS2, thus triggering the phase transition and enabling the stable existence of the highly active 1T‐MoS2. As a result, the C@N‐MoS2‐p/CC exhibits outstanding sodium storage performance, with initial charge–discharge capacities of 701.0/797.0 mAh g−1 at 1 A g−1, respectively. It also demonstrates exceptional rate capabilities and ultra‐high cyclic stability, maintaining a discharge capacity of 404.2 mAh g−1 after 910 cycles at a high rate of 2 A g−1. In a full cell with Na3V2(PO4)3/CC cathode, it exhibits excellent initial charge–discharge capacities of 102.3/102.9 mAh g−1 and maintains satisfactory cycling stability after 350 cycles (86.7 mAh g−1) at 0.1 C.

Development of surface‐treated poly(lactic acid)/zinc oxide biocomposites for 3D printing in bone tissue engineering

AbstractThe increase in bone fractures has been driving the development of materials for bone repair with better mechanical and biological properties. This work reports the development of poly (lactic acid) (PLA)‐zinc oxide (ZnO) biocomposites for 3D printing of scaffolds to be applied in bone tissue engineering. The ZnO surface was functionalized with maleic anhydride (ZnOMA) by applying radio frequency plasma treatment as an alternative to control the catalytic effects of ZnO on the degradation of the PLA during the molten state processing. PLA and ZnOMA powders were processed using a heated internal mixer and the resulted biocomposites were used to manufacture scaffolds by 3D printing. The scaffolds were characterized by their rheological, thermal, microstructural, mechanical, and biological properties. Compositions containing ZnOMA presented higher viscosities, evidencing the control of degradation by surface functionalization, and achieved an elastic modulus near 1 GPa, suitable for bone applications, unlike the untreated samples. In relation to cell functions, PLA‐ZnOMA scaffolds exhibited cell viabilities at 160%, compared to 50% for untreated samples and stimulated mesenchymal stem cells toward osteoblast. Therefore, ZnO's negative thermal degradation effect on PLA was successfully overcome using plasma functionalization, enabling the 3D printing of bioactive scaffolds with great potential for application in tissue engineering.

A game-changing equation during the etching of tuning forks and its verification through experiments

Quartz tuning fork (QTF) sensors, characterized by simplicity, low cost, and high-quality factor, represent a significant subset. This study delves into the etching dynamics of QTF systems, crucial for sensor applications like quartz crystal microbalance (QCM). Both theoretical and experimental investigations into QTF etching, via methods like electro-etching for large-scale tuning forks (TF) and low-pressure radio frequency (RF) plasma treatment for QTFs, have been conducted. Surprisingly, post-etching measurements reveal a lower vibrational frequency for both large-scale TFs and QTFs compared to their bare counterparts, unlike QCM sensors. A novel formula correlating this frequency reduction to mass loss has been proposed and validated through lots of experiments. Notably, longitudinal homogeneity emerges as a pivotal factor influencing the accuracy of the proposed formula. In summary, the novel mathematical framework presented herein is poised to catalyze the widespread adoption of low-cost QTFs as mass-sensitive biosensors, marking a significant advancement in the field.

Collagen‐cellulose‐poly(l‐lactide) scaffold by electrospinning and plasma‐assisting fabrication for bone tissue engineering applications

AbstractNovel biomaterials suitable for bone tissue engineering are currently in demand, and reformulating natural and synthetic biomaterials has caught scientists' attention. Cellulose and collagen have been utilized in biomedical fields. This research aimed to fabricate collagen‐cellulose‐poly(l‐lactide) (Col‐Cel‐PLL) scaffold using collagen, cellulose, and poly( l‐lactide) through electrospinning and radiofrequency plasma treatment and to examine the scaffold's physicochemical and biological properties. Fourier transform infrared spectroscopy revealed its chemistry, and scanning electron microscopy showed fine interconnecting microfibrous fibers; it was super‐hydrophilic with low crystallinity (25.59%) and great Young's modulus (163.940 ± 8.008 MPa), and it was reasonably degraded. Regarding biological properties, the scaffold was biocompatible by supporting cell attachment and viability. Cells on the Col‐Cel‐PLL produced high total protein levels and collagen deposition. However, the alkaline phosphatase activity was significantly low.

