Effect of radical on defect and molecular structure of monolayer MoS2 by low temperature plasma treatment

Author(s):  
Shuya ASADA ◽  
Akihisa OGINO

Abstract The aim of this study is to form the sulfur defects on monolayer molybdenum disulfide (MoS2) by low temperature microwave plasma treatment suppressing disturbance of molecular structure. CVD-grown and plasma treated multilayer MoS2 surface were analyzed to investigate the effects of H2 and Ar plasma treatment on sulfur defects and molecular structure. It was found that the disturbance of molecular structure was suppressed in the H2 plasma treatment compared to the Ar plasma treatment. Varying the incident ratio of hydrogen ions H+ and radicals H*, the influences of H2 plasma treatment with high and low H*/H+ ratio on monolayer MoS2 structure were discussed. As a result of X-ray photoelectron spectroscopy, Raman spectroscopy and photoluminescence analysis, sulfur defects increased with the increase in total amount of radical incident on MoS2. In addition, it is speculated that the etching with radical contributed to form sulfur defects suppressing the disturbance of molecular structure.

2019 ◽  
Vol 14 ◽  
pp. 155892501985402
Author(s):  
Ting Su ◽  
Ying Han ◽  
Hongyan Liu ◽  
Lixin Li ◽  
Zongcai Zhang ◽  
...  

Dyeability of the fiber plays a very important role in the textile industry. The presence of cuticle scales on the surface of Rex rabbit fibers brings difficulties to dyeing process. In this study, O2 low temperature plasma was used to improve the dyeability of Rex rabbit fibers and the two key parameters including the treating time and discharge power were optimized during O2 low temperature plasma treatment. The impact of plasma treatment on the surface morphology, physical-chemical properties, and dyeing behavior of Rex rabbit fibers using anionic dyes were investigated by a series of characterization methods such as scanning electron microscopy, atomic force microscopy, Fourier transform infrared–attenuated total reflection, and X-ray photoelectron spectroscopy. The surface dyeability and color fastness were studied by K/S measurement and washing fastness, respectively. The influence of O2 low temperature plasma treatment on the mechanical properties of Rex rabbit fibers was inspected by the tensile strength measurement. The wettability of the samples was evaluated in terms of wetting time and contact angle. The O2 low temperature plasma treatment resulted in a dramatic improvement in wettability of Rex rabbit fibers. X-ray photoelectron spectroscopy and Fourier transform infrared–attenuated total reflection analysis show that oxygen plasma treatment led to a significant increase in the content of sulfur oxides and polar groups such as (–C=O, –OH, and –NH2) on the fiber surface and resulted in reinforced wettability, dyeing rate and dyeing fixation of Rex rabbit fibers.


2011 ◽  
Vol 175-176 ◽  
pp. 312-317 ◽  
Author(s):  
Yu Ren ◽  
Jia Deng ◽  
Zhi Hong Li

In this paper, the polyester fiber surfaces were modified with the combined method of causticization and low-temperature plasma. The effect of Alkali pre-treatment on plasma treatment was studied to investigate the influence of the combined treatment on the properties of the polyester fibers. Through changing the process parameters, such as the temperature of causticization and the plasma treatment duration, the changes of weight loss, mechanical properties, wetting properties and dyeing properties of the polyester fibers after the causticization-plasma treatment were analyzed. In addition, the change of the surface morphology and chemical composition of the polyester fibers after the treatment was investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) analysis respectively. The results showed that the wetting and dyeing properties of the polyester fibers were improved in a higher degree after causticization-plasma treatment than the causticization and plasma treatment independently. Meanwhile, the wetting and dyeing properties were improved more significantly with the increase of the causticization temperature in the causticization-plasma treatment. It was concluded that the pretreatment of the causticization before the low temperature plasma treatment can accelerate the etching and oxidization towards the polyester surface during the plasma treatment.


2012 ◽  
Vol 557-559 ◽  
pp. 1668-1671 ◽  
Author(s):  
Jian Zhong Yang ◽  
Meng Zhao

The performance of the polyphenylene sulfide fiber (PPS) was investigated by low temperature glow discharge plasma . The experimental results show that under the treatment of different plasma conditions, the PPS fiber surfaces appear the varying degree physics and chemical etching. It’s found that the friction coefficient and hydrophilicity of PPS fiber treated by low temperature plasma improve . X-ray photoelectron spectroscopy (XPS) analysis shows that the surface of PPS fiber produced etching, cross-linking, oxidation. Variations of tensile breaking strength of PPS with different parameters are analyzed.


2012 ◽  
Vol 441 ◽  
pp. 49-53
Author(s):  
Hua Qing Wang ◽  
Mei Yang

With the increase in the environmental protection consciousness of people, attention has focused on plasma technology because of its efficiency and environmentally friendliness. In order to improve the dyeing behavior of wool fabrics, surface modification of wool fabrics was carried out using an atmospheric pressure (argon) low temperature plasma treatment (LTP). Morphology and chemical composition analyses of the treated wool fiber surface were carried out by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The effect on the surface properties of wool fabrics treated for different times was evaluated. The results showed that the coloration of wool fabric is improved with an argon atmospheric pressure low temperature plasma (LTP) treatment but the fabric has a lower color fastness to washing and rubbing. This results from the formation of sulfonic groups and the increase in nitrogen content attributed to more severe etching and oxidization on the surface of wool fibers.


2014 ◽  
Vol 1048 ◽  
pp. 440-443
Author(s):  
Naohisa Akashi ◽  
Katsuhiko Hosoi ◽  
Shin-ichi Kuroda

Polytetrafluoroethylene (PTFE) has many excellent engineering applications for its great properties. We investigated the surface of the PTFE membranes treated with atmospheric pressure low temperature plasma in Ar and Ar/H2 to confirm the effectiveness for introducing functional groups as surface modifications. From the results of attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopic analysis and X-ray photoelectron spectroscopy (XPS), it was found that the Ar/H2 plasma was more effective for proceeding defluorination reactions and introducing oxygen moieties compared to Ar plasma under the experimental condition. On the other hand, from the results of scanning electron microscopy (SEM), there were little differences in plasma-treated samples.


Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 194
Author(s):  
Joanna Pawłat ◽  
Piotr Terebun ◽  
Michał Kwiatkowski ◽  
Katarzyna Wolny-Koładka

Sterilization of municipal waste for a raw material for the production of refuse-derived fuel and to protect surface and ground waters against biological contamination during transfer and storage creates a lot of problems. This paper evaluates the antimicrobial potential of non-equilibrium plasma in relation to the selected groups of microorganisms found in humid waste. The proposed research is to determine whether mixed municipal waste used for the production of alternative fuels can be sterilized effectively using low-temperature plasma generated in a gliding arc discharge reactor in order to prevent water contamination and health risk for working staff. This work assesses whether plasma treatment of raw materials in several process variants effectively eliminates or reduces the number of selected groups of microorganisms living in mixed municipal waste. The presence of vegetative bacteria and endospores, mold fungi, actinobacteria Escherichia coli, and facultative pathogens, i.e., Staphylococcus spp., Salmonella spp., Shigella spp., Enterococcus faecalis and Clostridium perfringens in the tested material was microbiologically analyzed. It was found that the plasma treatment differently contributes to the elimination of various kinds of microorganisms in the analyzed raw materials. The effectiveness of sterilization depended mainly on the time of raw materials contact with low-temperature plasma. The results are very promising and require further research to optimize the proposed hygienization process.


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