Liquid Phase Plasma Research Articles

Synthesis Process of Copper/Graphene Nanocomposite by the Liquid Phase Plasma Reduction Method.

Liquid phase plasma (LPP) process was applied to the impregnation of copper nanoparticles onto graphene sheet. Approximately 30-50 nm sized tetragonal nanoparticles were dispersed uniformly on the surface of the two-dimensional graphene sheet. The amount of copper nanoparticles precipitated increased with increasing LPP process time. When combined with a subsequent process, the synthesized copper/graphene nanocomposites will be able to high-performance Li-ion batteries effectively.

Application Of Liquid Phase Plasma Process To The Synthesize Ruthenium Oxide/activated Carbon composite As Dielectric Material For Supercapacitor

The ruthenium oxide/activated carbon composite (RCC) were synthesized using an innovative plasma-in-liquid process, which is known as liquid phase plasma (LPP) process. This technique uses a single-step process for the synthesis of metal nanoparticles on supporting materials. LPP process led to simultaneous precipitation of ruthenium and ruthenium oxide nanoparticles on the surface of activated carbon, which is then oxidized to ruthenium oxide during the thermal oxidation process. The specific capacitances of RCC electrodes prepared through the LPP and oxidation process were higher than that of bare AC. The specific capacitance increased with increasing LPP process duration and oxidation treatment. The specific capacitance of ruthenium oxide/carbon composite increased with increasing LPP process duration. The ruthenium oxide/carbon composite prepared through the LPP process and thermal oxidation showed smaller resistances and larger initial resistance slopes than bare activated carbon powder and this effect was intensified by increasing the LPP process duration. The RCC electrodes showed smaller resistances and larger initial resistance slopes than bare AC and this effect was intensified by increasing the LPP process duration and oxidation treatment. Copyright © 2016 VBRI Press.

Electrochemical properties of LiNi1/3Co1/3Mn1/3O2 electrodes prepared with water-based slurry dispersed conducting additive by using liquid-phase plasma treatment

LiCo1/3Ni1/3Mn1/3O2 cathode electrodes were prepared using the doctor blade technique, where distilled water was used instead of ordinary NMP as the solvent. A serious problem is caused because the dispersion of hydrophobic carbon particles used as a conducting additive is difficult in water solvent. In this study, as a novel technique for the carbon particle dispersion, low-temperature liquid-phase plasma treatment was applied. The surface of carbon particle was converted from hydrophobic to hydrophilic via OH radical formation. The treatment enabled us to obtain stable colloidal dispersion of the carbon particles. The film electrode with smooth surface and no aggregates was easily attained. The electrode prepared using the water-based slurry has superior cycling performance and slightly-poorer rate capability compared to that of the electrodes prepared using the NMP-based slurry.

ソリューションプラズマ－スパッタ法を用いた金ナノ粒子合成速度に与える溶媒組成の影響

For this study, we applied a specific type of plasma in liquid phase named “solution plasma process（SPP）” for high-speed synthesis of gold nanoparticles（AuNPs）using an ethanol-water mixture as a liquid medium. Sputtering was conducted for the AuNP production. By applying high voltage across a pair of gold electrodes（∅＝1.0 mm）immersed in the liquid medium, ions formed in the plasma collided with the gold electrode surface and caused sputtering of the gold atoms. Subsequently, these atoms formed AuNPs immediately before dispersal into the medium. We inferred that the medium properties greatly influenced the SPP system sputtering mechanism. Accordingly, the influence of the ethanol-water mixture composition on the formation mechanism was studied in addition to the yield of the synthesized AuNPs. Results indicate that composition of the ethanol-water mixtures strongly influenced the breakdown conditions for the plasma formation and that the largest current observed at the ethanol mole fraction was 0.089-0.14. It is particularly interesting that this composition of the ethanol-water mixture led to the highest AuNPs formation yield. Our findings suggest that high-speed synthesis of metal nanoparticles in the SPP system is achievable by altering the type and/or composition of the liquid medium.

