In-Liquid Plasma Process for Size- and Shape-Controlled Synthesis of Silver Nanoparticles by Controlling Gas Bubbles in Water

Most methods controlling size and shape of metal nanoparticles are chemical methods, and little work has been done using only plasma methods. Size- and shape-controlled synthesis of silver nanoparticles (Ag NPs) is proposed based on adjusting the gas bubble formation produced between two silver electrodes. The application of a voltage waveform with three different pulse widths during a plasma process in water can generate different gas bubble formations. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of Ag NPs synthesized using three different bubble formations reveal that spherical Ag NPs are synthesized when very tiny bubbles are generated between two electrodes or when only the grounded electrode is enveloped with large gas bubbles, but Ag nanoplates are synthesized when both electrodes are completely enveloped with large gas bubbles

Preparation and synthesis of carbon nanomaterials from 1-hexanol by solution plasma process with Ar/O2 gas bubbles

This study presents the simple and catalyst-free methods for synthesizing carbon nanomaterials from 1-hexanol alcohol by using stable solution plasma process by varying the argon (Ar), oxygen (O2), and Ar and O2 mixtures plasma working gas bubble. The structural characteristics of carbon nanomaterials are measured by transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. The discharge characteristics are examined based on the discharge voltage, current, and optical emission spectrometer (OES) techniques. By using the external Ar gas bubble discharge during solution plasma process, the size of carbon nanoparticle and discharge voltage are decreased compared to the no gas case and the discharge current is increased, which would be due to the increase of plasma energy and enhancement of the square of plasma-liquid contact to plasma volume. By using the external O2 gas bubble discharge during solution plasma process, whereas, the size of carbon nanoparticle is increased compared to the no gas case and the discharge voltage and current are decreased, which would be due to the production of relatively high amounts of oxygen radicals, resulting in the flame synthesis. Raman spectra results show that the degree of graphitization of the carbon nanomaterials synthesized with external Ar 150 and O2 50 standard cubic centimeter per minutes (sccm) mixtures gas bubble during solution plasma process is observed to be greater than that of the carbon nanomaterials synthesized with the only Ar or O2 gas bubble. This solution plasma process by varying the plasma working gas mixtures can potentially be used for the precise nanomaterial synthesis. © 2019 Taylor & Francis Group, LLC.1

Simple one-step synthesis of carbon nanoparticles from aliphatic alcohols and n-hexane by stable solution plasma process

This paper examines a simple one-step and catalyst-free method for synthesizing carbon nanoparticles from aliphatic alcohols and n-hexane with linear molecule formations by using a stable solution plasma process with a bipolar pulse and an external resistor. When the external resistor is adopted, it is observed that the current spikes are dramatically decreased, which induced production of a more stable discharge. Six aliphatic linear alcohols (methanol-hexanol) containing carbon with oxygen sources are studied as possible precursors for the massive production of carbon nanoparticles. Additional study is also carried out with the use of n-hexane containing many carbons without an oxygen source in order to enhance the formation of carbon nanoparticles and to eliminate unwanted oxygen effects. The obtained carbon nanoparticles are characterized with field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results show that with increasing carbon ratios in alcohol content, the synthesis rate of carbon nanoparticles is increased, whereas the size of the carbon nanoparticles is decreased. Moreover, the degree of graphitization of the carbon nanoparticles synthesized from 1-hexanol and n-hexane with a high carbon (C)/oxygen (O) ratio and low or no oxygen is observed to be greater than that of the carbon nanoparticles synthesized from the corresponding materials with a low C/O ratio.1

Experimental study on atmospheric pressure plasma polymerized conducting polymer under coupling and remote conditions

This article has analyzed conducting polymer from the viewpoint of material properties, which is polymerized under atmospheric pressure condition for coupling and remote conditions, respectively. The experimental results show that the atmospheric pressure plasma polymerized pyrrole (pPPy) exhibits similar characteristics from the viewpoint of crystallinity, but the shapes and roughness of the particles are significantly distinguished. In the case of coupling condition, a uniform and flat layer like a thin film was obtained. However, in the case of remote condition, the deposited layer had more rough nanoparticles compared to that of coupling condition. The pPPy surface characteristic and morphology changes are discussed by using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) results. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis are used to determine the chemical changes introduced by the atmospheric pressure plasma for coupling and remote conditions. The both pPPy materials, which were obtained by coupling and remote conditions, are expected to be applied to various fields, especially for designing the thin conducting electrode layer of polymer light emitting diode (P-LED) or for improving the efficiency by inserting conducting polymer powder on hole injection layer. © 2018 Taylor & Francis Group, LLC.1

Synthesis of carbon materials by solution plasma reactor with stable discharge and advanced plasma spray deposition method

This work presents a deposition of carbon thin films on the substrate from sucrose-containing-carbon source, that is, sugar, by using the two different plasma processes; one process is that the carbon particles are obtained from the sugar in the stable solution plasma reactor with external resistor, and the other process is that the carbon thin films are deposited on the substrate from the carbon particles obtained from sugar by using the atmospheric pressure plasma (APP) spray method. The carbon particles are obtained at a bipolar pulse waveform with a peak value of 1.5 kV and a frequency of 5 kHz under solution plasma, whereas the carbon thin films are deposited at a sinusoidal pulse waveform with a peak value of 12.5 kV and a frequency of 33 kHz under the APP spray method. Voltage probe, discharge current, and optical emission spectrometer (OES) techniques are used to analyze the plasma produced from the solution plasma reactor. Field emission scanning electron microscopy (FE-SEM) and ultraviolet–visible (UV-vis) spectroscopy techniques are used to analyze the carbon particles. FE-SEM results show that carbon materials from sucrose have a few ten to hundred nanometer size nanoparticles characteristics. The UV-vis and OES analyses show the characteristic graphene peaks with evidence that carbon sources from sucrose are broken due to discharge energy. This study contributes to a better understanding on the new synthesis method of carbon materials from renewable resource with low-cost, i.e. sugar cane. © 2018 Taylor & Francis Group, LLC.1