Low-temperature Nitrogen Plasma Research Articles

Cold Nitrogen Plasma: A Groundbreaking Eco-Friendly Technique for the Surface Modification of Activated Carbon Aimed at Elevating Its Carbon Dioxide Adsorption Capacity

The commercially available activated carbon was modified using barrier and spark discharge low-temperature nitrogen plasma treatment. The samples were investigated using nitrogen sorption at a temperature of −196 °C, XRD, SEM, and FTIR methods, and elemental analysis. The nitrogen content on the surface was increased, but other properties, such as specific surface area, total pore volume, pseudocrystallite height, and pseudocrystallite width, remained unchanged. The activated carbons after nitrogen plasma treatment indicated higher CO2 adsorption than the pristine ones. Since the investigated materials only differed in their nitrogen content, it has been unequivocally demonstrated that the increased presence of nitrogen is responsible for the enhanced adsorption of CO2. The low-temperature nitrogen plasma treatment of activated carbon is a promising method for enhancing CO2 capture.

Polycaprolactone scaffold surface modification with soft X-ray/extreme ultraviolet (SXR/EUV) radiation and low-temperature oxygen and nitrogen plasma for biomedical applications

Modification of the surfaces of polymeric scaffolds is often required to make the material suitable for specific tissue engineering applications. Physico-chemical properties of scaffolds can be altered using various methods, such as plasma treatment, laser processing, chemical modifications, grafting with nanoparticles, or surface coating. In this paper physico-chemical modification of polycaprolactone (PCL) surface fibers was performed by exposing PCL samples to simultaneous soft X-ray/extreme ultraviolet (SXR/EUV) radiation and low-temperature, SXR/EUV-induced, nitrogen, and oxygen plasmas. The physical and chemical changes on modified PCL surfaces were examined using a scanning electron microscope and X-ray photoelectron spectroscopy, respectively. The effects of physico-chemical scaffold surface changes were verified with biological tests, i.e., MTT assay and immunofluorescence on murine osteoblast cell line (7F2). It was found that exposure of scaffolds to ionizing radiation and low-temperature plasmas induced strong chemical changes on their surface, i.e., appearance of various new chemical groups. Also, smoothing of the surface of PCL fibers, i.e., disappearance or significant reduction of the size of micropores on their fibers was also observed. Increased viability and adhesion of 7F2 osteoblasts on modified PCL samples after 24 h cell culture compared to non-treated PCL was also confirmed.Graphical abstract

Coordinated d-p hybridized hcp@fcc NiRu alloy doped by interstitial atoms for boosting urea-assisted simulated seawater electrolysis at industrial current densities

The production of hydrogen through seawater electrolysis has recently garnered increasing concern. However, hydrogen evolution reaction (HER) by alkaline seawater electrocatalysis is severely impeded by the slow H2O adsorption and H* binding kinetics at industrial current densities. Herein, a face-centered cubic/hexagonal close packed (fcc/hcp) NiRu alloy heterojunction was fabricated on Ni foam (N doped NiRu-inf/NF) by a low-temperature nitrogen plasma activation. Simultaneously, nitrogen atoms are introduced into the alloy to facilitate d-p hybridization. When N doped NiRu-inf/NF is integrated into a dual-electrode cell for urea-assisted seawater electrolysis, it achieves 100 mA cm−2 with an ultra-low voltage of 1.36 V and excellent stability. Density functional theory (DFT) verifies that the robust d-p hybridization among Ni, Ru and N exhibits more energy level matching for H2O molecule adsorption at the Ru sites, while simultaneously reducing the interaction between H* and Ni sites in N-doped NiRu-inf.

Phase engineering and N doping modulated MoSe2 nanosheets for large-current–density hydrogen evolution in simulated seawater

Molybdenum selenide (MoSe2) is considered to be a promising catalyst for seawater hydrogen evolution, but its catalytic activity falls far short of requirements due to its inert surface. Here, self-supported N-doped 1T@2H-MoSe2/N doped carbon paper (N-MoSe2/NCP) was fabricated by a novel low-temperature nitrogen plasma strategy. In alkaline simulated seawater, the optimized N-MoSe2/NCP-30 only requires an overpotential of 274 mV to reach −200 mA cm−2 with Tafel slope of 54.7 mV dec-1, and exhibits stability over 24 h. This work proposes that the introduction of 1 T phase and N dopant into 2H-MoSe2 using low-temperature plasma strategy can significantly facilitate the exposure of abundant active edge sites and boost the conductivity of MoSe2.