Titanium dioxide modification with cobalt oxide nanoparticles for photocatalysis

Liquid phase plasma (LPP) method was used to synthesize a photocatalyst that can respond to visible light by precipitating cobalt oxide nanoparticles on the surface of TiO2 powders. Uniform precipitation of cobalt oxide nanoparticles on the surface of TiO2 powders was observed, resulting in successful synthesis of Co oxide nanoparticles on TiO2 photocatalysts (CTP). The CTP synthesized in this study showed a photocatalytic activity under visible blue light. However, its photocatalytic activity was lower than that of bare TiO2 under UV light because the cobalt oxide precipitate acted as crystal defects deteriorating the catalytic activity.

Preparation and Characterization of Low Molecular Weight Heparin by Liquid Phase Plasma Method.

An liquid phase plasma process system was applied to the production of low molecular weight heparin. The molecular weight of produed heparin decreased with increasing liquid phase plasma treatment time. The abscission of the chemical bonds between the constituents of heparin by liquid phase plasma reaction did not alter the characteristics of heparin. Formation of any by-products due to side reaction was not observed. It is suggested that heparin was depolymerized by active oxygen radicals produced during the liquid phase plasma reaction.

Preparation of Aluminum Nanoparticles Using Bipolar Pulsed Electrical Discharge in Water

Al nanoparticles were synthesized in liquid phase plasma using Al chloride as the precursor. CTAB was used as the surfactant to obtain well dispersed particles. When the surfactant was not added, large aggregated particles were generated. With increasing CTAB dosage, the size of the Al particles decreased and the degree of dispersion of the particles increased. At the initial stage of plasma discharge, dendrite shaped particles were produced. As discharge time evolved, however, particle size decreased and the particle morphology also changed into spherical shape. The solution pH decreased with increasing plasma discharge time.

Effect of the surfactant on size of nickel nanoparticles generated by liquid-phase plasma method

The effect of anionic and cationic surfactants on the generation of nickel nanoparticles in a liquid-phase plasma was investigated. The size and morphology of nanoparticles generated under different conditions were observed. When no surfactant was added, more and larger particles were generated under a longer plasma treatment time and a higher electrical conductivity of the solution. When an anionic surfactant SDS was added, spherical nickel nanoparticles with various sizes were generated, with no clear evidence for the effect of SDS observed. When a cationic surfactant CTAB was added, very small nanoparticles (≤ 10 nm) could be obtained with a short reaction time. When the reaction time was too long (≥ 60 minutes), larger polygonal or wisker-shaped particles were generated.

Preparation and Characterization of Cobalt/Graphene Composites Using Liquid Phase Plasma System.

Liquid phase plasma (LPP) method was applied, for the first time, to the impregnation of cabalt nanoparticles onto graphene. Nanoparticles were dispersed uniformly on the surface of the two-dimensional graphene sheet. The electron miocroscopy observation showed approximately 2-7 nm sized spherical nanoparticles deposited on the surface of graphene sheets. The XPS and EDX analyses revealed that both metal Co and CoO were present in the Co/graphene composites synthesized by the LPP method.

Nano Carbon Black Powder Synthesized via Liquid Phase Plasma Process as a Supercapacitor Active Material

In this study, synthesized carbon black powder (SC) was obtained from benzene via a liquid phase plasma (LPP) process. This powder was then activated by KOH to obtain activated SC (A-SC). Both of SC and A-SC powders were compared with commercial carbon black powder (CCB) and activated commercial carbon black (A-CCB) via Brunauer–Emmett–Teller surface area analysis, Raman spectroscopy, scanning electron microscopy, and X-ray diffraction for physical and chemical investigations. SC, A-SC, CCB and A-CCB powders were used as active materials of electrochemical double-layer capacitors (EDLC), which were studied via cyclic voltammetry, galvanostatic measurements, and impedance spectroscopy. Their electrochemical performance shows that SC electrode has higher specific capacitance, capacity, and energy than CCB electrode. Non-aqueous electrolyte EDLC using A-SC electrode, especially exhibited suitable cyclic stability over 8000 cycles at various charge–discharge current densities from 250 mA g−1 to 2000 mA g−1. This study indicates that the LPP process successfully created specific nano-scaled CB particles supported by KOH activation process, which are noteworthy electrode materials for supercapacitor applications.

