Nitrogen Plasma Research Articles

Effect of N plasma immersion ion implantation (N-PIII) on the microstructure and mechanical properties of 8Cr4Mo4V steel

To enhance the surface hardness and wear resistance of 8Cr4Mo4V steel, nitrogen plasma immersion ion implantation (N-PIII) was carried out, under various nominal implantation energies, in this study. Additionally, the microstructure and mechanical properties of the steel were analyzed. The results indicated that the depth of the nitrogen ion-implanted layer escalated with the specified implantation energy, reaching 140 nm for a 50 keV sample. Nitrogen was present within the implanted layer in the martensite lattice as a solute, and also in the form of nitrides along with alloying elements. Moreover, a nanocrystalline layer approximately 40–70 nm thick also formed at the sample surface. As the implantation energy increased, both the surface roughness and residual stress of the sample initially increased before declining, whereas the surface hardness and modulus exhibited a gradual increase. After the 50 keV N-PIII treatment, the surface hardness of the sample increased by 39 %, which caused a remarkable reduction in the friction coefficient, and the wear amount was also reduced by about 40 %. This work systematically establishes the relationship between the surface microstructures, surface morphology, and mechanical properties of implanted 8Cr steel, and significantly improves its surface hardness and wear resistance.

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

A biocompatible nanofibers modified by plasma for osteoblast growth differentiation.

This work employs nitrogen plasma immersion ion implantation (PIII) to modify electrospinning polylactic acid membranes and immobilizes essential fibroblast growth factors(bFGF) by forming cross-linking bonds. The study investigates the modified membranes' surface characteristics and the stimulatory effects of cross-linked bFGF polylactic acid membranes on osteoblast and fibroblast proliferation. The PIII process occurs under low vacuum conditions and is controlled by processing time and power pulse width. The experimental results indicate that, within a 400-second N2-PIII treatment, the spun fibers remain undamaged, demonstrating an increase in hydrophilicity (from 117° to 38°/36°) and nitrogen content (from 0% to 7.54%/8.05%). XPS analysis suggests the formation of a C-N-C=O cross-linked bond. Cell culture and activity assessments indicate that the PIII-treated and cross-linked bFGF film exhibits significantly higher cell growth activity (P<0.05) than the untreated group. These intergroup differences are attributed to the surface cross-linking bond content. In osteogenic induction, the results for each day show that the treated group performs better. However, the intergroup disparities within the cross-linked bFGF group disappear with prolonged culture time due to the rapid osteogenesis prompted by bFGF. The findings suggest that PIII treatment of electrospinning polylactic acid membranes holds promise in promoting osteogenesis in bone tissue scaffolds.

Contribution of vibrational excited molecular nitrogen to ammonia synthesis using an atmospheric-pressure plasma jet

The contribution of atomic nitrogen is fairly possible in plasma-assisted catalytic synthesis of ammonia since it has high adsorption probabilities on solid surfaces. On the other hand, recently, the contribution of vibrational excited molecular nitrogen to ammonia synthesis has been discussed. In this work, we compared the fluxes of atomic nitrogen and vibrational excited molecular nitrogen with the rate of plasma-assisted ammonia synthesis. We employed an atmospheric-pressure nitrogen plasma jet, and the spatial afterglow of the plasma jet and a hydrogen flow irradiated the surface of a ruthenium catalyst. The fluxes of atomic nitrogen and vibrational excited molecular nitrogen were measured by two-photon absorption laser-induced fluorescence spectroscopy and laser Raman scattering, respectively. The synthesis rate of ammonia had a positive correlation with the flux of vibrational excited molecular nitrogen, while the variation of the synthesis rate with the gas flow rate was opposite to the flux of atomic nitrogen. The experimental results indicate the contribution of vibrational excited molecular nitrogen to the synthesis of ammonia using the atmospheric-pressure plasma, where the flux of vibrational excited molecular nitrogen is more than four orders of magnitude higher than that of atomic nitrogen.

