Nitrogen Atmospheric Pressure Plasma Jet Research Articles

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.

Ultrafast Fabrication of H2SO4, LiCl, and Li2SO4 Gel Electrolyte Supercapacitors with Reduced Graphene Oxide (rGO)-LiMnOx Electrodes Processed Using Atmospheric-Pressure Plasma Jet.

Pastes containing reduced graphene oxide (rGO) and LiCl-Mn(NO3)2·4H2O are screen-printed on a carbon cloth substrate and then calcined using a nitrogen atmospheric-pressure plasma jet (APPJ) for conversion into rGO-LiMnOx nanocomposites. The APPJ processing time is within 300 s. RGO-LiMnOx on carbon cloth is used to sandwich H2SO4, LiCl, or Li2SO4 gel electrolytes to form hybrid supercapacitors (HSCs). The areal capacitance, energy density, and cycling stability of the HSCs are evaluated using electrochemical measurement. The HSC utilizing the Li2SO4 gel electrolyte exhibits enhanced electrode-electrolyte interface reactions and increased effective surface area due to its high pseudocapacitance (PC) ratio and lithium ion migration rate. As a result, it demonstrates the highest areal capacitance and energy density. The coupling of charges generated by embedded lithium ions with the electric double-layer capacitance (EDLC) further contributed to the significant overall capacitance enhancement. Conversely, the HSC with the H2SO4 gel electrolyte exhibits better cycling stability. Our findings shed light on the interplay between gel electrolytes and electrode materials, offering insights into the design and optimization of high-performance HSCs.

Influence of Oxygen Impurity on Nitrogen Atmospheric-Pressure Plasma Jet

This study discussed the effect of oxygen impurity in the inlet gas of a nitrogen atmospheric pressure plasma jet (APPJ). A numerical model that takes into account the fluid dynamics, heat transfer, mass transfer, diffusion, and chemical reactions was developed to simulate the nitrogen APPJ. Further, a DC nitrogen APPJ experiment was performed to verify the plasma temperature characteristics on the treated surface. The plasma temperature decreased with an increase in the oxygen impurity. Moreover, the oxygen impurity influenced the related excited and neutral species. Specifically, with added oxygen impurity, N-related species decreased whereas O- and NOx-related species increased. Because the excited state species constitutes the most important reactant in APPJ treatment, this study could serve as a reference for the adjustment of a nitrogen APPJ.

LiMn2O4 Li-ion hybrid supercapacitors processed by nitrogen atmospheric-pressure plasma jet

LiCl–Mn(NO3)2·4H2O pastes were screen-printed on a carbon cloth substrate and furnace-calcined to convert them into LiMn2O4. The LiMn2O4 electrode was then post-processed using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ processing created oxygen vacancy defects on the electrode surface. Electrochemical tests of the Li-ion hybrid supercapacitors (Li–HSCs) were performed by cyclic voltammetry (CV) and galvanostatic charging/discharging (GCD) in 1-M Li2SO4 aqueous solution. The results indicate that proper APPJ treatment optimizes the Li–HSCs performance, whereas excessive APPJ treatment may cause material damage. After 3-min APPJ treatment at 620 °C, the Li–HSCs exhibited a maximum areal capacitance of 87.96 mF/cm2 with capacitance retention of 124.8% after a 1000-cycle CV test.

Carbon Dioxide Tornado-Type Atmospheric-Pressure-Plasma-Jet-Processed rGO-SnO2 Nanocomposites for Symmetric Supercapacitors.

