The microstructure and Ge-V photoluminescent properties of diamond particles treated by microwave oxygen plasma are investigated.The results show that in the first 5 min of microwave plasma treatment,graphite and diso...The microstructure and Ge-V photoluminescent properties of diamond particles treated by microwave oxygen plasma are investigated.The results show that in the first 5 min of microwave plasma treatment,graphite and disordered carbon on the surface of the particles are etched away,so that diamond with regular crystal plane,smaller lattice stress,and better crystal quality is exposed,producing a Ge-V photoluminescence(PL)intensity 4 times stronger and PL peak FWHM(full width at half maximum)value of 6.6 nm smaller than the as-deposited sample.It is observed that the cycles of‘diamond is converted into graphite and disordered carbon,then the graphite and disordered carbon are etched’can occur with the treatment time further increasing.During these cycles,the particle surface alternately appears smooth and rough,corresponding to the strengthening and weakening of Ge-V PL intensity,respectively,while the PL intensity is always stronger than that of the as-deposited sample.The results suggest that not only graphite but also disordered carbon weakens the Ge-V PL intensity.Our study provides a feasible way of enhancing the Ge-V PL properties and effectively controlling the surface morphology of diamond particle.展开更多
As a promising cancer treatment method,cold atmospheric plasma has received widespread attention in recent years.However,previous research has focused more on how to realize and expand the anti-cancer scope of plasma ...As a promising cancer treatment method,cold atmospheric plasma has received widespread attention in recent years.However,previous research has focused more on how to realize and expand the anti-cancer scope of plasma jet.There are also studies on the killing of small-scale cancer cells,but the effects of plasma jet on normal cells and normal cell clusters have been ignored.Therefore,we proposed a 50μm sized micro-plasma jet device,and used the device to treat melanoma cells(A-375)and human glial cells(HA1800)to evaluate their anti-cancer effects and effects on normal cells.The experimental results show that this kind of micro-plasma jet device can effectively inactivate cancer cells in a short period of time,while having little effect on normal cells.This work provides a certain experimental basis for the application offine plasma jet to clinically inactivate cancer cells.展开更多
The results of experimental studies of carbon materials, which are formed in the plasma of a direct current (DC) arc discharge initiated in open air from the asphaltenes of different origins, extracted from the natura...The results of experimental studies of carbon materials, which are formed in the plasma of a direct current (DC) arc discharge initiated in open air from the asphaltenes of different origins, extracted from the natural asphaltite and from the oil of the Sredne-Ugutskoye Oilfield, are presented. The influence of the initial asphaltene composition on the composition and properties of the resulting carbon materials is analyzed. The initial asphaltenes and the samples of the carbon materials are characterized by the methods of X-ray diffraction, differential thermal analysis, X-ray fluorescence analysis, IR-Fourier spectroscopy, laser diffraction, transmission and scanning electron microscopy. The changes in the composition and structure of the asphaltenes are determined before and after their plasma treatment and the hypotheses are put forward concerning the chemical processes causing the changes in the molecular structure of the samples. As a result of plasma treatment of asphaltenes (100 A, 30 s), it was shown that graphitization occurs, as well as oxidation, and a decrease in sulfur content. Moreover, nanotubes and nano-onions have been detected using electron microscopy. Petroleum asphaltenes after plasma treatment give a less thermostable carbon material, but with a lower content of heteroatoms, and with a large amount of sulfur in the composition of sulfoxide structural fragments. This method is shown to be a promising technology for processing the petroleum feedstock enriched with heavy asphaltene components for the manufacture of carbon nanomaterials: nanotubes, nano-onions and polyhedral graphite.展开更多
Surface hydrophilicity improvement of titanium(Ti)is of great significance for the applications of the important biomaterial.In this study,efficient hydrophilicity on the Ti surface is improved by an air plasma jet ge...Surface hydrophilicity improvement of titanium(Ti)is of great significance for the applications of the important biomaterial.In this study,efficient hydrophilicity on the Ti surface is improved by an air plasma jet generated by a microhollow cathode discharge(MHCD)geometry.Elementary discharge aspects of the plasma jet and surface characteristics of the Ti surface are investigated by varying dissipated power(P_(d)).The results show that the plasma jet can operate in a pulsed mode or a continuous mode,depending on P_(d).The plume length increases with Pdand air flow rate increasing.By optical emission spectroscopy,plasma parameters as a function of Pdare investigated.After plasma treatment,water contact angel(WCA)of the Ti sample decreases to a minimum value of 15°with Pdincreasing.In addition,the surface topography,roughness,and content of chemical composition are investigated by scanning electron microscopy(SEM),atomic force microscopy(AFM),and x-ray photoelectron spectroscopy(XPS)with Pdincreasing.The results show that Ti-O bond and O-H group on the Ti surface are beneficial to the improvement of the hydrophilicity of Ti surface.展开更多