Improvement of water and gas barrier properties of polycarbonate by the SiOx plasma treatment

The purpose of this research paper was to improve the water and gas barrier properties of polycarbonate (PC) by the deposition of organosilicon thin films through radio-frequency plasma treatment. For optimization, different treatment parameters (namely, the discharge power, the deposition time, and the ratio q between O2 and hexamethyldisiloxane) were varied. The influence of the plasma coating of low thickness (30–308 nm) on the surface and structure properties of PC and on its thermal stability was analyzed. The resistance toward gases (N2, O2, CO2) and water was investigated through permeation measurements. The results have shown that increasing the ratio q from 5 to 12.5 allows obtaining a layer of more inorganic nature and a O/Si ratio close to 2 enhances the PC thermal stability. It has been found that the barrier properties of the treated PC film mainly depend on the morphology of the deposited coating, its homogeneity and the surface wettability. For instance, with q = 7.5 leading to the less hydrophilic and more homogeneous treated surface, the barrier effect significantly increased, as the obtained barrier improvement factor was ∼ 60 % for gases and 24 % for water.

Nitrogen Radiofrequency Plasma Treatment of Graphene

AbstractThe incorporation of nitrogen (N) atoms into a graphitic network such as graphene (Gr) remains a major challenge. However, even if the insertion mechanisms are not yet fully understood, it is certain that the modification of the electrical properties of Gr is possible according to the configuration adopted. Several simulations work, notably using DFT, have shown that the incorporation of N in Gr can induce an increase in the electrical conductivity and N acts as an electron donor; this increase is linked to the amount of N, the sp2/sp3 carbon configuration, and the nature of C−N bonding. Nitrogen radiofrequency (RF) plasma has been used to incorporate N into Gr materials. The RF plasma method shows the possibility to incorporate N‐graphitic nitrogen into Gr after a pre‐treatment with nitric acid. X‐ray photoelectron spectroscopy and Raman spectrometry were used to quantify the functionalized groups. The modifications of the graphene surface chemistry along the amount of N inside the Gr change the chemical environment of N. This method, enabling the incorporation of N inside Gr matrix, opens up a route to a broad range of applications.

Deep understanding the formation of hollow ZnO@ZnS core-sheath heterojunction towards efficient CO2 photoreduction

The utilization of solar energy to convert CO2 into small energy molecules is a potential “carbon neutral” technology for CO2 emission reduction. However, the industrial application is significantly constrained due to the low reduction efficiency, complexity of the synthesis methods, and limitations in scaling up the catalyst materials. In this work, we have successfully designed and synthesized a series of hollow tubular ZnO@ZnS core-sheath heterostructured materials, by combining radio-frequency thermal plasma and hydrothermal treatment technologies. The S:Zn molar ratio, reaction time, and temperature were systematically investigated, and the morphology of intermediate products was successfully captured, which provided conclusive evidence for the proposed formation mechanism. Notably, the photocatalytic CO yield of the ZS0.5O hollow nanotube core-sheath composite is not only 3.20 or 4.03 times higher than that of the pure ZnO or ZnS, respectively, but also possesses excellent stability. By in-depth characterization, we found that the hollow core-sheath heterostructure enhances light capture and absorption, exposes more effective active sites, and builds a type-II heterojunction between ZnO and ZnS to enhance the separation efficiency of charge carriers. The synergy of these factors significantly improves the catalytic performance, offering new insights for photocatalytic, electrocatalytic, and photoelectrocatalytic CO2 reduction.

Advanced high-iron coal fly ash zeolites for low-carbon emission catalytic combustion of VOCs

Coal fly ash zeolites (CFAZs) with increased iron oxide content were prepared by double-stage alkaline conversion of high-iron lignite coal ash. Catalysts were modified by applying radiofrequency plasma treatment with trifluoromethane (RF CHF3) to increase their surface activity. Textural, compositional, and structural characterization of the parent and plasma-modified zeolites were performed by N2-physisorption, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FT-IR) spectroscopy. Oxidation state and coordination of iron species were studied by Mössbauer spectroscopy, UV-Vis spectroscopy and temperature-programmed reduction method (TPR). Acidic properties were investigated by FT-IR spectroscopy of adsorbed pyridine. The initial and plasma-modified samples were studied under toluene oxidation, where toluene was used as a model VOC. The plasma-modified iron-enriched zeolite was found to exhibit high catalytic activity for VOC oxidation, reaching a 98% toluene conversion rate at 500 °C. Despite some structural degradation effects, the plasma-treated catalysts outperformed the untreated ones in catalytic activity. Furthermore, CO2 adsorption capacity of the plasma-modified zeolite was investigated under dynamic conditions. Although plasma-treated iron-enriched zeolite showed relatively low specific surface area (194 m2/g), high dynamic carbon capture capacity of 3.8 mmol/g was measured. It significantly exceeded the capacity of CFAZs with higher specific surface area, not to mention the pure zeolite phase.