Investigation on Sized-Regulated Iron Nanoparticles Prepared by Liquid Phase Plasma Reduction Process

The liquid-phase plasma reduction method has been applied to prepare iron nanoparticles from iron chloride solution using a bipolar pulsed electrical discharge system. The excited states of atomic iron, hydrogen, and oxygen as well as the molecular bands of hydroxyl radicals were detected in the emission spectra. The iron nanoclusters formed at the initial stage convert to dispersion of small iron nanoparticles, which then grows slowly to form anisotropic, tetragonal shape. The cationic surfactant of CTAB was shown to exhibit a large influence on the particle generation procedure.

Synthesis of manganese oxide/activated carbon composites for supercapacitor application using a liquid phase plasma reduction system

Manganese oxide/carbon composite electrode was synthesized using liquid-phase plasma method, to be applied to supercapacitor. Spherical manganese oxide nanoparticles smaller than 10 nm were dispersed uniformly on the surface of YP-50F. The increase in the amount of manganese oxide precipitated on YP-50F resulted in improved specific capacitance, charge–discharge rate, and Warburg impedance but specific surface area and total pore volume were decreased.

Performance improvement of liquid phase plasma processed carbon blacks electrode in lithium ion battery applications

Cyclic stability of carbon blacks as an anode electrode in lithium ion batteries was studied using commercial (SP & KB) and synthesized (SC) ones. SC was processed by liquid phase plasma process. The cyclic stability was found to be affected with the presence of solid electrolyte interface(SEI). Unlike the commercial carbon blacks in which SEI formed at early stage of charge-discharge cycles, SC showed a gradual formation of SEI with the cycles. The SEI formation was confirmed by the trace of resistance changes with the impedance measurements. SP was observed to have the best charge-discharge cyclic stability. Meanwhile, the capacity of SC was gradually decreased with the cycle until the formation of SEI even though it had higher capacity than the commercial ones through the measurement cycles of up to 50. The cyclic stability of SC carbon blacks was greatly improved by mixing with SP with a slight sacrifice of capacity.

Synthesis of tin and tin oxide nanoparticles using liquid phase plasma in an aqueous solution

Liquid phase plasma method was applied to the synthesis of Sn nanoparticles. Tin chloride was used as the tin precursor. Dendrite-shaped particles were formed at the initial stage of the reaction, while spherical nanoparticles were generated at longer discharge time. When the discharge time was too long (longer than 50min in this study), anisotropic SnO2 nanoparticles were produced. With increasing dosage of Cetyltrimethylammonium bromide, used as the surfactant, the Sn particle size decreased, while the degree of dispersion of the particles increased. Higher electrical conductivity of the reactant solution resulted in the production of larger Sn nanoparticles. The solution pH decreased with increasing plasma discharge time until 50min, after which pH slightly increased, co-occurring with the formation of SnO2 nanoparticles.

Bipolar Pulsed Electrical Discharge for Synthesis of Tungsten Nanoparticles in the Aqueous Solutions

ABSTRACTThe liquid phase plasma reduction method was applied to prepare the tungsten nanoparticles from the solu-tion of tungsten chloride using bipolar pulsed electrical discharge system. The liquid phase plasma providesextremely rapid reactions caused by activated chemical species. The OH radicals produce H 2 O 2 and the hydro-gen radicals are used for the reduction process to generate W nanoparticles. While spherical tungsten nanopar-ticles were mostly observed, triangular and hexagonal-shaped nanoparticles were also observed occasionallyin the plasma treated reactant solution. The anionic surfactant of SDS was shown to exhibit a large in”uenceon the particle generation procedure.KEYWORDS: Tungsten, Nanoparticle, Liquid Phase Plasma, Surfactant, Emission Spectra. 1. INTRODUCTION Nanotechnology has gained a considerable importance,in the recent times. Tungsten nanoparticles are used asfunctional materials. 1 These particles exhibit peculiar ther-mal behavior that was thought to be associated with storedinternal energy.