Pastes containing reduced graphene oxide (rGO) and SnCl2 solution were screen printed on carbon cloth and then calcined using a CO2 tornado-type atmospheric-pressure plasma jet (APPJ). The tornado circulation of the plasma gas enhances the mixing of the reactive plasma species and thus ensures better reaction uniformity. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were performed to characterize the synthesized rGO-SnO2 nanocomposites on carbon cloth. After CO2 tornado-type APPJ treatment, the pastes were converted into rGO-SnO2 nanocomposites for use as the active electrode materials of polyvinyl alcohol (PVA)-H2SO4 gel-electrolyte flexible supercapacitors (SCs). Various APPJ scanning times were tested to obtain SCs with optimized performance. With seven APPJ scans, the SC achieved the best areal capacitance of 37.17 mF/cm2 in Galvanostatic charging/discharging (GCD) and a capacitance retention rate of 84.2% after 10,000-cycle cyclic voltammetry (CV) tests. The capacitance contribution ratio, calculated as pseudocapacitance/electrical double layer capacitance (PC/EDLC), is ~50/50 as analyzed by the Trasatti method. GCD data were also analyzed to obtain Ragone plots; these indicated an energy density comparable to those of SCs processed using a fixed-point nitrogen APPJ in our previous study.

Investigating the effect of water‐mixing nitrogen atmospheric pressure plasma jet on polyether‐ether‐ketone and time stability under different conditions

AbstractPossessing excellent properties including good biocompatibility, high strength, and stiffness, polyether‐ether‐ketone (PEEK) has significant application values in medical and industrial fields. However, the relatively poor wettability and low adhesion limit its further applications. Atmospheric pressure plasma jet (APPJ) has been utilized for adjusting PEEK properties, but better hydrophilization effect and time stability after treatment are still urgently needed. In this paper, we employ a water‐mixing nitrogen (N2H2O) APPJ to process PEEK, and surface wettability can be effectively improved (contact angle ~18° within 2 min, distance between sample and nozzle outlet: 10 mm) without inducing obvious microstructure damages. Additionally, after storing for 40 days, the sample treated by N2H2O APPJ also possessed better wettability (~54°) compared with that treated by N2 APPJ (~65°). On the basis of this low‐damage and high‐efficient modification method, we perform aging experiments under different conditions (different temperatures 25, −10°C; and low vacuum condition: 50 kPa) to determine a relatively optimum storing condition for this method. The experiment results indicate that low temperature and vacuum are conducive to retaining the plasma‐induced wettability (~34°). The treatment method and storing conditions for PEEK presented here may facilitate the application of PEEK in various fields.

Flexible rGO-SnO2 supercapacitors converted from pastes containing SnCl2 liquid precursor using atmospheric-pressure plasma jet

Reduced graphene oxide (rGO)-SnO2 nanocomposites are fabricated on carbon cloth from screen-printed pastes containing rGO nanoflakes and SnCl2 liquid precursor by using a nitrogen atmospheric-pressure plasma jet (APPJ). RGO-SnO2-coated carbon cloth is then used as the electrode of gel-electrolyte supercapacitors (SCs). Experiments conducted with various APPJ processing times suggest that the optimal APPJ processing time is 300 s. Cyclic voltammetry (CV) measurements indicate that 300-s APPJ processing results in the best areal capacitance of 97.53 mF/cm2. The capacitance retention rate is ~85% after a 10,000-cycle CV test. Further, capacitance increases by 11% after a 1000-cycle bending test under a bending radius of 7.5 mm, possibly owing to the better electrolyte/electrode contact and decrease in the charge transport resistance after mechanical bending. This study also characterized APPJ-processed rGO-SnO2 nanocomposites by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, Raman spectroscopy, and water contact angle measurements.

