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In this study, zinc sulphide nanomaterial (ZnS NM) powders were prepared with the assistance of an atmospheric pressure soft jet plasma (APPJ) device. Regular approaches to ZnS preparation mainly resulted in aggregated powders, thus plasma methods were investigated to obtain controlled morphological structures. The APPJ plasma-assisted ZnS exhibited unique surface architectures, such as nanorods, layers and spherical aggregates, that were controllably obtained by changing the reactant concentration and type of precursor. The prepared ZnS showed good thermal stability by no changes in its composition up to 400 °C. The APPJ plasma-assisted ZnS showed sphalerite and wurtzite crystal structures and resulted in excellent chemical purity. The simple and handy APPJ plasma method shows good potential for shape-controlled ZnS NMs preparation without addition of surfactant chemicals, mechanical stirring, external heating or any other tedious procedures. This capability showcases the scientific and technological merit of this technique. The prepared ZnS NMs were utilized as antibacterial agents and evaluated the activity using three techniques against the human pathogens of E. coli, S. aureus and K. pneumoniae. The ZnS NMs showed effective concentration and shape-dependent activity when used as an antibacterial material.

This research dealt with the preparation and characterization of silver oxide (SLO) nanomaterials (NMs) and their composite catalysts (i.e., silver and ruthenium oxide (SLORUO)). The prepared materials were tested for their catalytic performance in carbon monoxide (CO) oxidation. Generally, silver in its pure state is not widely used for CO oxidation due to stability and structural issues. However, the usage of subsurface oxygen and oxygen-induced reconstruction could be effective as an oxidation catalyst at a slightly high temperature. The low-temperature reaction of highly active RuO2 (RUO) is a well-known phenomenon. Thus, the possibility of using it with SLO to observe the combined catalytic behavior was investigated. The wet chemically prepared SLO and SLORUO NMs exhibited spherical and rods in spherical aggregate-type surface morphology belonging to cubic and rutile crystalline structures, respectively. The NMs and catalysts (i.e., the NMs on &gamma, Al2O3 catalyst support at 0.5 and 1.0 wt.% ranges) showed good thermal stability. The dry and wet CO oxidation using RUO and SLO showed concentration-dependent catalytic activity. The RUO, SLO, and SLORUO composites using 0.5 wt.% showed full CO oxidation at 200, 300, and 225 &deg, C, respectively. The reasons for the observed activity of the catalysts are explained based on the pore characteristics, chemical composition, and dispersion using H2 temperature-programmed reduction (TPR) behaviors.

In this study, a gate dielectric suitable for application in field effect transistors (FETs) was synthesized. Gate dielectrics were deposited using cyclohexane via plasma-enhanced chemical vapor deposition. These films were synthesized on silicon wafers substrates with plasma powers adjusted from 10 to 60 W. Graphene was synthesized on a nickel substrate by a thermal chemical vapor deposition process and coupled to the plasma-polymer via water transfer. Alpha step, Fourier-transform infrared spectroscopy, Raman spectroscopy, and atomic force microscopy findings in addition to water contact angle measurements were analyzed to characterize the physical and chemical properties of the plasma-polymer thin film. Furthermore, a probe station was used to characterize the FET devices fabricated using such films.

In the present investigation, plasma-polymerized ethyl cyclohexane (ECH) coatings were deposited onto AZ31 and AM50 magnesium (Mg) alloys using plasma-enhanced chemical vapor deposition. The influences of deposition time on the coating formation, surface morphology, chemical composition and electrochemical corrosion behavior were investigated. The coating deposition was confirmed by infrared spectroscopy (FT-IR), and the thickness was measured using a scanning electron microscope. Energy-dispersive x-ray analysis revealed an increase in carbon and a decrease in Mg concentrations as the coating duration was increased. Electrochemical impedance spectroscopy (EIS) results confirmed an improvement in the corrosion resistance of AZ31 and AM50 alloys due to ECH coatings in the presence of a 3.5 wt.% NaCl solution. Further, equivalent circuit curve fitting analysis of the EIS results indicated an increase in charge transfer resistance (Rct) values with longer coating durations. These results confirmed the protecting ability of ECH coatings against corrosive ion attack, which was also substantiated by the surface morphologies after corrosion. Impedance values decreased as the duration of exposure in a NaCl solution increased, and the coating prepared using a 30-min ECH deposition exhibited better protection properties.