This letter showcases the successful fabrication of an enhancement-mode(E-mode)buried p-channel GaN fieldeffect-transistor on a standard p-GaN/AlGaN/GaN-on-Si power HEMT substrate.The transistor exhibits a threshold v...This letter showcases the successful fabrication of an enhancement-mode(E-mode)buried p-channel GaN fieldeffect-transistor on a standard p-GaN/AlGaN/GaN-on-Si power HEMT substrate.The transistor exhibits a threshold voltage(VTH)of−3.8 V,a maximum ON-state current(ION)of 1.12 mA/mm,and an impressive ION/IOFF ratio of 10^(7).To achieve these remarkable results,an H plasma treatment was strategically applied to the gated p-GaN region,where a relatively thick GaN layer(i.e.,70 nm)was kept intact without aggressive gate recess.Through this treatment,the top portion of the GaN layer was converted to be hole-free,leaving only the bottom portion p-type and spatially separated from the etched GaN surface and gateoxide/GaN interface.This approach allows for E-mode operation while retaining high-quality p-channel characteristics.展开更多
Economical water electrolysis requires highly active non-noble electrocatalysts to overcome the sluggish kinetics of the two half-cell reactions,oxygen evolution reaction,and hydrogen evolution reaction.Although inten...Economical water electrolysis requires highly active non-noble electrocatalysts to overcome the sluggish kinetics of the two half-cell reactions,oxygen evolution reaction,and hydrogen evolution reaction.Although intensive efforts have been committed to achieve a hydrogen economy,the expensive noble metal-based catalysts remain under consideration.Therefore,the engineering of self-supported electrocatalysts prepared using a direct growth strategy on three-dimensional(3D)nickel foam(NF)as a conductive substrate has garnered significant interest.This is due to the large active surface area and 3D porous network offered by these electrocatalysts,which can enhance the synergistic eff ect between the catalyst and the substrate,as well as improve electrocatalytic performance.Hydrothermal-assisted growth,microwave heating,electrodeposition,and other physical methods(i.e.,chemical vapor deposition and plasma treatment)have been applied to NF to fabricate competitive electrocatalysts with low overpotential and high stability.In this review,recent advancements in the development of self-supported electrocatalysts on 3D NF are described.Finally,we provide future perspectives of self-supported electrode platforms in electrochemical water splitting.展开更多
Hydrogenated amorphous carbon films were fabricated by using layer-by-layer deposition method and hydrogen dilution method in a small d.c.-assisted plasma enhanced chemical vapor deposition system. It was found that t...Hydrogenated amorphous carbon films were fabricated by using layer-by-layer deposition method and hydrogen dilution method in a small d.c.-assisted plasma enhanced chemical vapor deposition system. It was found that the hydrogen plasma treatment could change the sp2/sp3 ratio to some extent by chemical etching. The improvements of field emission characteristics were observed compared with that from conventionally deposited a-C films, which can be attributed to the large field enhancement effect due to the inhomogeneous distribution of nanometer scale sp2 clusters and the reduction of the surface emission barrier due to the hydrogen termination.展开更多
Ni-Co bimetallic catalysts with different Ni/Co content were derived from cold plasma jet decomposition and reduction of hydrotalcite-like compounds containing Ni,Co,Mg and Al,and their catalytic performance was inves...Ni-Co bimetallic catalysts with different Ni/Co content were derived from cold plasma jet decomposition and reduction of hydrotalcite-like compounds containing Ni,Co,Mg and Al,and their catalytic performance was investigated with dry reforming of methane.Experimental results showed that the hydrotalcite-like precursors could be completely decomposed and partly reduced by cold plasma jet,and the Nicontained catalysts exhibited much higher activity than the catalyst without Ni.Especially,the catalyst with Ni/Co ratio of 8/2 achieved not only the highest conversions of 80.3%and 69.3%for CH4 and CO2,respectively,but also the best stability in 100 h testing.The catalysts were characterized by XRD,XPS,TEM and N2 adsorption techniques,and the results showed that the better performance of the 8Ni2Co bimetallic catalyst was attributed to its higher metal dispersion,smaller metal particle size,as well as the interaction effect between Ni and Co,which were brought by the special catalyst preparation method.展开更多
An atmospheric pressure argon plasma brush with air addition is employed to treat polyethylene terephthalate(PET)surface in order to improve its hydrophilicity.Results indicate that the plasma plume generated by the p...An atmospheric pressure argon plasma brush with air addition is employed to treat polyethylene terephthalate(PET)surface in order to improve its hydrophilicity.Results indicate that the plasma plume generated by the plasma brush presents periodically pulsed current despite a direct current voltage is applied.Voltage-current curve reveals that there is a transition from a Townsend discharge regime to a glow one during one discharge period.Optical emission spectrum indicates that more oxygen atoms are produced in the plume with increasing air content,which leads to the better hydrophilicity of PET surface after plasma treatment.Besides,an aging behavior is also observed.The hydrophilicity improvement is attributed to the production of oxygen functional groups,which increase in number with increasing air content.Moreover,some grain-like structures are observed on the treated PET surface,and its mean roughness increases with increasing air content.These results are of great importance for the hydrophilicity improvement of PET surface with a large scale.展开更多