N-plasma modulation for boosting electromagnetic wave absorption behavior of MoO3 ceramic based on non-metallic doping

Rational design and fabrication of MoO3 ceramic with controllable electronic structure is expected to deliver favorable magnetic moments, leading to excellent electromagnetic behavior. However, achieving large-scale precise modulation of the MoO3 electronic structure is still a challenge. Here, a low-temperature, high-efficiency nitrogen radio frequency (RF) plasma treatment method was adopted to modify the surface of MoO3 with N doping and investigate its electromagnetic wave absorption (EMA) mechanism in depth. After MoO3 powder treating with N2 plasma for 30 s, at the doping ratio is 70%, the minimum reflection loss (RLmin) is –43.35 dB and the maximum effective absorption bandwidth (EAB) could reach 6.16 GHz at a low thickness (2.1 mm). The significant improvements in dielectric loss and permeability loss of N-doped MoO3 are because the doping of N atoms reduces the bandgap of MoO3, promotes electron jumping, dramatically improves electrical conductivity of semiconductors, and introduces interfacial polarization and dipole polarization effects. The presence of magnetic moments renders the N-doped MoO3 with weak magnetic properties and significant eddy current losses. This study provides an explicit EMA mechanism for non-metal doped transition metal oxidation.

Arc-integration of graphite-coated plasmonic satellite-magnetic core nanoassembly: Efficient tailoring of nanostructure/functionality for catalysis of pollutants

Most magnetoplasmonic nanoassemblies with tunable geometries are commonly fabricated by the wet assembly approach, which is greatly restricted by the high complexity and severe conditions. This study applied a facile one-step arc discharge to fabricate graphite-encapsulated magnetic core-gold satellite (FeAu@G) nanoassembly with tailorable morphologies (35.5–58.8 nm of magnetic cores with 4.91- 0.335 nm of shells, and 4.63–9.01 nm of Au satellites with 1–4 graphite layers of shells) and tunable surface functionalization (hydrophobization, amination). The specific formation processes of graphite shells (i.e., dissolution-reprecipitation-graphitization for shells over magnetic cores, deposition-graphitization for shells over Au satellites) is essential to generate this unique nanoassembly. An storage-dependent consuming time for the removal of Cr(VI) by aminated FeAu@G presented an excellent negative linearity with [Au wt.%]/[Au satellite diameter]3. The reusability of aminated FeAu@G could be significantly aroused by the radio-frequency plasma treatment with an enhancement of 198–894 %. Hydrophobic FeAu@G could converse nitroaromatics recycled with an excellent negative linearity of catalytic activity values to the diameter of Au satellites. This work unlocks a versatile platform to design and produce magnetoplasmonic nanoassemblies with ideal complex nanostructures and surface functionality.

Nitrogen implantation into graphene oxide and reduced graphene oxides using radio frequency plasma treatment in microscale

Solvent-free radiofrequency (RF) nitrogen plasma treatment was applied to incorporate nitrogen atoms in relatively high concentration. Graphene oxide (GO) and two reduced GOs of different O-content were used as target substrates to reveal the influence of the functional groups decorating the graphene lattice on the quantity and quality of nitrogen incorporation. Despite the relatively high oxygen content of the samples no N–O bonds develop but three kinds of different N–C bonds of very similar concentration are formed. Reduction of the GO removed the O-groups but did not heal the vacancies where N doping may occur. After two days the implanted N content drops, the N1 state (sp 2 N in pyridine ring, C–N–C) showing the least stability.