Cadmium selenide (CdSe) semiconductor nanorods are prepared in hydrothermal process using hydrazine hydrate (N2H4.H2O) and ammonia (NH3.H2O) as reducing agents. The reaction time is increased to 7 h and the amount of hydrazine hydrate used is also increased to 15 mL which have resulted in diminished stacking faults in the CdSe nanorods prepared. The crystal structure, morphological variations, and size of the prepared CdSe nanorods are examined by XRD analysis. The crystalline size of the CdSe nanorods is 20–30 nm in diameter. HRTEM images reveal the formation of high order CdSe nanorods of the length about 25–40 nm. The bandgap in the CdSe nanoparticles is determined to be 2.17 eV. The peak at 595 nm in photoluminescence (PL) spectrum indicates oxygen vacancy defects in the prepared CdSe sample. The variation of dielectric properties with respect to temperature and frequency of pelletized CdSe is studied. High photocatalytic efficiency (98%) of catalyst/H2O2 is also achieved for decomposition of Rhodamine-B dye.

This manuscript discusses about size and shape-selective preparation of Zinc oxide nanomaterials (ZnO NMs) using simple and handy soft jet plasma source. The soft jet was operated in an atmospheric pressure with low energy consumption and utilized ambient air as a feed gas. The plasma synthesized ZnO NMs exhibited variety of surface morphology such as nanorods, nanosheets and micro-size flowers as compared to the conventional low temperature synthesized powders which showed spherical shape. The precursor concentrations and kinds of precursors were strongly influenced into the NMs morphology and possible growth mechanism in the presence of plasma has been proposed. It is suggested here that the soft jet plasma is an effective tool to control size and shape of ZnO NMs especially when the preparations demanding low temperature, surfactant free and cost-effective synthesis. The prepared ZnO NMs were tested for its shape dependent anti-bacterial property against Gram-positive bacteria namely S. iniae and S. parauberis and two Gram-negative bacteria such as E. coli and V. anguillarum . The flower-like ZnO NMs showed more powerful anti-bacterial activity than rod or sheet-like ZnO structures.

This study investigated on the effects of gate dielectrics for field effect transistors (FETs). The gate dielectrics with organic and inorganic layers were deposited on Si (100) substrates using cyclohexane and tetraethyl orthosilicate (TEOS) by plasma enhanced chemical vapor deposition (PECVD) method. After the Si (100) substrates were dry-cleaned by in situ Ar plasma bombardment with 60 W for 15 min., the gate dielectric plasma polymer thin films deposited under plasma power between 20 W and 60 W with different precursor flow ratio. Also, the active graphene layer was grown on a Ni substrate using CH4 by low-pressure thermal chemical vapor deposition (CVD) method, and the Ni substrate was then etched away. In order to fabricate a back-gate graphene-based FET, the graphene layer was adsorbed onto the plasma-polymer gate dielectric film, then 80 nm thick Au electrodes were finally evaporated onto the graphene using a mask with a gap of 370 nm, and a probe-station system was utilized to characterize the devices. As the plasma power and flow rate of TEOS increases, the gate voltage moves at a positive voltage, indicting p-doping by high fragmented Si and O elements under high plasma power and TEOS flow rate.

Present study deals with the preparation of differently shaped copper oxide nanomaterials (CuO NMs) using simple, reproducible wet chemical and hydrothermal approach. The influence of polyethylene glycol on the morphological control was also studied. The prepared nanomaterials exhibited new types of surface morphologies such as rice grain-like, needle-like and plate-like. The Fourier transform infrared spectra and the X-ray photoelectron spectra of all the samples showed identical chemical functional groups and did not exhibit the presence of any impurities. They exhibited good stability in the aqueous environment with the zeta potential values between −25 and −27 mV. The shape dependent anti-bacterial property of the prepared CuO NMs was evaluated against two Gram-positive bacteria namely Streptococcus iniae and Streptococcus parauberis and two Gram-negative bacteria such as Escherichia coli and Vibrio anguillarum . Among three CuO NMs, the plate-like CuO NMs displayed more powerful antibacterial activity than grain or needle shaped CuO NMs.