Concentration effect on properties of Pt-NiOx nanocompounds converted from mixed chloroplatinic acid and nickel acetate precursor films using an atmospheric-pressure plasma jet

A direct current-pulse nitrogen atmospheric-pressure plasma jet (APPJ) is used to convert Pt-NiOx nanocompounds from liquid precursor films consisting of a mixture of chloroplatinic acid and nickel acetate. The Pt-NiOx nanoparticles are well-distributed on the fluorine-doped tin oxide (FTO) glass substrates. X-ray photoelectron spectroscopy results indicate that the reaction product mainly contains metallic Pt and oxidized Ni. Electrochemical impedance spectroscopy and Tafel experiments reveal an improvement in electrochemical catalytic effects. The APPJ-processed Pt-NiOx nanocompounds on FTO glass substrates are used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). J − V curves indicate that DSSCs with 5-s APPJ-processed Pt-NiOx CEs showed significantly improved performance. The sample properties become stable after ∼45 s of APPJ calcination. Precursor solutions with three different mole ratios of chloroplatinic acid and nickel acetate are investigated. With the addition of an adequate amount of oxidized nickel, the transfer charge current density and electrochemical catalytic effects are enhanced.

Large-Scale Image Analysis for Investigating Spatio-Temporal Changes in Nuclear DNA Damage Caused by Nitrogen Atmospheric Pressure Plasma Jets.

The effective clinical application of atmospheric pressure plasma jet (APPJ) treatments requires a well-founded methodology that can describe the interactions between the plasma jet and a treated sample and the temporal and spatial changes that result from the treatment. In this study, we developed a large-scale image analysis method to identify the cell-cycle stage and quantify damage to nuclear DNA in single cells. The method was then tested and used to examine spatio-temporal distributions of nuclear DNA damage in two cell lines from the same anatomic location, namely the oral cavity, after treatment with a nitrogen APPJ. One cell line was malignant, and the other, nonmalignant. The results showed that DNA damage in cancer cells was maximized at the plasma jet treatment region, where the APPJ directly contacted the sample, and declined radially outward. As incubation continued, DNA damage in cancer cells decreased slightly over the first 4 h before rapidly decreasing by approximately 60% at 8 h post-treatment. In nonmalignant cells, no damage was observed within 1 h after treatment, but damage was detected 2 h after treatment. Notably, the damage was 5-fold less than that detected in irradiated cancer cells. Moreover, examining damage with respect to the cell cycle showed that S phase cells were more susceptible to DNA damage than either G1 or G2 phase cells. The proposed methodology for large-scale image analysis is not limited to APPJ post-treatment applications and can be utilized to evaluate biological samples affected by any type of radiation, and, more so, the cell-cycle classification can be used on any cell type with any nuclear DNA staining.

Surface Modification of FeCoNiCr Medium-Entropy Alloy (MEA) Using Octadecyltrichlorosilane and Atmospheric-Pressure Plasma Jet.

Surface condition and corrosion resistance are major concerns when metallic materials are going to be utilized for applications. In this study, FeCoNiCr medium-entropy alloy (MEA) is first treated with a nitrogen atmospheric-pressure plasma jet (APPJ) and then coated with octadecyltrichlorosilane (OTS) for the surface modification. The hydrophobicity of the FeCoNiCr MEA was effectively improved by OTS-coating treatment, APPJ treatment, or the combination of both treatments (OTS-coated APPJ-treated), which increased the water contact angle from 54.49° of the bare MEA to 70.56°, 93.94°, and 88.42°, respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy tests demonstrate that the APPJ-treated FeCoNiCr MEA exhibits the best anti-corrosion properties. X-ray photoelectron spectroscopy reveals that APPJ treatment at 700 °C oxidizes all the alloying elements in the FeCoNiCr MEA, which demonstrates that a short APPJ treatment of two-minute is effective in forming a metal oxide layer on the surface to improve the corrosion resistance of FeCoNiCr MEA. These results provide a convenient and rapid method for improving surface properties of FeCoNiCr MEA.