Development of RF plasma generator based on Class E Power Amplifier

Abstract The plasma produced at 2 MHz radio frequency has substantial energy release stability and can be used to modify a material’s surface. The objective of this research is to create a plasma generator operating at a radio frequency of 2 MHz and examine how voltage affects the plasma spectrum that is generated. An AD9833 frequency generator, a class E amplifier, and impedance matching are used in the design of a 2 MHz radio frequency plasma generator as power amplifiers to create plasma. Variations in voltage, gas, and gas flow have been used. The input voltage variations used were 10V and 15V from the power supply. Two different media, free air (atmospheric gas) and argon gas flow, are used for plasma generation. In free air, the plasma formed is Nitrogen plasma with a wavelength of 300 to 380 nm. Argon gas flow is given a variation of Argon gas rate of 2 LPM, and 3 LPM. The plasma formed is Argon plasma with a wavelength of 700 to 850 nm.

Designing innovative PAni-based adsorbents for CO2 capture via in-situ nitrogen plasma modification for sustainable development

Carbon dioxide (CO2) capture is a critical strategy in the fight against climate change. By implementing this innovative technology, CO2 emissions from diverse sources will be captured and neutralized, thereby mitigating global warming. For this purpose, novel sorbents were developed in this work by loading TiO2 and ZnO nanofillers into a polyaniline (PAni) system to form PAni–TiO2 (PT) and PAni–ZnO (PZ) composites. Following that, in-situ nitrogen (N2) plasma treatments were applied for 5 min to improve their surface nature and physiochemical properties. The CO2 capture qualities of modified PT and PZ sorbents were investigated, as well as physical assessments of their microstructure, nuclear magnetic resonance (NMR), morphology, contact angle, roughness, electrical optical, reactivity, stability, and adsorption capability, hardness, softness and electrophilicity properties. Bombardment of high-energy plasma species for 5 min was sufficient to optimize the crystallite size and crystallinity degree in both the PT5 and PZ5 systems. These enhancements may be related to the growth of protonated benzoid rings -NH+- as a result of plasma modifications to the structure of PAni and its transformation into emerald salt. In a similar vein, the SEM micrographs, porous topography and hydrophilic nature of the PAni composites varied with respect to the type of nanofillers and plasma level. The plasma treatment provided additional oxygen-containing functional groups as active sites for chemical interactions, including CO2 via chemisorption or physisorption, facilitating further reduction. Additionally, plasma activities assisted in shifting to a rougher surface (i.e.,Ra = 3.83 µm) as well as optimizing the energy band gap (1.57 eV), which can accommodate more CO2 molecules, thereby improving the capture efficiency. Moreover, the findings indicate that PZ5 is more desirable for CO2 adsorption since it possesses a 2.52-fold greater CO2 adsorption energy (-0.079 a.u) than pristine PZ0. In the future, our work opens up exciting new prospects to achieve desired performance from CO2 capturing compounds utilizing plasma technology.

Surface Functionalization of Quasi-Two-Dimensional MoS2 in Nitrogen and Oxygen Plasma

Surface Functionalization of Quasi-Two-Dimensional MoS2 in Nitrogen and Oxygen Plasma

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.

The Conversion of Li2SnO3 Li-Ion Hybrid Supercapacitors from Pastes Containing LiCl-SnCl2 Liquid Precursors Using an Atmospheric-Pressure Plasma Jet

We fabricate lithium tin-based oxide Li2SnO3 on carbon cloth from a gel-state precursor containing LiCl and SnCl2·2H2O using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ treatment provides both a high-temperature environment for the conversion of precursor into Li2SnO3 and nitrogen plasma reactive species for electrode surface modification. Here, the best electrochemical performance for the Li2SnO3 Li-ion hybrid supercapacitors (Li–HSCs) is achieved with 480 s of APPJ processing. The areal capacity of the 480 s APPJ-processed Li2SnO3 Li–HSCs reached 46.113 mC/cm2. The results indicate that APPJ is an effective tool for the rapid conversion processing of Li2SnO3 electrodes for Li–HSCs.