Durable and recoverable hydrophilicity of polyethylene terephthalate fabric prepared with plasma selective etching

Durable delustered PET (PET-TiO2) fabric super hydrophilic surface has been obtained by plasma selecting etching. The aging effect of their hydrophilicity after plasma treatment has been investigated with storage time. After Ar/O2 radio frequency (RF) plasma treatment for only 1 min, PET-TiO2 fabric showed water contact angle of 0o. After 10 month storage time, it keeps its water contact angle below 75.7o. Further more, with Xenon light irradiation for 10 min, it is firstly found that it has well-recovered water contact angle to 5°. While the contact angle of PET fabric for 7 min returns to 123.0° and its hydrophilicity disappeared almost completely and showed no response to Xenon light irradiation. The water absorption rate of 7 min plasma treated PET-TiO2 fabric increased by 57.54%. By field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction analysis(XRD) measurement, waviness structure of humps and ridges with irregular particles or pits were found on the plasma treated PET-TiO2 fabric surface and increased Ti atomic percentage was observed. It is verified that TiO2 particles inside PET-TiO2 fiber have been exposed to its surface by plasma selective etching of its organic component. It suppresses the aging effect and is characterized with durable and recoverable hydrophilicity. This one step, quick, green, and cost-reasonable manufacture method has a practical application for durable superhydrophilic surfaces.

Biocompatible enhancement of poly(ethylene terephthalate) (PET) waste films by cold plasma aminolysis

AbstractBACKGROUNDPoly(ethylene terephthalate) (PET) waste films were treated by cold plasma aminolysis to graft primary amino groups (‐NH2) and the surface biocompatibility of the polymer was improved. Aminated PET waste films were obtained by applying radiofrequency (RF) plasma treatment of either diethylenetriamine (DTA) or ethylenediamine (EDA). Aminolysis was applied during 5, 10 and 15 min at plasma power levels of 150, 175 and 200 W.RESULTSWater contact angle study revealed that the surface of PET waste films became more hydrophilic after plasma treatment, the contact angles decreased as exposure time or plasma power increased. Also, X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) detected signals related to ‐NH2 functional groups at the surface of treated PET films. In relation to the biocompatibility properties of the aminated PET waste films, most of them, do not present hemolytic problems, but those treated with DTA at 150 W for 10 min (PET‐DTA/150 W‐10 min) showed the least hemolytic effect. On the other hand, it was proved that plasma treatment of PET waste films conferred a sterilization effect against Pseudomonas aeruginosa bacteria.CONCLUSIONSThe biocompatible properties of PET were improved while the material was sterilized due to the ultraviolet radiation and free electrons generated during plasma treatment. These results suggest that aminated PET waste films have the potential to be used in biological or biomedical applications by taking advantage of ecofriendly technology such as cold plasma and the reuse of waste polymers such as PET from purified water bottles. © 2022 Society of Chemical Industry (SCI).

Structural characterization and enzymatic hydrolysis of radio frequency cold plasma treated starches.

The effect of carbon dioxide-argon radio frequency cold plasma treatment on the in vitro digestion and structural characteristics of granular and non-granular waxy maize, potato, and rice starches was investigated in this study. The effect on the fine structure of waxy potato was very minimal after plasma treatment irrespective of their granular or non-granular form. The short chain length (SCL) of waxy maize and rice (granular and non-granular) starches was reduced leading to subsequent increases in the long chain length (LCL). In vitro digestibility studies showed that cold plasma treatment enhanced (p<0.05) the amount of slowly digestible starches (5.62%; 10.24%) and resistant starches (0.28%; 85.66%) in non-granular waxy maize (WMS NG) and granular waxy potato starches (WPS G), respectively. The amount of rapidly digestible starches increased in granular waxy maize starch (WMS G) (85.08%) but was unaffected in non-granular waxy rice (WRS NG), WPS G, and non-granular waxy potato starches after plasma treatment. FTIR-ATR data confirmed the ability of cold plasma to induce cross-linking in waxy starches specifically in WMS NG, WRS G, WRS NG, and WPS G. Overall, the unit and internal chain structure of the waxy starches were mostly unaffected by radio frequency plasma treatment. Cross-linking served as the dominant mechanism by which plasma altered the structure and digestibility of these starches. PRACTICAL APPLICATION: Cold plasma technology has been suggested as a green technique for starch modification. More research is, however, needed to facilitate the industrial scale up of this technology. In this study, we utilized a carbon dioxide-argon radio frequency cold plasma to modify waxy maize, rice and potato starches. Cold plasma treatment resulted in starches that were resistant to digestion and were highly cross-linked. The cross-linking would give the starches the ability to possibly withstand the high temperatures and shear that can be applied during industrial processing.