The Effect of Liquid Phase Plasma for Photocatalytic Degradation of Bromothymol Blue

Advanced oxidative degradation of a textile dye derivative, bromothymol blue, has been investigated by liquid phase plasma process with titanium dioxide. A bipolar pulsed power supply was used to generate discharges in the aqueous solution. Properties of generated plasma were investigated by electrical and optical emission spectroscopy methods. The comparison of properties of the discharge operated with and without oxygen gas bubbling is shown. The results of electrical-discharge degradation of bromothymol blue showed that the decomposition rate increased with the applied voltage, pulse width, and frequency. While appropriate oxygen gas bubbling enhanced the decomposition efficiency, excessive bubbling deteriorated the decomposition efficiency by inhibiting the generation of plasma. The bromothymol blue decomposition rate was shown to increase with the TiO2 particle dosage.

Surface modification of magnesium alloy via cathodic plasma electrolysis and its influence on corrosion resistance and cytocompatibility

To improve corrosion resistance and enhance biocompatibility of magnesium alloy, cathodic plasma electrolysis (CPE), a liquid phase plasma technique, was used to fabricate zirconia (ZrO2) coatings onto WE43 magnesium alloy substrate. Surface morphology and phase composition of the coatings on magnesium alloy substrates were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The potentiodynamic polarization test in simulated body fluid (SBF) indicated that corrosion resistance of magnesium alloy was significantly improved by this CPE treatment. The results of cytocompatibility including osteoblasts adhesion and viability suggested that surface modification of magnesium alloy with ZrO2 coating fo’rmed via CPE technique is beneficial for cell proliferation and differentiation. The approach presented here should be an attractive way for surface modification of magnesium-based implants to improve anticorrosion and bone osseointegration.

Carbon black nanoparticles with a high reversible capacity synthesized by liquid phase plasma process

Carbon blacks synthesized by the liquid phase plasma process in benzene with and without distilled water showed a very high charging capacity of about 1,540–1,600 mAh/g depending on the liquid involved. CBs synthesized from organic benzene only were found to have a higher specific surface area compared to CBs from benzene with water, contributing to the higher charging capacity of 1,600 mAh/g. The charge–discharge cyclic stability (measured from 2 to 20 cycles) of the CBs synthesized from benzene was significantly improved with the addition of water from 58 % to about 70 % reversible capacity. Our results suggest a promising method of producing carbon black nanoparticles at low temperatures with a reasonable performance applicable for lithium ion batteries.

Contribution of Dissolved Oxygen to Methyl Orange Decomposition by Liquid Phase Plasma Processes System

Degradation of methyl orange (MO) in liquid phase plasma (LPP) was investigated. A bipolar pulsed power supply was used to generate discharges in the aqueous solution. Properties of generated plasma were investigated by electrical and optical emission spectroscopy methods. The MO decomposition rate increased with increasing levels of applied voltage, pulse width and frequency. The concentrations of activated species, including OH• radicals, were increased by the supply of DO. The concentration of OH• increased with increasing DO concentration up to 50 ppm. Further increase in the DO concentration, however, reduced the OH• concentration because of recombination of OH• radicals. The trend of MO decomposition rate with varying DO concentration was the same as that observed for the OH• concentration, suggesting that OH• radicals play a critical role in the decomposition of MO. Therefore, the LPP process for MO decomposition should be operated with an optimum DO concentration where the OH• radical concentration becomes highest.

Liquid phase plasma treatment for improved detachment of pigmented inkjet printed paper

A new method of improving deinking of flexographic and inkjet printed paper has been investigated. It was found that the liquid plasma treatment method was able to improve the ink elimination and luminosity without negatively impacting the color a* or ink elimination of the recycled paper. However, it was found that the filtrate darkening was increased by the liquid plasma treatment because the treatment was not able to increase the amount of ink removed through flotation. Because of this, the liquid plasma treatment is likely improving the deinkability parameters by improving the ink detachment of flexographic and inkjet inks.