Diurnal rhythm of aquaporins expression and function in the kidney

Aquaporins (AQPs) are a protein family that plays a major role in maintaining water homeostasis. Aquaporin 2 (AQP2) and 3 (AQP3) are expressed on the collecting duct and regulated by the antidiuretic hormone, arginine vasopressin (AVP). AVP binds to its receptor on the collecting duct leading to increased expression of AQP2 on the apical membrane and AQP3 on the basolateral membrane to drive water reabsorption and promote urine concentration. We know that there are biological circadian rhythms that are critical for maintaining homeostasis. Therefore, we aimed to determine AQP2 and AQP3 expression and urine concentrating ability during their active time and inactive time in male and female mice. We hypothesize that there is a diurnal pattern in AQP2 and AQP3 expression or abundance leading to the variation of urine concentrating ability. Male (n=12) and female (n=12) C57BL/6J mice (10-11 weeks old) were euthanized in the middle of their active period (midnight) or the middle of their inactive period (noon). Spot urine osmolality was determined using a freezing point osmometer. Plasma sodium, chloride, and blood urea nitrogen (BUN) plasma concentration using an i-STAT blood analyzer. We localized aquaporins in kidney sections by using a diaminobenzidine chromagen method with antibodies against AQP2, AQP2 pS256 (an activation site), AQP2 pS261(an inhibitory site), and AQP3. Then, using a blinded method, the program Fiji Image J was used to quantify aquaporins on collecting ducts by using the integrated density (IntDen) parameter after calibrating into optical density (OD). We found that urine osmolality of control mice during their active period (2449±442.3 mOsm/ kg) was higher than that in the inactive time (1684±705.6 mOsm/kg, p = 0.0043). The plasma sodium concentration was higher in the active time (145±1.782 mmol/ L) than in the inactive time (142.9±1.311 mmol/L) with p = 0.0026. The plasma chloride (Cl−) and plasma BUN were also higher in the active time (Cl− = 115.2±1.4 mmol/L; BUN = 23±3.6 mmol/L) than in the inactive time mice (Cl− = 111±2.0 mmol/L, p &lt; 0.0001; BUN = 19.75±2.5 mmol/L, p = 0.0187). AQP2 was differentially expressed. During the active period, in both male and female mice, AQP2 was highly expressed in the collecting duct but was obviously reduced during the inactive period (active time = 4083±1006 OD; inactive time = 1243±608 OD, p &lt; 0.001). Moreover, AQP2 activation as determined by phosphorylation S256, was also greater during the active period (1148±404 OD) than inactive (221±96 OD, p = 0.002). Interestingly, the inhibitory site, phosphorylation of S261, was also greater during the active period (592 ± 378 OD) than the inactive period (162 ± 36 OD, p = 0.039). We found no significant difference in AQP3 localization or abundance. In summary, we showed that there is diurnal variability in urine osmolality (higher in their active period) that is supported by increased AQP2 expression during the active period of the mice, regardless of sex. Future studies will aim to determine if antagonizing and stimulating the vasopressin 2 receptor affects urine concentration in a diurnal manner. Intramural UAB funds to KAH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Catalyst electrode based on in-situ grown Pt nanowires

The plasma treatment method, which is a simple and ecologically benign procedure, is used to treat the gas diffusion layer (GDL) surface for proton exchange membrane fuel cell (PEMFC) application. The surface plasma treatment greatly aids in the uniform in situ growth of platinum (Pt) nanowires on the GDL surface to fabricate gas diffusion electrodes (GDEs). Helium (He) and nitrogen (N2) are used, and the outcomes from utilising each gas independently are compared at four different durations between 30 s, 60 s, 90 s, and 120 s. Membrane Electrode Assemblies (MEAs) are fabricated with the as-prepared GDEs and tested in H2/air PEMFC single cells. The testing results show the nitrogen plasma applied to the GDE surface for 60 s produces the best power performance with a current density of 1372.7 mA/cm2 at 0.6V.