In this study, Ni/YZrOcatalysts prepared with impregnation method and treated by dielectric barrier discharge plasma(DBD) in different atmospheres have been investigated for methane dry reforming. It is revealed by H-...In this study, Ni/YZrOcatalysts prepared with impregnation method and treated by dielectric barrier discharge plasma(DBD) in different atmospheres have been investigated for methane dry reforming. It is revealed by H-TPR that plasma treatment can enhance the interaction between Ni O/Ni particles and the YZrOpyrochlore support. Therefore, catalysts with smaller Ni O and Ni grains sizes, higher metallic Ni active surface areas can be achieved, as evidenced by XRD, TEM and Hadsorption-desorption measurements. As a consequence, the plasma-treated catalysts show significantly improved activity, stability and coke resistance, as testified by the TEM and TGA-DSC results. Plasma treatment in H/Ar gas mixture is found to be the best condition to prepare Ni/YZrO, which can be used to obtain a catalyst with the highest activity, stability and most potent coke resistance. It is believed that the smaller Ni grain size and higher metallic Ni active surface area induced by plasma treatment are the inherent reasons accounting for the promoted reaction performance of the Ni/YZrOpyrochlore catalysts.展开更多
Reported in this paper is a feasibility study on the injection of plasma induced N radicals for the abatement of NO and NOx present in the actual diesel exhaust. The radical laden diesel exhaust was further treated by...Reported in this paper is a feasibility study on the injection of plasma induced N radicals for the abatement of NO and NOx present in the actual diesel exhaust. The radical laden diesel exhaust was further treated by discharge plasma in a dielectric barrier discharge reactor. N radicals were produced in a separate plasma reactor filled with BaTiO3 pellets and were then injected into the treatment zone, There was a significant improvement in the efficiency when the radicals were injected compared to that when there was no radical injection. The efficiency of NOx removal at 0 load with plasma alone was 14% whereas with the injection of N radicals it went up to 38%, The results of the experiments conducted at different loads are discussed,展开更多
Commercial carbon cloth(CC)is an ideal electrocatalysis material to produce oxygen evolution reaction(OER)due to its high conductive and 3D flexible structure,but the lacked active sites limit its application.For impr...Commercial carbon cloth(CC)is an ideal electrocatalysis material to produce oxygen evolution reaction(OER)due to its high conductive and 3D flexible structure,but the lacked active sites limit its application.For improving its OER performance,the present study proposed an effective method combining plasma and acid treatment to introduce oxygen-containing functional groups and produce more active sites on its surface.Compared to the pristine CC,the plasma and acid treated carbon cloth(PN-CC)delivers a reduced overpotential by 34.6%to achieve current density of 10 mA cm^(−2).The Tafel slope declines from 97.5 mV dec^(–1)(pristine CC)to 55.9 mV dec–1(PN-CC),showing an increased OER kinetic.Additionally,PN-CC electrocatalyst shows outstanding stability after 5000 cycles or 25000 s.The combination of plasma and acid treatment shows a significant potential in surface modification for electrocatalysts.展开更多
Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM was used to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result show...Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM was used to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result shows that the surface polarity of carbon fibers was modified by cold plasma treatment, which increases the impregnation of PET braided carbon fibers during the process of resin flowing, improves the interfacial properties of RTM composites, and therefore enhances the mechanical properties of the KTM composites.展开更多
In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chlo- ride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Py...In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chlo- ride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared (FT4R) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR- FTIR) spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy (AFM) and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.展开更多
The 10%Ni/Al_2O_3 catalyst for partial oxidation of methane was treated byDBD (dielectric barrier discharge) plasma in a continuous system under atmospheric pressure and roomtemperature by flowing He. It was found tha...The 10%Ni/Al_2O_3 catalyst for partial oxidation of methane was treated byDBD (dielectric barrier discharge) plasma in a continuous system under atmospheric pressure and roomtemperature by flowing He. It was found that 10%Ni/Al_2O_3 catalyst treated by plasma presents ahigher catalytic activity and an enhanced stability than the catalysts prepared without plasmatreatment. The methane conversion over the catalyst treated by plasma is 3%-5% higher than thecatalysts untreated by plasma. Moreover, the enhanced dispersion of the catalyst can be achieved byplasma treatment, which can improve the interaction between active species and supports, catalyticactivity and the resistance to carbon deposition.展开更多