Flexible reduced graphene oxide supercapacitors processed using atmospheric-pressure plasma jet under various temperatures adjusted by flow rate and jet-substrate distance

We vary the substrate temperature by adjusting the nitrogen flow rate and jet-substrate distance during nitrogen atmospheric-pressure plasma jet (APPJ) processing of screen-printed reduced graphene oxides (rGOs) on carbon cloth. The APPJ-processed rGOs on carbon cloth are then used as electrodes for supercapacitors. Increasing the nitrogen flow rate could reduce the gas temperature and enhance the reactivity of the reactive plasma species. Typically, lowering the temperature slows down the chemical reaction; however, increased reactivity of the reactive plasma species at the same jet-substrate distance could compensate the temperature effect. A nitrogen APPJ could improve the wettability of the screen-printed rGOs on carbon cloth. We found that 20-s APPJ treatment increases the areal capacitance from 6.2 mF cm−2 (without APPJ treatment) to 22.4 mF cm−2 (700 °C, 30 slm), as evaluated by galvanostatic charging/discharging (GCD) measurements under a constant current of 0.25 mA. Further, 20-s nitrogen APPJ processing at temperatures of ∼600 °C–700 °C could obtain the best areal capacitance value. The capacitance value of the fabricated flexible rGO supercapacitor remains at similar level after 1000-cycle mechanical bending test with a bending radius of 5 mm.

Influence of water addition on the modification of polyethylene surface by nitrogen atmospheric pressure plasma jet

ABSTRACTPolyethylene (PE) has many excellent material properties (low density, high flexibility, good chemical resistance, etc.), and is widely used in industrial and medical fields. However, the practical applications of PE are sometimes limited due to its poor wettability. In this article, we employ pure nitrogen atmospheric pressure plasma jet (APPJ) and N2‐H2O APPJ to hydrophilize PE surfaces. Wettability, time stability, chemical composition, micromorphology, and mechanical properties of the treated surfaces are investigated by contact angle measurement, X‐ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and electric digital display push–pull machine. The pure nitrogen APPJ can hydrophilize PE surfaces without inducing obvious microstructure changes, and relatively better wettability (water contact angle = 13°) could thereby be achieved. On the other hand, the N2‐H2O APPJ creates micro/nanoscale pores on the treated hydrophilic surfaces, contributing to the better time stability and lower tensile strength. The results reported here clearly demonstrate the great potential of nitrogen APPJs with different water mixing ratios in controlling surface wettability and microstructures of polymer surfaces. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47136.

Time Evolution Characterization of Atmospheric-Pressure Plasma Jet (APPJ)-Synthesized Pt-SnOx Catalysts

We characterize the time evolution (≤120 s) of atmospheric-pressure plasma jet (APPJ)-synthesized Pt-SnOx catalysts. A mixture precursor solution consisting of chloroplatinic acid and tin(II) chloride is spin-coated on fluorine-doped tin oxide (FTO) glass substrates, following which APPJ is used for converting the spin-coated precursors. X-ray photoelectron spectroscopy (XPS) indicates the conversion of a large portion of metallic Pt and a small portion of metallic Sn (most Sn is in oxidation states) from the precursors with 120 s APPJ processing. The dye-sensitized solar cell (DSSC) efficiency with APPJ-synthesized Pt-SnOx CEs is improved greatly with only 5 s of APPJ processing. Electrochemical impedance spectroscopy (EIS) and Tafel experiments confirm the catalytic activities of Pt-SnOx catalysts. The DSSC performance can be improved with a short APPJ processing time, suggesting that a DC-pulse nitrogen APPJ can be an efficient tool for rapidly synthesizing catalytic Pt-SnOx counter electrodes (CEs) for DSSCs.