Nickel nitride-mediated nitric oxide generation for combating implant-associated infections

NiTi alloys are widely used in the fabrication of biomedical implants, and it is essential to endow them with selective antibacterial properties to avoid implant-associated infection. In this study, nickel nitride (Ni3N), as a promising new inorganic nitric oxide (NO) donor, was in situ constructed on the surface of NiTi alloys through a straightforward two-step plasma immersion ion implantation (PIII) strategy. Nickel sites were first exposed by physical bombardment with argon or metal plasma, followed by reaction with nitrogen plasma to form Ni3N. Ni3N can disrupt the transmembrane proton electrochemical gradient by capturing protons to produce ammonia species (NHx), resulting in the accumulation of reactive oxygen species (ROS) as a result of bacterial metabolic disruption. On the other hand, the generated NHx can further react with ROS to produce NO and reactive nitrogen species (RNS). As a result, the Ni3N films exhibited more than 99 % antibacterial efficiency against both gram-negative and gram-positive bacteria. They also demonstrated effective antibacterial properties in a rat subcutaneous implant model. In addition, the modified NiTi alloys exhibit good corrosion resistance and cytocompatibility. This study provides a green, safe, and inexpensive method for constructing metal nitride films on implant surfaces and offers new ideas for the clinical design and fabrication of novel antibacterial implants.

Nitrogen plasma treated cotton fabrics coated with SiO2 followed by RGO deposition for water purification process

Experimental investigations have been carried out to modify the surface properties of Cotton fabrics using low temperature DC glow discharge nitrogen plasma. Plasma treatment is an eco-friendly, dry and clean process over wet chemical methods and does not suffer from any environmental and health concerns [1]. The important plasma parameters such as power and working pressure are kept constant with various treatment times (5, 15, 30, and 60 mins). The plasma-treated cotton fabrics are optimized by XRD, FTIR, and SEM. A comparative study has been done for the untreated and different treated fibers. Pure SiO2 is coated on untreated and nitrogen plasma treated cotton fabrics by sputtering method. The samples are coated for different sputtering times (10 and 30 min). Finally, Reduced Graphene Oxide (RGO) is coated on plasma treated SiO2 deposited fabrics. RGO is prepared by modified hummers methods [2]. Our results provide a way to develop a filter for water purification.

Influence of Oxygen/Argon/Nitrogen multi-component plasma modification on interlayer toughening of UHMWPE fiber reinforced composites

The study reveals the influence of glow discharged three gas sources of Oxygen/Argon/Nitrogen plasma modification on interlayer toughening of ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composite. The failure modes under bending, tensile and interlayer fracture toughness testing were analyzed through acoustic emission (AE) technology. The results showed that Oxygen/Argon/Nitrogen multi-component plasma modified fiber introduced more hydrophilic groups such as hydrogen and hydroxyl groups, and significantly enhanced the binding of fiber and matrix. The GⅠC (Mode-I interlaminar fracture toughness) of multi-component plasma modified composites exhibited increased by 61.67 %, 40.88 % and 18.01 % compared to untreated, Oxygen and Oxygen/Argon plasma, respectively, while GⅡC (Mode-II interlaminar fracture toughness) increased by 38.57 %, 25.57 % and 23.09 %. AE cluster analysis exhibited that multi-component plasma modified composites formed an energy dissipation mechanism dominated by fiber breakage. Additionally, the oxygen, argon, and nitrogen plasma modification have a synergistic effect on interlayer toughening.