Plasma treatment can be used to modify the structure of natural fibre like jute for a variety of applications. Environmentally friendly jute fibre was treated with argon and oxygen plasma. The treated samples were cha...Plasma treatment can be used to modify the structure of natural fibre like jute for a variety of applications. Environmentally friendly jute fibre was treated with argon and oxygen plasma. The treated samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and optical microscope. The macromolecular and microstructural changes in cellulose confirmed the change by plasma treatment. The XRD results confirmed that the crystal size and the crystallinity of the plasma treated fibre increased. Argon plasma treated fibre had a smooth and compact surface, compared to oxygen plasma treated fibre. The maximum stain (i.e. stress) concentrated in the oxygen plasma treated fibre. Optical micrographs showed the oxygen plasma treated fibre tended to rupture due to higher strain (i.e., stress) compared to fibre with argon plasma treatment. FTIR results also provided the evidence of change in the chemical constituents with plasma treatment.展开更多
This paper reports fluorine plasma treatment enhancement-mode HEMTs (high electronic mobility transistors) EHEMTs and conventional depletion-mode HEMTs DHEMTs fabricated on one wafer using separate litho-photography...This paper reports fluorine plasma treatment enhancement-mode HEMTs (high electronic mobility transistors) EHEMTs and conventional depletion-mode HEMTs DHEMTs fabricated on one wafer using separate litho-photography technology. It finds that fluorine plasma etches the AlGaN at a slow rate by capacitance-voltage measurement. Using capacitance-frequency measurement, it finds one type of trap in conventional DHEMTs with TT = (0.5 - 6) ms and DT : (1 - 5)×10^13 cm^-2. eV^-1. Two types of trap are found in fluorine plasma treatment EHEMTs, fast with TW(f)= (0.2 - 2) μs and slow with TT(s) = (0.5 - 6) ms. The density of trap states evaluated on the EHEMTs is Dw(f) : (1 - 3) × 10^12 cm^-2. eV^-1 and DT(s) =(2 - 6) × 10^12 cm-2. eV-1 for the fast and slow traps, respectively. The result shows that the fluorine plasma treatment reduces the slow trap density by about one order, but introduces a new type of fast trap. The slow trap is suggested to be a surface trap, related to the gate leakage current.展开更多
Application of plasma chemistry for gas cleaning is gaining prominence in recent years, mainly from an energy efficiency point of view. In this paper we conducted a comparative study of NO/NOx removal using two differ...Application of plasma chemistry for gas cleaning is gaining prominence in recent years, mainly from an energy efficiency point of view. In this paper we conducted a comparative study of NO/NOx removal using two different types of dielectric barrier discharge electrodes, wire- cylinder reactor, pipe-cylinder reactor. Investigations were first carried out with synthetic gases to obtain the baseline information on the NO/NOx removal with respect to the two geometries studied. Further, experiments were carried out with raw diesel exhaust under loaded condition. A high NOx removal efficiency of 90% was observed for the pipe-cylinder reactor as compared to that of 53.4% for the wire-cylinder reactor. Furthermore, for the same energy consumed per NO molecule (about 73 eV/NO molecule), the removal efficiency increased from 67% for the wire- cylinder to about 98% for the pipe-cylinder which was quite appreciable.展开更多
Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculat...Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculated cotton fabrics were investigated. Oxygen plasma treatment completely sterilized the cotton fabrics inoculated with various concentrations of staphylococcus aureus. Also, the influence of plasma treatment on physical properties of fabrics was examined. It was found that the plasma treatment did not affect ultimate tensile strength and surface morphology of the fabrics because it took advantage of relatively low plasma temperature.展开更多
This paper presents the results of aluminum surface treatment by diffuse coplanar surface barrier discharge. The goals are to study the effectiveness of the plasma treatment and the dependence of its efficiency on ope...This paper presents the results of aluminum surface treatment by diffuse coplanar surface barrier discharge. The goals are to study the effectiveness of the plasma treatment and the dependence of its efficiency on operation parameters, such as sample-to-electrode distance, treatment time or gas atmosphere. Three types of aluminum materials (bricks, sheets and thin films) were tested to ensure the reliability of the treatment. The changes in the surface properties were characterized by the surface free energy, atomic force microscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) and X-ray photoelectron spec- troscopy (XPS). The influence of aging effect on the treatment was also measured and discussed.展开更多
基金the Key Project of the National Natural Science Foundation of China(Grant No.U1809210)the National Key Research and Development Program of China(Grant No.2016YFE0133200)+3 种基金the Belt and Road Initiative International Cooperation Project from Key Research and Development Program of Zhejiang Province,China(Grant No.2018C04021)the European Union’s Horizon 2020 Research and Innovation Staff Exchange Scheme(Grant No.734578)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY18E020013)the International Science Technology Cooperation Program,China(Grant No.2014DFR51160).