Ferroelectric memory devices using hafnium aluminum oxides and remote plasma-treated electrodes for sustainable energy-efficient electronics

In this work, we adopt a low-temperature sustainable plasma treatment approach for the fabrication of ferroelectric memory devices. From our experimental results, we found that the ferroelectric polarization characteristics of HfAlOx ferroelectric device could be further improved by using low-temperature nitrogen plasma treatment on bottom TiN electrode for surface modification. The low-temperature nitrogen plasma treatment on TiN bottom electrode not only prevent electrode oxidation, but also lowers the generation of defect traps at the interface between ferroelectric HfAlOx and TiN bottom electrode during high-temperature ferroelectric annealing process. Besides, the nitrogen-treated bottom electrode also can improve bias-stress induced instability and cycling endurance of HfAlOx ferroelectric devices due to the effective suppression of randomly distributed defect traps or oxygen vacancies near the surface of bottom electrode.

Harnessing of low-temperature nitrogen plasma technique as an eco-friendly approach for dye-ability of cotton fabric with acid dye

PurposeThe purpose of this paper is to generate nitrogen-containing groups in the cotton fabric surface via low-temperature nitrogen plasma as an eco-friendly physical/zero-effluent process. This was done for rendering cotton dye-able with Acid Blue 284, which in fact does not have any direct affinity to fix on it.Design/methodology/approachDyeing characteristics of the samples such as color strength (K/S), fastness properties to light, rubbing and perspiration and durability, as well as tensile strength, elongation at break, whiteness, weight loss and wettability in addition to zeta potential of the dyed samples, were determined and compared with untreated fabric. Confirmation and characterization of the plasma-treated samples via chemical modifications and zeta potential was also studied using Fourier transform infrared spectroscopy (FTIR) and Malvern Zetasizer instrumental analysis.FindingsThe obtained results of the plasma-treated fabric reflect the following findings: FTIR results indicate the formation of nitrogen-containing groups on cotton fabrics; notable enhancement in the fabric wettability, zeta potential to more positive values and improvement in the dyeability and overall fastness properties of treated cotton fabrics in comparison with untreated fabric; the tensile strength, elongation at break, whiteness and weight % of the plasma treated fabrics are lower than that untreated one; and the durability of the plasma treated fabric decreased with increasing the number of washing cycles.Originality/valueThe novelty addressed here is rendering cotton fabrics dye-able with acid dye via the creation of new cationic nitrogen-containing groups on their surface via nitrogen plasma treatment as an eco-friendly and efficient tool with a physical/zero-effluent process.

Influence of Plasma Treatment Parameters on the Structural-Phase Composition, Hardness, Moisture-Resistance, and Raman-Enhancement Properties of Nitrogen-Containing Titanium Dioxide.

The paper shows, for the first time, the prospects of treatment with a quasi-equilibrium low-temperature nitrogen plasma in an open atmosphere for the formation of super-hard, super-hydrophobic TiN/TiO2 composite coatings with pronounced Raman-enhancement properties. X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy, as well as the analysis of hardness and moisture-resistance properties, are used as analytical research methods. During plasma treatment of titanium films on sapphire with a mass average temperature of 4-6 kK, an X-ray amorphous hydrophilic titanium oxide film with a low nitrogen content is formed. The nitrogen content in titanium oxide films increases with increasing treatment temperature up to 6-7 kK. In this case, an X-ray amorphous hydrophobic film is formed. With a further increase in temperature to 7-10 kK, a TiN/TiO2 composite structure based on polycrystalline rutile is formed with increased hydrophobicity and pronounced Raman enhancement properties due to the effective excitation of surface plasmon polaritons. The presence of the crystalline phase increases the dephasing time, which determines the quality of the resonance and the achievable amplification of the electromagnetic field near the TiN inclusions. All treated films on sapphire have a super-hardness above 25 GPa (Vickers hardness test) due to high grain size, the presence of nitrogen-containing inclusions concentrated along grain boundaries, and compressive stresses.

Facile Synthesis of Ti/TiN/TiON/TiO2 Composite Particles for Plasmon-Enhanced Solar Photocatalytic Decomposition of Methylene Blue

The present work studies the interrelation of the structural-phase composition and morphology of composite Ti/TiN/TiON/TiO2 microparticles with their catalytic properties under UV, visible, and solar light irradiation. An efficient method for the synthesis of composite Ti/TiN/TiON/TiO2 microparticles is proposed. The method uses the effect of low-temperature nitrogen plasma of an electric arc in an open atmosphere on titanium microparticles. Photocatalytic activity of fabricated composite microparticles under visible and sunlight irradiation is demonstrated. The mechanism of photocatalysis is proposed.