Depth profiling of microwave nitrogen-terminated polycrystalline diamond surfaces by energy-dependent X-ray photoelectron spectroscopy

Nitrogen-terminated diamonds hold promise for stabilizing near-surface NV− centers, which is essential for reliable quantum sensing. Among various surface preparation methods, microwave (MW) nitrogen plasma, known for its minimal surface damage, appears as the most effective choice. In this investigation, we explore the nature of nitrogen bonding of polycrystalline diamond (PCD) surfaces exposed to MW nitrogen plasma using X-ray Photoelectron Spectroscopy (XPS) depth profiling and Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the C K- and N K-edges. XPS depth profiling with atomic resolution, achieved by varying the probing photon energy using synchrotron radiation and supported by a physical model considering the associated inelastic mean free path, suggests a surface of almost fully saturated nitrogen in two main bonding configurations of similar contribution and a low coverage of ∼5 % of graphene-like islands residing atop the nitrogen-terminated diamond surface. The thermal stability of these surface groups is monitored by in situ annealing up to 700 °C. The depth profiles reveal that nitrogen atoms do not diffuse in the diamond crystal, resulting in excellent diamond crystallinity in the first atomic planes below the surface. C K-edge NEXAFS analysis reveals the position of unoccupied surface states within the diamond bandgap, opening new perspective on the stabilization of near-surface NV− centers.

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.

Improvement of the electrochemical properties of Li/CFx primary batteries induced by Nitrogen plasma treatment from silica and carbon fluoride

Improvement of the electrochemical properties of Li/CFx primary batteries induced by Nitrogen plasma treatment from silica and carbon fluoride

Role of plasma process gas on permeate flux augmentation of cellulose nitrate membrane for mud water treatment

A comparative study between Nitrogen (N2) and Argon (Ar) plasma is carried out to investigate its effect on surface morphology, hydrophilicity, permeate flux and ageing of cellulose nitrate polymeric membranes in the present work. Langmuir probe and Optical Emission Spectroscopy are used to characterize the plasma. The SEM analysis reveals the noticeable macro-void creations and pore enlargement for both N2 and Ar plasma. The AFM analysis shows a higher surface roughness for Ar plasma treatment as compared to N2 plasma treatment. XPS analysis confirms the changes in the polymer matrix along with the incorporation of various functional groups on the membrane surface as a result of the plasma treatment. A better hydrophilic nature with prolonged plasma treatment is observed for Ar plasma as compared to N2 plasma treatment. The present results show a higher permeate flux with a high rejection rate for Ar plasma treatment in comparison to N2 plasma, which might be due to the pore size and pore area enlargement of the membrane. The hydrophobic recovery for both the plasma-treated membranes is found significant for the initial ageing period of 7 days and found almost stable in nature after 7 days. A diffusion-based theoretical model is developed to study the hydrophobic recovery of plasma-treated membranes. A strong alignment between experimental and theoretical results is observed in the present work. The Cake Filtration model, derived from the Hermia model, is identified as the most suitable model for describing the fouling mechanisms for the present work.

Power-efficient and high-performance potential of pentacene transistors enabled by metal-nitride gate insulators fabricated with nitrogen plasma

The demand for next-generation organic field-effect transistors (OFETs) with low operating voltage is becoming gradually attractive in many application areas, such as flexible/wearable medical sensors and stretchable electronics. While using high dielectric materials is a potent approach, it often results in a decline in field-effect mobility or on/off ratio. Unfortunately, achieving low-voltage operation has hindered practical applications, compromising device performance. Here, we discovered for the first time a novel class of low-driving voltage pentacene transistors adopting gate insulators composed of nitrogen-plasma-reacted AlNx, TiNx, and TaNx. This exciting discovery is simple, affordable, environmentally friendly, and secure. X-ray photoelectron spectrometer (XPS) analysis reveals that the as-formed metal nitrides are composited with certain native oxide components, exhibiting outstanding leakage current blocking capacity and a high dielectric constant. Further, the surface energy of metal nitrides was altered by applying a thin layer of poly-(4-vinylphenol) (PVP). This modification improved the growth of pentacene grains and the insulator/pentacene interface. The best devices by comprehensive evaluation, the TiNx samples, achieve a high average of field-effect mobility ∼1.41 cm2/Vs, a subthreshold swing of 0.19 V/dec, an on/off current ratio of ∼104, and a turn-on voltage close to 0 V, which shows promising potential candidates for the flexible electronic devices, optoelectronic devices, and neuromorphic application.