文摘The microstructure and Ge-V photoluminescent properties of diamond particles treated by microwave oxygen plasma are investigated.The results show that in the first 5 min of microwave plasma treatment,graphite and disordered carbon on the surface of the particles are etched away,so that diamond with regular crystal plane,smaller lattice stress,and better crystal quality is exposed,producing a Ge-V photoluminescence(PL)intensity 4 times stronger and PL peak FWHM(full width at half maximum)value of 6.6 nm smaller than the as-deposited sample.It is observed that the cycles of‘diamond is converted into graphite and disordered carbon,then the graphite and disordered carbon are etched’can occur with the treatment time further increasing.During these cycles,the particle surface alternately appears smooth and rough,corresponding to the strengthening and weakening of Ge-V PL intensity,respectively,while the PL intensity is always stronger than that of the as-deposited sample.The results suggest that not only graphite but also disordered carbon weakens the Ge-V PL intensity.Our study provides a feasible way of enhancing the Ge-V PL properties and effectively controlling the surface morphology of diamond particle.
基金supported by the National Natural Science Foundation of China under Grant Number 62163009 and 61864001the Natural Science Foundation of GuangXi under Grant Number 2021JJD170019+2 种基金the Foundation of Guangxi Key Laboratory of Automatic Detecting Technology and Instruments(Guilin University of Electronic Technology)under Grant Number YQ23103Innovation Project of GuangXi Graduate Education under Grant Nos.YCSW2022277 and 2023YCXS184Guangxi Major Scientific and Technological Innovation Base(Guilin University of Electronic Technology)under Grant 231002-k.
文摘As a promising cancer treatment method,cold atmospheric plasma has received widespread attention in recent years.However,previous research has focused more on how to realize and expand the anti-cancer scope of plasma jet.There are also studies on the killing of small-scale cancer cells,but the effects of plasma jet on normal cells and normal cell clusters have been ignored.Therefore,we proposed a 50μm sized micro-plasma jet device,and used the device to treat melanoma cells(A-375)and human glial cells(HA1800)to evaluate their anti-cancer effects and effects on normal cells.The experimental results show that this kind of micro-plasma jet device can effectively inactivate cancer cells in a short period of time,while having little effect on normal cells.This work provides a certain experimental basis for the application offine plasma jet to clinically inactivate cancer cells.
基金funded by a grant from the Russian Science Foundation(Project No.22-13-20016)carried out at the Surgut State University and Tomsk Polytechnic University.
文摘The results of experimental studies of carbon materials, which are formed in the plasma of a direct current (DC) arc discharge initiated in open air from the asphaltenes of different origins, extracted from the natural asphaltite and from the oil of the Sredne-Ugutskoye Oilfield, are presented. The influence of the initial asphaltene composition on the composition and properties of the resulting carbon materials is analyzed. The initial asphaltenes and the samples of the carbon materials are characterized by the methods of X-ray diffraction, differential thermal analysis, X-ray fluorescence analysis, IR-Fourier spectroscopy, laser diffraction, transmission and scanning electron microscopy. The changes in the composition and structure of the asphaltenes are determined before and after their plasma treatment and the hypotheses are put forward concerning the chemical processes causing the changes in the molecular structure of the samples. As a result of plasma treatment of asphaltenes (100 A, 30 s), it was shown that graphitization occurs, as well as oxidation, and a decrease in sulfur content. Moreover, nanotubes and nano-onions have been detected using electron microscopy. Petroleum asphaltenes after plasma treatment give a less thermostable carbon material, but with a lower content of heteroatoms, and with a large amount of sulfur in the composition of sulfoxide structural fragments. This method is shown to be a promising technology for processing the petroleum feedstock enriched with heavy asphaltene components for the manufacture of carbon nanomaterials: nanotubes, nano-onions and polyhedral graphite.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51977057 and 11875121)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2020201025 and A2022201036)+2 种基金the Natural Science Interdisciplinary Research Program of Hebei University,China(Grant Nos.DXK201908 and DXK202011)the Postgraduate’s Innovation Fund Project of Hebei Province,China(Grant Nos.CXZZBS2019023 and CXZZBS2019029)the Post-graduate’s Innovation Fund Project of Hebei University,China(Grant Nos.HBU2021ss063,HBU2021bs011,and HBU2022bs004)。
文摘Surface hydrophilicity improvement of titanium(Ti)is of great significance for the applications of the important biomaterial.In this study,efficient hydrophilicity on the Ti surface is improved by an air plasma jet generated by a microhollow cathode discharge(MHCD)geometry.Elementary discharge aspects of the plasma jet and surface characteristics of the Ti surface are investigated by varying dissipated power(P_(d)).The results show that the plasma jet can operate in a pulsed mode or a continuous mode,depending on P_(d).The plume length increases with Pdand air flow rate increasing.By optical emission spectroscopy,plasma parameters as a function of Pdare investigated.After plasma treatment,water contact angel(WCA)of the Ti sample decreases to a minimum value of 15°with Pdincreasing.In addition,the surface topography,roughness,and content of chemical composition are investigated by scanning electron microscopy(SEM),atomic force microscopy(AFM),and x-ray photoelectron spectroscopy(XPS)with Pdincreasing.The results show that Ti-O bond and O-H group on the Ti surface are beneficial to the improvement of the hydrophilicity of Ti surface.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2020321)the National Natural Science Foundation of China(Grant No.92163204).