Plasmachemical Synthesis of TiC–Mo–Co Nanoparticles with a Core–Shell Structure in a Low-Temperature Nitrogen Plasma

Plasmachemical Synthesis of TiC–Mo–Co Nanoparticles with a Core–Shell Structure in a Low-Temperature Nitrogen Plasma

Composition and structure of «core–shell» nanocrystalline particles based on titanium-molybdenum carbides obtained under the conditions of plasma-chemical synthesis

This paper provides the data on the composition and structure of nanocrystalline particles formed during the plasmachemical synthesis of mechanical mixtures containing TiC, Mo, and Co according to the plasma-induced Ostwald ripeningscheme. The paper was mainly intended to study the structural features and localizations of Mo0.42C0.58 carbide in TiC–Mo and TiC–Mo–Co nanocrystalline «core–shell» structures. As a result of X-ray diffraction and high resolution transmission electron microscopy (HRTEM) studies, it was found that the Mo0.42C0.58 carbide of orthorhombic modification is present in all fractions of TiC–Mo and TiC–Mo–Co mechanical mixtures after Ostwald ripening. Nanocrystalline TiC–Mo fractions and the TiC–Mo–Co mixture subjected to one-time Ostwald ripening from a baghouse filter were used in the electron microscopy study to illustrate the presence of «core–shell» structures where refractory cores are represented by Ti1–nMonCx titanium-molybdenum carbides, and high-contrast metal shells contain Mo, Mo0.42C0.58 and Co. Electron microscope images also showed the localization of orthorhombic Mo0.42C0.58. According to the results obtained, it can be concluded that «core–shell» structures are formed during the extreme exposure in the form of plasma-chemical synthesis of TiC–Mo and TiC–Mo–Co mechanical mixtures in a low-temperature nitrogen plasma. At the same time, it should be added that nanocrystalline compositions with the «core–shell» structure are crystallized in a tangential nitrogen flow at a cooling rate of 105 °C/s with the subsequent separation of products into ultra- and nanodispersed fractions in a vortex-type cyclone and a baghouse filter.

Mechanism of formation of nanocrystalline particles with core-shell structure based on titanium oxynitrides with nickel in the process of plasma-chemical synthesis of TiNi in a low-temperature nitrogen plasma

Mechanism of formation of nanocrystalline particles with core-shell structure based on titanium oxynitrides with nickel in the process of plasma-chemical synthesis of TiNi in a low-temperature nitrogen plasma

Mechanism of liquid-phase interaction between nanocrystalline composition (VC0.40О0.53–C)–C and titanium nickelide

The article considers the possibility of binding free carbon existing in the VC0.40O0.53–Cfree nanocrystalline composition to the carbide phase. This composition is obtained by plasma-chemical synthesis in a low-temperature nitrogen plasma. As a carbide former, titanium was used in the form of its nickelide TiNi, which has a melting point of 1310 °С. Experiments were carried out under vacuum sintering conditions involving the liquid phase at 1500 °C for 40 min. The data obtained in X-ray diffraction, scanning electron microscopy and energy-dispersive analysis were used to determine the phase composition and microstructural features of sintered samples. Liquid-phase interaction between the VC0.40O0.53–Cfree nanocrystalline composition and titanium nickelide, the content of which varied from 10 to 99 wt.%, was studied based on the results of experiments. It was shown that the content of Cfree and VC vanadium carbide increases with the simultaneously increasing TiC content as the TiNi mass content increases in the range of 10–90 wt.%. With a further increase in the titanium nickelide content to 99 wt.%, Ti3Ni4 and Ni3Ti nickelides are present after sintering. The content of free carbon increases to 88 wt.%, and the amount of TiC decreases to 5 wt.%. The data obtained in the course of the study were used to propose various schemes of processes occurring during the (VC0.40O0.53–Cfree)–TiNi liquid phase sintering. In particular, sintering involving the liquid phase proceeds in three stages including TiNi melting, refractory base dissolution, its reprecipitation in the form of TiCx and VCx carbides, and cooling of the resulting composition. It should be noted that the mechanism of liquid-phase interaction during vacuum sintering involving the liquid phase was developed on the basis of the laws presented in the paper by M. Gumenik.

Effect of low temperature nitrogen plasma composition on hydrophilic and hydrophobic properties of coatings nitrided titanium oxide based

Effect of nitrogen plasma composition on structural-phase and elemental composition, topography, mechanical and hydrophobic properties of coatings on the basis of nitrogen-containing titanium oxide during penetration onto sample in open atmosphere is studied. It has been shown that at an equally high microhardness of the order of 25--27 GPa, by controlling the composition of the nitrogen plasma, either hydrophilic (contact angle 73o)) or hydrophobic coatings (contact angle 120o)) can be formed. Keywords: hydrophobicity, hydrophilicity, titanium dioxide, sapphire, low-temperature plasma, nitrogen, contact angle, microhardness.