Nitrogen DC-pulse atmospheric-pressure-plasma jet (APPJ)-processed reduced graphene oxide (rGO)‑carbon black (CB) nanocomposite electrodes for supercapacitor applications

This study compares supercapacitors with reduced graphene oxide (rGO)‑carbon black (CB) and CB nanocomposite coated carbon cloth electrodes. We use a nitrogen DC-pulse atmospheric pressure plasma jet (APPJ) to process the electrodes. The APPJ processing time is <40 s. Nitrogen APPJ burns off organic binders to create nanoporous structures. Replacing part of the CB with rGO nano-flakes can increase the overall surface area to improve the supercapacitive performance. Specifically, by replacing 50 wt% of CBs with rGOs, the specific (areal) capacitance can be improved from 91.84 F·g−1 (19.74 mF/cm2) to 162.68 F·g−1 (29.16 mF/cm2), respectively, with 20 s APPJ processing time, as evaluated by cyclic voltammetry under a potential scan rate of 2 mV·s−1. The nitrogen DC-pulse APPJ is demonstrated to be an ultrafast and highly economical tool for efficiently processing nanocomposite electrodes of supercapacitors.

Scan-Mode Atmospheric-Pressure Plasma Jet Processed Reduced Graphene Oxides for Quasi-Solid-State Gel-Electrolyte Supercapacitors

A scanning atmospheric-pressure plasma jet (APPJ) is essential for high-throughput large-area and roll-to-roll processes. In this study, we evaluate scan-mode APPJ for processing reduced graphene oxides (rGOs) that are used as the electrodes of quasi-solid-state gel-electrolyte supercapacitors. rGO nanoflakes are mixed with ethyl cellulose (EC) and terpineol to form pastes for screen-printing. After screen-printing the pastes on carbon cloth, a DC-pulse nitrogen APPJ is used to process the pastes in the scan mode. The maximal temperature attained is ~550 °C with a thermal influence duration of ~10 s per scan. The pastes are scanned by APPJ for 0, 1, 3 and 5 times. X-ray photoelectron spectroscopy (XPS) indicates the reduction of C-O binding content as the number of scan increases, suggesting the oxidation/decomposition of EC. The areal capacitance increases and then decreases as the number of scan increases; the best achieved areal capacitance is 15.93 mF/cm2 with one APPJ scan, in comparison to 4.38 mF/cm2 without APPJ processing. The capacitance retention rate of the supercapacitor with the best performance is ~93% after a 1000-cycle cyclic voltammetry (CV) test. The optimal number of APPJ scans should enable the proper removal of inactive EC and improved wettability while minimizing the damage caused to rGOs by nitrogen APPJ processing.

Atmospheric-pressure plasma jet processed Pt/ZnO composites and its application as counter-electrodes for dye-sensitized solar cells

Nitrogen dc-pulse atmospheric pressure plasma jet (APPJ) is used to fabricate Pt/ZnO composites as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Due to the synergetic effect of the reactive plasma species and heat in nitrogen APPJ, the spin-coated precursors including chloroplatinic acid and zinc acetate can be reduced on fluorine-doped tin oxide (FTO) glass substrates in a few seconds. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analyses indicate that the precursors are reduced to Pt/ZnO under APPJ calcination. Electrochemical impedance spectroscopy (EIS) and Tafel measurement show the promising catalytic activities of Pt/ZnO CEs with low charge transfer resistance and high exchange current density. The efficiency of a DSSC with a 30-s APPJ-calcined Pt/ZnO CE is similar to that with a conventional furnace-annealed Pt CE for 15 min. The results indicate that nitrogen dc-pulse APPJ treatment is an efficient tool for rapidly fabricating Pt/ZnO composite CEs of DSSCs.

Improved performance of polyaniline/reduced-graphene-oxide supercapacitor using atmospheric-pressure-plasma-jet surface treatment of carbon cloth