We investigate the electrical transport properties of multilayer graphene (MLG) following irradiation with Ar plasma. The plasma induces defects, including vacancies, voids, and nanoholes, which altered the resistance of the MLG. The resulting defect-rich MLG device exhibits an asymmetric ambipolar behavior, with a strong p-doping effect, which considerably deteriorates the electron conductivity, implies defect generation on the MLG surface. The pristine MLG was metallic; however, the resulting defect-rich MLG following plasma treatment exhibited a semiconductor-like temperature dependence of the resistance. Thus, MLG with morphological disorder exhibits a metallic-to-semiconductor transition in the resistance as a function of temperature.

This study deals with the preparation of SiO2, CuO and RuO2 nanomaterials and RuO2 based nanocomposites using dielectric barrier discharge (DBD) plasma. On account of an increasing attention toward the preparation of one dimensional nanostructure in recent days, the possibility to tune the morphology of the above materials by using plasma was investigated. The prepared nanomaterials were characterized by using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction spectroscopy and particle size analysis. Spherical, cylindrical and nanorod structures were observed for SiO2, CuO and RuO2, respectively. The morphology and the chemical composition of the RuO2/SiO2 and RuO2/CuO nanocomposites were analyzed using high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. It was noted that interaction of plasma species with each material differs from one another, and thus the materials exhibit different surface morphology. The reason might be the material's physico-chemical properties and in particular, depending on whether they belong to insulator or semiconductor.

This study deals with the observed changes in the structure and performance of polyethersulfone (PES) membranes due to in situ formation and ex situ addition of silica particles (SiO2). Hydrolysis and condensation of tetraethyl orthosilicate (TEOS) inside the PES polymer matrix and the reaction of TEOS with ammonium hydroxide were chosen to form in situ and ex situ SiO2 formations, respectively. The resultant structure confirmed by X-ray diffraction for the composite PES membranes showed the retention of the amorphous nature even after the addition of SiO2. The FTIR study revealed the functional groups corresponding to silica networks with enhanced OH signatures on the surface of the composite membranes. Field emission scanning electron microscopic images showed the variation in the surface and cross-sectional structures for the pure and composite membranes. Considerable reduction in the thickness of the skin, difference in the pore structure and ‘finger-like’ cross-sectional morphology with the presence of SiO2 was observed in PES membranes. Both SiO2/PES composite membranes were showed a minor change in their glass transition temperature (T g). The ex situ methodically formed composite membrane displayed an increase in the pure water flux and decrease in bovine serum albumin rejection as compared to in situ and pure PES membranes. These kinds of composite membranes can be utilized for water treatment applications demanding higher water flux.

A device consisting of a few layers of graphene (FLG) sheets was exposed to atmospheric plasma, resulting in the generation of significant number of defects, oxygen absorption, and doping. The plasma-induced electrical transformation and photoconducting properties of pristine FLG and plasma-irradiated FLG (p-FLG) were compared under visible and ultraviolet (UV) light illumination. The visible light photoresponsivity of p-FLG was 0.47 AW−1 at 535 nm, comparatively higher than that observed for pristine FLG (10 m AW−1); this result was attributed to the formation of defect midgap states band by plasma irradiation. Photoinduced molecular desorption causes the responsivity of the higher energy (UV) photons. Our results suggest that plasma irradiation is a simple, novel way to tailor the optoelectronic properties of graphene layers.