文摘This letter showcases the successful fabrication of an enhancement-mode(E-mode)buried p-channel GaN fieldeffect-transistor on a standard p-GaN/AlGaN/GaN-on-Si power HEMT substrate.The transistor exhibits a threshold voltage(VTH)of−3.8 V,a maximum ON-state current(ION)of 1.12 mA/mm,and an impressive ION/IOFF ratio of 10^(7).To achieve these remarkable results,an H plasma treatment was strategically applied to the gated p-GaN region,where a relatively thick GaN layer(i.e.,70 nm)was kept intact without aggressive gate recess.Through this treatment,the top portion of the GaN layer was converted to be hole-free,leaving only the bottom portion p-type and spatially separated from the etched GaN surface and gateoxide/GaN interface.This approach allows for E-mode operation while retaining high-quality p-channel characteristics.
基金supported by The Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (No. 2023VCB0014)The National Natural Science Foundation of China (No. 52203284)Shenzhen Science and Technology Program (Nos. GJHZ20220913143801003 and RCBS20221008093057026)
文摘Economical water electrolysis requires highly active non-noble electrocatalysts to overcome the sluggish kinetics of the two half-cell reactions,oxygen evolution reaction,and hydrogen evolution reaction.Although intensive efforts have been committed to achieve a hydrogen economy,the expensive noble metal-based catalysts remain under consideration.Therefore,the engineering of self-supported electrocatalysts prepared using a direct growth strategy on three-dimensional(3D)nickel foam(NF)as a conductive substrate has garnered significant interest.This is due to the large active surface area and 3D porous network offered by these electrocatalysts,which can enhance the synergistic eff ect between the catalyst and the substrate,as well as improve electrocatalytic performance.Hydrothermal-assisted growth,microwave heating,electrodeposition,and other physical methods(i.e.,chemical vapor deposition and plasma treatment)have been applied to NF to fabricate competitive electrocatalysts with low overpotential and high stability.In this review,recent advancements in the development of self-supported electrocatalysts on 3D NF are described.Finally,we provide future perspectives of self-supported electrode platforms in electrochemical water splitting.
基金supported by the NSFof China(59802004)Jiangsu Province,China(BK99047)+1 种基金RGC of Hongkong(No.CUHK 4173/98E)support of Groucher Foundation of Hong Kong
文摘Hydrogenated amorphous carbon films were fabricated by using layer-by-layer deposition method and hydrogen dilution method in a small d.c.-assisted plasma enhanced chemical vapor deposition system. It was found that the hydrogen plasma treatment could change the sp2/sp3 ratio to some extent by chemical etching. The improvements of field emission characteristics were observed compared with that from conventionally deposited a-C films, which can be attributed to the large field enhancement effect due to the inhomogeneous distribution of nanometer scale sp2 clusters and the reduction of the surface emission barrier due to the hydrogen termination.
基金supported by the National Natural Science Foundation of China(11075113)
文摘Ni-Co bimetallic catalysts with different Ni/Co content were derived from cold plasma jet decomposition and reduction of hydrotalcite-like compounds containing Ni,Co,Mg and Al,and their catalytic performance was investigated with dry reforming of methane.Experimental results showed that the hydrotalcite-like precursors could be completely decomposed and partly reduced by cold plasma jet,and the Nicontained catalysts exhibited much higher activity than the catalyst without Ni.Especially,the catalyst with Ni/Co ratio of 8/2 achieved not only the highest conversions of 80.3%and 69.3%for CH4 and CO2,respectively,but also the best stability in 100 h testing.The catalysts were characterized by XRD,XPS,TEM and N2 adsorption techniques,and the results showed that the better performance of the 8Ni2Co bimetallic catalyst was attributed to its higher metal dispersion,smaller metal particle size,as well as the interaction effect between Ni and Co,which were brought by the special catalyst preparation method.