This study evaluates carbon cloth treated using dc-pulse nitrogen atmospheric pressure plasma jet (APPJ) for a polyvinyl alcohol (PVA)/sulfuric acid (H2SO4) gel-electrolyte supercapacitor with a polyaniline (PANI)/reduced graphene oxide (rGO) nanocomposite electrode materials. The water contact angle of the carbon cloth decreases from 144.71° to 0° after the scanning APPJ surface treatment. The improved wettability can facilitate the penetration of the electrolyte into the porous electrodes, thereby improving the capacitance. X-ray photoelectron spectroscopy (XPS) indicates the introduction of nitrogen doping into to the carbon fibers of carbon cloth through the nitrogen APPJ treatment. Without APPJ treatment of carbon cloth, the specific (areal) capacitance of the fabricated supercapacitor is 315.0 F g−1 (55.67 mF/cm2); it increases to 580.2 F g−1 (106.89 mF/cm2) with APPJ surface treatment of carbon cloth before screen-printing the PANI/rGO nanocomposite. Electrochemical impedance spectroscopy (EIS) indicates a decreasing charge-transfer impedance at the electrode/electrolyte interface for supercapacitors with APPJ treatment of carbon cloth. This also improves the supercapacitive performance. After 1000-cycle cyclic voltammetry stability test, the capacitance retention rate is ∼85%. Our experimental results suggest that nitrogen dc-pulse APPJ in scanning mode is an efficient tool for enhancing the supercapacitance performance of a PANI/rGO supercapacitor.

Application of atmospheric-pressure plasma jet processed carbon nanotubes to liquid and quasi-solid-state gel electrolyte supercapacitors

We use a dc-pulse nitrogen atmospheric-pressure plasma jet (APPJ) to calcine carbon nanotubes (CNTs) pastes that are screen-printed on carbon cloth. 30-s APPJ treatment can efficiently oxidize and vaporize the organic binders, thereby forming porous structures. As indicated by X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA), the oxygen content decreases after APPJ treatment owing to the oxidation and vaporization of ethyl cellulose, terpineol, and ethanol. Nitrogen doping was introduced to the materials by the nitrogen APPJ. APPJ-calcination improves the wettability of the CNTs printed on carbon cloth, as evidenced by water contact angle measurement. Raman spectroscopy indicates that reactive species of nitrogen APPJ react violently with CNTs in only 30-s APPJ processing time and introduce defects and/or surface functional groups on CNTs. Carbon cloths with calcined CNT layers are used as electrodes for liquid and quasi-solid-state electrolyte supercapacitors. Under a cyclic voltammetry test with a 2mV/s potential scan rate, the specific capacitance is 73.84F/g (areal capacitance=5.89 mF/cm2) with a 2M KCl electrolyte and 66.47F/g (areal capacitance=6.10 mF/cm2) with a H2SO4/polyvinyl alcohol (PVA) gel electrolyte.

Flexible quasi-solid-state SnO2/CNT supercapacitor processed by a dc-pulse nitrogen atmospheric-pressure plasma jet

This study investigates flexible quasi-solid-state SnO2/CNT nanocomposite supercapacitors fabricated using a dc-pulse nitrogen atmospheric-pressure plasma jet (APPJ). The optimal APPJ processing time is merely 15s. Cyclic voltammetry (potential scan rate=2mV/s) shows an areal capacitance of 3.86mF/cm2 when flat and 4.42mF/cm2 under bending (bending radius R=0.55cm), indicating good functionality under flexing. The capacitance retention rate is 98.3% as evaluated after a 1000-cycle cyclic voltammetry test under bending (R=0.55cm), suggesting good operational stability.

A Comparison Study of Furnace and Atmospheric-Pressure-Plasma Jet Calcined Pt-Decorated Reduced Graphene Oxides for Dye-Sensitized Solar Cell Application

We performed a comparative study of dye-sensitized solar cells (DSSCs) with screen-printed Pt-decorated reduced graphene oxides (Pt/rGOs) processed by furnace- and atmospheric-pressure-plasma jet (APPJ)-calcination (substrate temperature = 510°C). A nitrogen APPJ interacts vigorously with carbonaceous materials in the pastes to enhance DSSC efficiency with a shorter processing time. However, prolonged APPJ-calcination can damage/oxidize rGOs; therefore, for longer processing times, furnace-calcination in turn achieves better DSSC performance. These results agree well with those of electrochemical impedance spectroscopy (EIS) and Tafel experiments.