This article reports the modification of polyethersulfone (PES) membrane using silver nanoparticles (n-Ag), their characterizations and protein separation performances. As a bio-mediated synthesis route, gram-positive Bacillus subtilis bacterial supernatants were employed for preparing n-Ag. The resulting n-Ag exhibited uniform and well defined spherical morphology with size less than 50nm. The effect of the incorporation of n-Ag on PES membrane in terms of cross sectional morphology, surface roughness, crystallinity and hydrophilicity were investigated systematically. XPS analysis showed that a significant portion of silver was in silver oxide form. Depth profiling by argon plasma etching and XPS showed the partition of Ag2O and Ag between the membrane surface and the bulk. A minor oxidation on the surface of the silver was observed whereas the internal structure of the membrane retained Ag in its metallic state. The potential of the nano composite membrane for the separation of BSA with varying feed concentration and transmembrane pressure were performed. At 1.5wt% loading of n-Ag in neat PES, enhancement in bovine serum albumin (BSA) flux and decrease in the rejection were observed. The results and performance of the PES/n-Ag nanocomposite membranes indicate that it would be a deserving candidate for future industrial separations. The experimental results confirm that the incorporation of Ag nanoparticles in PES UF membrane can increase hydrophilicity and reduce the fouling.

This work reports the potential of atmospheric pressure dielectric barrier discharge (DBD) plasma for synthesizing Ruthenium dioxide (RuO2) nanomaterials with various morphologies. The RuO2 nanomaterials were grown on four kinds of substrates including copper, silicon, glass and polyethylene terephthalate. The feed gas to the DBD plasma reactor was Ar or Ar + O2 mixture, which creates an inert or oxidation atmosphere, respectively. The prepared nanomaterials were characterized by using X-ray diffraction spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The morphology of the RuO2 nanomaterials prepared by exposing the precursor to the DBD plasma was found to depend strongly on the characteristics of the substrate as well as on the composition of the feed gas. Spherical and sheet shaped nanomaterials prepared using the above technique was analyzed for their size dependent photocatalytic behavior in the presence of visible light. Methylene blue degradation was found mainly dependent on the nanomaterial concentration and at the same time sheet shaped nanomaterials showed more catalytic activity as compared to spherical shaped RuO2.

The original version of this article unfortunately contains a mistake. Two numbers in the acknowledgement section are incorrect. The correct acknowledgements are as follows

Spherical and sheet-like Ruthenium oxide (RuO2) nanomaterials were prepared by wet chemical approach. A new kind of sheet-like morphological features in RuO2 (with length and width >1 μm and 250 nm, respectively) was obtained by using polyethylene glycol (PEG) surfactant. The physical and chemical characterization for the synthesized RuO2 nanomaterials were carried out with the help of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The prepared nanomaterials were assessed for the shape dependent anti-microbial activities against fish pathogenic bacteria such as Vibrio anguillarum, Edwardsiella tarda, Streptococcus iniae and Streptococcus parauberis. Energy dispersive X-ray spectroscopy (EDS mapping) displayed the adsorption of nanomaterials on the bacterial surface. Both types of nanomaterials exhibited higher antibacterial activity against Gram-negative bacteria and in particular, sheet-like RuO2 nanomaterials showed more inhibitive effect than spherical types.

This work investigated the decomposition of ethylene in a continuous flow dielectric-packed bed plasma reactor filled with various packing materials at atmospheric pressure and room temperature. When compared to the case without any packing material, the reactor filled with packing materials remarkably facilitated the plasma-induced decomposition of ethylene in the order of a-alumina > silica > zirconia > glass wool (GW). Under identical condition, the increase in the decomposition efficiency (DE) with increasing the specific energy input was more rapid in the plasma reactor filled with the packing materials than in the blank plasma reactor. In the early stage, almost complete decomposition of ethylene was observed with the a-alumina, but after a certain period of time, the DE decreased with time. Unlike theaalumina, the other packing materials examined did not show any significant deterioration in the decomposition over time during 10-h operation. After the regeneration of the used packing materials by using the plasma in the presence of oxygen, the original decomposition performance was nearly recovered. The decrease in the BET surface area due to the formation of polymer deposits was observed in the used aalumina and silica; however the surface area was almost regained by the regeneration. While no other byproducts except carbon oxides and N2O were detected with the a-alumina and silica, methane, acetylene, formaldehyde and N2O were identified in the effluent gas with the zirconia and GW packing materials.