基金supported by National Natural Science Foundation of China(Nos.11875121,11575050 and51977057)the Midwest Universities Comprehensive Strength Promotion Project+4 种基金the Natural Science Foundation of Hebei Province,China(Nos.A2019201100,A2020201025)College Hundred Outstanding Innovative Talent Support Program of Hebei Education Bureau(No.SLRC2017021)Post-graduate’s Innovation Fund Project of Hebei Province(Nos.CXZZBS2019023,CXZZBS2019029)the Natural Science Interdisciplinary Research Program of Hebei University(No.DXK201908)Post-graduate’s Innovation Fund Project of Hebei University(No.HBU2021bs011)。
文摘An atmospheric pressure argon plasma brush with air addition is employed to treat polyethylene terephthalate(PET)surface in order to improve its hydrophilicity.Results indicate that the plasma plume generated by the plasma brush presents periodically pulsed current despite a direct current voltage is applied.Voltage-current curve reveals that there is a transition from a Townsend discharge regime to a glow one during one discharge period.Optical emission spectrum indicates that more oxygen atoms are produced in the plume with increasing air content,which leads to the better hydrophilicity of PET surface after plasma treatment.Besides,an aging behavior is also observed.The hydrophilicity improvement is attributed to the production of oxygen functional groups,which increase in number with increasing air content.Moreover,some grain-like structures are observed on the treated PET surface,and its mean roughness increases with increasing air content.These results are of great importance for the hydrophilicity improvement of PET surface with a large scale.
基金supported by the National Natural Science Foundation of China (21567016, 21566022, 21263015)the Natural Science Foundation of Jiangxi Province (20151BBE50006, 20151BAB203024)the Education Department of Jiangxi Province (KJLD14005, GJJ150016)
文摘In this study, Ni/YZrOcatalysts prepared with impregnation method and treated by dielectric barrier discharge plasma(DBD) in different atmospheres have been investigated for methane dry reforming. It is revealed by H-TPR that plasma treatment can enhance the interaction between Ni O/Ni particles and the YZrOpyrochlore support. Therefore, catalysts with smaller Ni O and Ni grains sizes, higher metallic Ni active surface areas can be achieved, as evidenced by XRD, TEM and Hadsorption-desorption measurements. As a consequence, the plasma-treated catalysts show significantly improved activity, stability and coke resistance, as testified by the TEM and TGA-DSC results. Plasma treatment in H/Ar gas mixture is found to be the best condition to prepare Ni/YZrO, which can be used to obtain a catalyst with the highest activity, stability and most potent coke resistance. It is believed that the smaller Ni grain size and higher metallic Ni active surface area induced by plasma treatment are the inherent reasons accounting for the promoted reaction performance of the Ni/YZrOpyrochlore catalysts.
文摘Reported in this paper is a feasibility study on the injection of plasma induced N radicals for the abatement of NO and NOx present in the actual diesel exhaust. The radical laden diesel exhaust was further treated by discharge plasma in a dielectric barrier discharge reactor. N radicals were produced in a separate plasma reactor filled with BaTiO3 pellets and were then injected into the treatment zone, There was a significant improvement in the efficiency when the radicals were injected compared to that when there was no radical injection. The efficiency of NOx removal at 0 load with plasma alone was 14% whereas with the injection of N radicals it went up to 38%, The results of the experiments conducted at different loads are discussed,
基金by Shenzhen Science and Technology Innovation Committee(No.JCYJ20180507182200750)。
文摘Commercial carbon cloth(CC)is an ideal electrocatalysis material to produce oxygen evolution reaction(OER)due to its high conductive and 3D flexible structure,but the lacked active sites limit its application.For improving its OER performance,the present study proposed an effective method combining plasma and acid treatment to introduce oxygen-containing functional groups and produce more active sites on its surface.Compared to the pristine CC,the plasma and acid treated carbon cloth(PN-CC)delivers a reduced overpotential by 34.6%to achieve current density of 10 mA cm^(−2).The Tafel slope declines from 97.5 mV dec^(–1)(pristine CC)to 55.9 mV dec–1(PN-CC),showing an increased OER kinetic.Additionally,PN-CC electrocatalyst shows outstanding stability after 5000 cycles or 25000 s.The combination of plasma and acid treatment shows a significant potential in surface modification for electrocatalysts.
文摘Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM was used to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result shows that the surface polarity of carbon fibers was modified by cold plasma treatment, which increases the impregnation of PET braided carbon fibers during the process of resin flowing, improves the interfacial properties of RTM composites, and therefore enhances the mechanical properties of the KTM composites.