Formation of titanium-cobalt nitride Ti0.7Co0.3N under plasma-chemical synthesis conditions in a low-temperature nitrogen plasma

Formation of titanium-cobalt nitride Ti0.7Co0.3N under plasma-chemical synthesis conditions in a low-temperature nitrogen plasma

Formation of Superhard Coatings during Treatment of Titanium Films with Low-Temperature Nitrogen Plasma in Open Atmosphere

Formation of Superhard Coatings during Treatment of Titanium Films with Low-Temperature Nitrogen Plasma in Open Atmosphere

Study of physical and mechanical properties of steel after plasma modification of its surface

On the basis of studies of the electrophysical characteristics of a low-temperature nitrogen plasma flow, a procedure for verifying the thermophysical properties and establishing regularities in the formation of the structure, phase composition, and properties of a metal when steels surface is exposed to plasma, plasma exposure modes were determined for modifying the surface of metals and alloys used in various applications, such as nuclear power plants.

Strengthening Thin-Walled Knives with Nitrogen Plasma

Introduction. The completed developments are aimed at creating a new technology for increasing the wear resistance of a thin-walled instrument of complex configuration made of steel 65G for cutting beets at sugar enterprises. The most important requirement to improve the operability and durability of such a tool is the preservation of its profile and cutting edge during operation. Materials and Methods. A new developed equipment and technological process of strengthening using low-temperature nitrogen plasma were used to solve this problem. There have been determined optimal processing parameters that ensure the formation of a quasi-morphic structure on the friction surface that reduces the defectiveness of the cutting edge after its machining and also provides a process of self-sharpening due to tool strengthening on one side. Results. The comparative studies of the friction surface of products after operational tests have shown that their resistance increase significantly when strengthening both new and used products. This is determined by the nature of the quasi-morphic structure formed and the specific relief in friction on the working surface. Discussion and Conclusion. To describe the new process of strengthening thin-walled products, the structure formation on the friction surface was analyzed in detail with the use of metallographic images and its phase relationship variability was estimated by the optic-mathematical analysis of various zones (compression and vacuum) formed as friction bands. This was done trough modeling with the estimation of the distribution density of the conditional colors of the analyzed fragments.

Mechanical Properties of Keratin Composite Films Using Poultry Feathers as Reinforcement Fibers

In this work, the chemical and low temperature nitrogen plasma methods were adopted to treat the raw material, untreated poultry feather (UPF), to obtain thechemically treated poultry feather (CPF), plasma treated poultry feather (PPF) and chemically & plasma treated poultry feather (CPPF), respectively. Then the four kinds of feather fibers were used as reinforcement fibers to prepare feather/keratin composite films with the ratio from 1% to 12% (relative to the mass of keratin in the film), respectively. The effect of feather treatment method and the feather fiber content onthe mechanical properties of films were studied. The results show that UPF has poor enhancement performance in keratin films, and CPF and PPF have better reinforcing effect than UPF. The keratin films reinforced by CPPF have relatively strong breaking strength, indicating that the CPPF plays an active reinforcing role in the composite film and has the most potential as a reinforcement fiber. For all the samples, when the fiber content is around 7%, the composite film has the best mechanical properties.

Формирование сверхтвердых покрытий в процессе обработки низкотемпературной плазмой азота в открытой атмосфере пленок титана

Results of the formation of superhard coatings in the low-temperature nitrogen plasma treatment process in the open atmosphere of titanium films on sapphire substrates are given. It is shown that during plasma treatment a coating of nitrogen-containing TiO2 with rutile structure is formed with a double increase (in comparison with rutile TiO2) of microhardness (up to 27 GPa). The application of this coating leads to hardening of the surface of sapphire plates by 22-23%. High productivity and implementation of synthesis in an open atmosphere make it possible to consider the proposed procedure is promising for the production of superhard coatings with high resistance to oxygen.

Solid Phase Interaction of the Recondensed Finely Dispersed Mixture (VC0.40O0.53–C) with Titanium Hydride

The processing of industrial waste and highly hazardous substances using extreme techniques of formation, in addition to else, of nanocrystalline materials, which include plasmachemical synthesis according to the plasma recondensation scheme in low-temperature nitrogen plasma, is an urgent issue of chemical technology. In the work, an attempt was made to plasma recondensation of a mechanical mixture consisting of crystalline hydrates of the VnOn·xH2O type and gas soot in an 1 : 1 ratio. The solid phase interaction of the VC0.40O0.53–Cfree nanocrystalline mixture with TiH2 hydride in various proportions in the course of high-temperature vacuum sintering was studied. Based on the data of X-ray diffraction, scanning electron microscopy, and EDX analysis, the main patterns of solid phase interaction in the system (VC0.40O0.53–Cfree)–TiH2 were described, and schemes of the processes were proposed occurring during sintering.