Kapton® [poly (4,4′-oxy diphenylene pyromellitimide)] polyimides have widespread usage in semiconductor devices, solar arrays, protective coatings and space applications, due to their excellent chemical and physical properties. In addition to their inherent properties, imparting superhydrophobicity on these surfaces will be an added advantage. Present work describes the usage of Ar + O2 plasma treatment for the preparation of superhydrophobic Kapton® surfaces. Immediately after the plasma treatment, the surfaces showed superhydrophilicity as a result of high energy dangling bonds and polar group concentration. But the samples kept in low vacuum for 48 h exhibited superhydrophobicity with high water contact angles (>150°). It is found that the post plasma treatment process, called ageing, especially in low vacuum plays an important role in delivering superhydrophobic property to Kapton®. Field emission scanning electron microscopy and atomic force microscopy were used to probe the physical changes in the surface of the Kapton®. The surfaces showed formation of nano-feathers and nano-tussock microstructures with variation in surface roughness against plasma treatment time. A thorough chemical investigation was performed using Fourier transform infrared spectroscopy and micro-Raman spectroscopy, which revealed changes in the surface of the Ar + O2 plasma treated Kapton®. Surface chemical species of Kapton® were confirmed again by X-ray photoelectron spectroscopy spectra for untreated surfaces whereas Ar + O2 plasma treated samples showed the de-bonding and re-organization of structural elements. Creation of surface roughness plays a dominant role in the contribution of superhydrophobicity to Kapton® apart from the surface modifications due to Ar + O2 plasma treatment and ageing in low vacuum.

The performances of the porous and nonporous α-alumina (α-Al2O3) for the decomposition of ethylene in a dielectric-packed bed plasma reactor were comparatively examined with respect to the decomposition efficiency and the formation of byproducts. The decomposition was mainly controlled by discharge power, oxygen content, and properties of the alumina, such as porosity and surface area. The addition of a small quantity of oxygen led to an increase in the generation of oxidative species which eventually increased the ethylene decomposition efficiency. In the presence of 5 % oxygen, ethylene at an initial concentration of 1,898 ppm was completely oxidized into CO or CO2 when using the porous α-alumina. On the other hand, the nonporous α-alumina resulted in an incomplete oxidation, producing several carbon-containing byproducts other than CO and CO2. Moreover, with the other conditions kept constant, the decomposition efficiency obtained with the porous α-alumina was higher than that with the nonporous one, suggesting the adsorption capability of the packing material plays an important role in the decomposition process.

Silver oxide, ruthenium oxide nanomaterials and its composites are widely used in a variety of applications. Plasma-mediated synthesis is one of the emerging technologies to prepare nanomaterials with desired physicochemical properties. In this study, dielectric barrier discharge (DBD) plasma was used to synthesize Ag2O and Ag2O/RuO2 nanocomposite materials. The prepared materials showed good crystallinity. The surface morphology of the Ag2O exhibited “garland-like” features, and it changed to “flower-like” and “leaf-like” at different NaOH concentrations. The Ag2O/RuO2 composite showed mixed structures of aggregated Ag2O and sheet-like RuO2. Mechanisms governing the material’s growth under atmospheric pressure plasma were proposed. Chemical analysis was performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) showed the thermal decomposition behavior and the oxygen release pattern.