文摘In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chlo- ride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared (FT4R) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR- FTIR) spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy (AFM) and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.
基金This work was supported by National Science Foundation Committee of China (Grant number 20106013).
文摘The 10%Ni/Al_2O_3 catalyst for partial oxidation of methane was treated byDBD (dielectric barrier discharge) plasma in a continuous system under atmospheric pressure and roomtemperature by flowing He. It was found that 10%Ni/Al_2O_3 catalyst treated by plasma presents ahigher catalytic activity and an enhanced stability than the catalysts prepared without plasmatreatment. The methane conversion over the catalyst treated by plasma is 3%-5% higher than thecatalysts untreated by plasma. Moreover, the enhanced dispersion of the catalyst can be achieved byplasma treatment, which can improve the interaction between active species and supports, catalyticactivity and the resistance to carbon deposition.
文摘Plasma treatment can be used to modify the structure of natural fibre like jute for a variety of applications. Environmentally friendly jute fibre was treated with argon and oxygen plasma. The treated samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and optical microscope. The macromolecular and microstructural changes in cellulose confirmed the change by plasma treatment. The XRD results confirmed that the crystal size and the crystallinity of the plasma treated fibre increased. Argon plasma treated fibre had a smooth and compact surface, compared to oxygen plasma treated fibre. The maximum stain (i.e. stress) concentrated in the oxygen plasma treated fibre. Optical micrographs showed the oxygen plasma treated fibre tended to rupture due to higher strain (i.e., stress) compared to fibre with argon plasma treatment. FTIR results also provided the evidence of change in the chemical constituents with plasma treatment.
基金Project supported by the National Natural Science Foundation of China(Grant No.60736033)the Fundamental Research Funds for the Central Universities(Grant No.JY10000904009)
文摘This paper reports fluorine plasma treatment enhancement-mode HEMTs (high electronic mobility transistors) EHEMTs and conventional depletion-mode HEMTs DHEMTs fabricated on one wafer using separate litho-photography technology. It finds that fluorine plasma etches the AlGaN at a slow rate by capacitance-voltage measurement. Using capacitance-frequency measurement, it finds one type of trap in conventional DHEMTs with TT = (0.5 - 6) ms and DT : (1 - 5)×10^13 cm^-2. eV^-1. Two types of trap are found in fluorine plasma treatment EHEMTs, fast with TW(f)= (0.2 - 2) μs and slow with TT(s) = (0.5 - 6) ms. The density of trap states evaluated on the EHEMTs is Dw(f) : (1 - 3) × 10^12 cm^-2. eV^-1 and DT(s) =(2 - 6) × 10^12 cm-2. eV-1 for the fast and slow traps, respectively. The result shows that the fluorine plasma treatment reduces the slow trap density by about one order, but introduces a new type of fast trap. The slow trap is suggested to be a surface trap, related to the gate leakage current.
文摘Application of plasma chemistry for gas cleaning is gaining prominence in recent years, mainly from an energy efficiency point of view. In this paper we conducted a comparative study of NO/NOx removal using two different types of dielectric barrier discharge electrodes, wire- cylinder reactor, pipe-cylinder reactor. Investigations were first carried out with synthetic gases to obtain the baseline information on the NO/NOx removal with respect to the two geometries studied. Further, experiments were carried out with raw diesel exhaust under loaded condition. A high NOx removal efficiency of 90% was observed for the pipe-cylinder reactor as compared to that of 53.4% for the wire-cylinder reactor. Furthermore, for the same energy consumed per NO molecule (about 73 eV/NO molecule), the removal efficiency increased from 67% for the wire- cylinder to about 98% for the pipe-cylinder which was quite appreciable.
基金Iran National Science Foundation(INSF) for providing grant of members
文摘Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculated cotton fabrics were investigated. Oxygen plasma treatment completely sterilized the cotton fabrics inoculated with various concentrations of staphylococcus aureus. Also, the influence of plasma treatment on physical properties of fabrics was examined. It was found that the plasma treatment did not affect ultimate tensile strength and surface morphology of the fabrics because it took advantage of relatively low plasma temperature.
基金supported by the Czech Science Foundation(Project No.104/08/02290)
文摘This paper presents the results of aluminum surface treatment by diffuse coplanar surface barrier discharge. The goals are to study the effectiveness of the plasma treatment and the dependence of its efficiency on operation parameters, such as sample-to-electrode distance, treatment time or gas atmosphere. Three types of aluminum materials (bricks, sheets and thin films) were tested to ensure the reliability of the treatment. The changes in the surface properties were characterized by the surface free energy, atomic force microscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) and X-ray photoelectron spec- troscopy (XPS). The influence of aging effect on the treatment was also measured and discussed.