Nitrogen Implantation into Graphene Oxide and Reduced Graphene Oxides Using Radio Frequency Plasma Treatment in Microscale

Nitrogen Implantation into Graphene Oxide and Reduced Graphene Oxides Using Radio Frequency Plasma Treatment in Microscale

Impact of corona and radio-frequency plasma treatment on the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)

Impact of corona and radio-frequency plasma treatment on the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)

Plasma methods for preparation of the substrate and fixing the nanoparticles in the obtaining of disposable antibacterial synthetic materials

The presented work is devoted to the study of the use of a gas-discharge plasma of a low-pressure radio-frequency discharge in the processes of preparing substrates and fixing silver nanoparticles in the preparation of antibacterial synthetic non-woven materials for disposable use. The results of the study of antibacterial activity to assess the inhibition of colony formation of E. coli culture on polypropylene non-woven materials for disposable surgical, medical clothing and underwear, as well as personal protective equipment are presented. To assess the antibacterial activity, fluorescent staining of the samples was carried out. The study of the surface of the samples was carried out using a scanning electron microscope. The materials were treated with preparations based on silver nanoparticles; to ensure the uniformity of properties and fixation of the preparations, treatment in radio-frequency gas-discharge plasma was used. The use of radio-frequency gas-discharge plasma treatment in the processes of modification of polypropylene fibers with antibacterial preparations based on silver nanoparticles makes it possible to obtain antibacterial materials with bacteriostatic and/or antibacterial activity over their entire surface area.

Radio-frequency (RF) room temperature plasma treatment of sweet basil seeds (Ocimum basilicum L.) for germination potential enhancement by immaculation

Ocimum basilicum L. is an antiviral and immunity boosting medicinal plant and culinary herb. Potential use of sweet basils in COVID 19 prevention and management is making its demand rise. This study is aimed at germination potential enhancement of sweet basil seeds. Reported study is evidenced with scientific data of radio-frequency cold plasma treatment using Ar + O2 feed gas. O. basilicum seeds, placed inside the rotating glass bottle, were directly exposed to RF (13.56 MHz) plasma produced in Ar + O2 feed gas. Seed treatment was done using RF source power (60 W, 150 W, 240 W), process pressure (0.2 mbar, 0.4 mbar, 0.6 mbar), and treatment time (5 min, 10 min, 15 min) at different combinations. Results show that, the most efficient treatment provide up to ∼89 % of the germination percentage which is an enhancement by 32.3 % from the control. SEM images revealed slight shrinkage in the seed size with eroded appearance over the seed. Enhancement of lipid peroxidation, show that oxidation of seed coat may propagate internally. Water imbibition analysis, of the treated seeds, was carried out for 2−12 hours. Further analysis of seed weight, on every one hour, after soaking shows enhanced water absorption capability except the treatment at 240 W, 0.6 mbar and 15 min. Plasma treatment enhanced carbohydrate content and protein content which is reported to be due to increased primary metabolism. Whereas, increased activity of secondary metabolism results in the enhancement of enzymatic (catalase) and non-enzymatic antioxidants (proline). Vital growth parameters, such as SVI I and SVI II, got amplified by 37 % and 133 % respectively after treatment. Ameliorative effects of plasma treatment are found highly significant with a positive and significant correlation value (p < 0.01) between germination percentages, SVI I, SVI II, carbohydrate, protein and proline show their interrelationship. Ar + O2 plasma treatment is found to bring forth significant changes in the O. basilicum seeds which eventually enhanced the germination potential and it could be a very promising technology for the medicinal crop.

Improving the Physical and Mechanical Performance of Laminated Wooden Structures by Low-Temperature Plasma Treatment

This paper considers the effect of RF plasma on wood in improving the adhesion of binders to wood by increasing its surface wettability. Our study reveals that radiofrequency (RF) plasma treatment causes a greater than threefold decrease in the marginal wetting angle of wood. The greatest effect is achieved in RF plasma treatment in argon, which is on average 5% greater than that of RF plasma treatment in air or in propane/nitrogen mixture. In addition, the power of the RF plasma torch has the greatest influence, and the main influence comes from the voltage applied to the RF plasma torch; current does not have such a significant effect. To achieve a significant effect, the duration of exposure should be at least 5 min, with a total power of 4.05 kW. Studies have been conducted to determine the adhesive strength of wood. An increase in the strength of laminated beams made from RF-treated bars in relation to control samples was found. The greatest impact on the adhesion strength was revealed when using PVA-based glue, compared with the use of polyurethane-based adhesives and urea-formaldehyde resin.