The effect of inorganic and organic additives in polyethersulfone (PES) membranes was investigated for the possible enhancement in ultrafiltration performances. Tetraethylorthosilicate (TEOS) and polyethyleneimine (PEI) were chosen as inorganic respective silica precursor and organic additive based on their potential to promote hydrophilicity in PES membranes. With the addition of TEOS and PEI in PES casting solution, the viscosity and hydrophilicity were increased.In addition of TEOS in PES, the SiO 2 particles were homogeneously dispersed in PES matrix, a large amount of OH groups on the SiO 2 particles generated, and led to an improvement in the hydrophilic property. Characterizations of membranes by FTIR and X-ray Diffraction (XRD) confirmed that the PES suffered a transform from various functional groups due to the addition of TEOS. The 40% of water permeability was found by 5% addition ion of TEOS and PEI repressively. The top surface and cross-section morphology of PES membranes changed from dense-like structure to finger-like macrovoids structure with increasing TEOS and PEI content. Protein solution separation was investigated using lysozyme and bovine serum albumin (BSA) with the concentration of 1000 ppm. The observed sieving coefficient of protein decreased exponentially with increasing contents of TEOS and PEI in PES membranes.

Ar + H2 plasma cleaning has been described for the surface modification of the steel substrates, which removes oxides and other contaminants from substrate surface effectively leading to a better adhesion of the physical vapor deposited (PVD) coatings. Approximately 1.1–1.3 μm thick TiAlN coatings were deposited on plasma treated (Ar and Ar + H2) and untreated mild steel (MS) substrates. A mechanism has been put forward to explain the effect of plasma treatment on the substrate surface based upon the data obtained from X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The XPS measurements on untreated and Ar + H2 plasma etched MS substrates indicated that the untreated substrate surface mainly consisted of Fe3O4, whereas, after etching the concentration of oxides decreased considerably. The FESEM and the AFM results showed changes in the surface morphology and an increase in the substrate roughness as a result of Ar + H2 plasma etching. Removal of oxide/contaminants, formation of coarser surface and increased substrate surface roughness as a result of Ar + H2 plasma etching facilitate good mechanical interlocking at the substrate surface, leading to a better adhesion of the deposited PVD coatings. The adhesion of TiAlN coating could be increased further by incorporating a very thin Ti interlayer.

Silver oxide, ruthenium oxide nanomaterials and its composites are widely used in a variety of applications. Plasma-mediated synthesis is one of the emerging technologies to prepare nanomaterials with desired physicochemical properties. In this study, dielectric barrier discharge (DBD) plasma was used to synthesize Ag2O and Ag2O/RuO2 nanocomposite materials. The prepared materials showed good crystallinity. The surface morphology of the Ag2O exhibited “garland-like” features, and it changed to “flower-like” and “leaf-like” at different NaOH concentrations. The Ag2O/RuO2 composite showed mixed structures of aggregated Ag2O and sheet-like RuO2. Mechanisms governing the material’s growth under atmospheric pressure plasma were proposed. Chemical analysis was performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) showed the thermal decomposition behavior and the oxygen release pattern.

Plasma Applications Laboratory, Department of Chemical and Biological Engineering, Jeju National University, Jeju 690 756,Republic of KoreaThe authors of the abovepaper would like to point out that therewas an error in the ‘Acknowledgements’section. The projectnumber, ‘(2013R1A1A2064471)’, should instead be ‘(2013R1A2A2A01068926)’.

One-dimensional (1D) nanostructured materials have attracted a great deal of interest owing to their potential applications in various industries. Due to the limitations and cost associated with conventional low-pressure plasma systems, atmospheric-pressure plasma techniques such as dielectric barrier discharges (DBDs) are investigated as an alternative approach for inducing specific chemical reactions. RuO2 nanomaterials are widely used as supercapacitor electrodes, in field-emission devices and for catalytic applications. In such applications, size and shape dependent properties of nanomaterials play critical roles in improving the performance. In this paper, an attempt is made to prepare 1D RuO2 nanostructured materials using a DBD plasma. It is reported here that the composition of feed gas is an important factor in determining the final morphology. For example, an Ar + H2 plasma yields aggregated RuO2 nanostructures, whereas 'nanopillar' and 'nanorod' morphologies are obtained when using Ar + O2 and Ar, respectively. Possible mechanisms behind the morphological differences are elucidated on the basis of the temperature variations inside the plasma reactor and the chemistry of the gaseous reactive species. The application of a DBD plasma to the synthesis of RuO2 nanorods is reported for the first time in this paper.