This paper presents the results of numerical investigation of the current pulses characteristics in SF_(6)/CF_(4)mixtures for the negative point-plane corona discharge.The pressure and the temperature of gas mixtures ...This paper presents the results of numerical investigation of the current pulses characteristics in SF_(6)/CF_(4)mixtures for the negative point-plane corona discharge.The pressure and the temperature of gas mixtures are 0.4 MPa and 300 K,respectively.The CF_(4)content varies from20%to 80%.The 2D axisymmetric geometry with point-plane electrodes is investigated,and the three drift-diffusion equations are solved to predict the characteristics of the negative corona discharge.In addition,Poisson’s equation is coupled with the above three continuity equations to calculate the electric field.In order to calculate the electron impact coefficients,including the Townsend ionization and attachment coefficients,as well as the mobilities and diffusion coefficients for electrons,the two-term Boltzmann equation is solved.The characteristics of three ionic species at five stages of the first current pulse in 60%SF_(6)-40%CF_(4)and20%SF_(6)-80%CF_(4)mixtures are selected to discuss the development mechanism of current pulses.Moreover,the reduced electric field strengths at the corresponding time instants are presented to help understand the discharge process.The current waveform and the total number of three species are compared in all the cases to analyze the effects of the CF_(4)content on the discharge.The reduced electric field strength is also helpful in understanding the effects of CF_(4)content.When the CF_(4)content increases to 80%,the discharge is more intensive and the pulse frequency also increases.展开更多
The low intrinsic activity of Fe/N/C oxygen catalysts restricts their commercial application in the fuel cells technique;herein,we demonstrated the interface engineering of plasmonic induced Fe/N/C-F catalyst with pri...The low intrinsic activity of Fe/N/C oxygen catalysts restricts their commercial application in the fuel cells technique;herein,we demonstrated the interface engineering of plasmonic induced Fe/N/C-F catalyst with primarily enhanced oxygen reduction performance for fuel cells applications.The strong interaction between F and Fe-N4 active sites modifies the catalyst interfacial properties as revealed by X-ray absorption structure spectrum and density functional theory calculations,which changes the electronic structure of Fe-N active site resulting from more atoms around the active site participating in the reaction as well as super-hydrophobicity from C–F covalent bond.The hybrid contribution from active sites and carbon support is proposed to optimize the three-phase microenvironment efficiently in the catalysis electrode,thereby facilitating efficient oxygen reduction performance.High catalytic performance for oxygen reduction and fuel cells practical application catalyzed by Fe/N/C-F catalyst is thus verified,which offers a novel catalyst system for fuel cells technique.展开更多
In this work,the surface modification using a two-steps plasma etching has been developed for enhancing energy conversion performance in polytetrafluoroethylene(PTFE)triboelectric nanogenerator(TENG).Enhancing surface...In this work,the surface modification using a two-steps plasma etching has been developed for enhancing energy conversion performance in polytetrafluoroethylene(PTFE)triboelectric nanogenerator(TENG).Enhancing surface area by a powerful O_(2) and Ar bipolar pulse plasma etching without the use of CF_(4) gas has been demonstrated for the first time.TENG with modified surface PTFE using a sequential two-step O_(2)/Ar plasma has a superior power density of 9.9 W·m^(-2),which is almost thirty times higher than that of a pristine PTFE TENG.The synergistic combination of high surface area and charge trapping sites due to chemical bond defects achieved from the use of a sequential O_(2)/Ar plasma gives rise to the intensified triboelectric charge density and the enhancement of power output of PTFE-based TENG.The effects of plasma species and plasma etching sequence on surface morphologies and surface chemical species were investigated by a field emission scanning electron microscopy(FESEM),atomic force microscopy(AFM),and X-ray photoelectron spectroscopy(XPS).The correlation of surface morphology,chemical structure,and TENG performance was elucidated.In addition,the applications of mechanical energy harvesting for lighting,charging capacitors,keyboard sensing and operating a portable calculator were demonstrated.展开更多
For their distinguished global warming potential（GWP100）and long atmosphere lifespan,CF_4,SF_6 and SF_5CF_3were significant in the field of greenhouse gas research.The details of discharging character and the optima...For their distinguished global warming potential（GWP100）and long atmosphere lifespan,CF_4,SF_6 and SF_5CF_3were significant in the field of greenhouse gas research.The details of discharging character and the optimal parameter were discussed by using a Dielectric Barrier Discharge（DBD）reactor to decompose these potent greenhouse gases in this work.The results showed that SF_6 could be decomposed by 92% under the conditions of 5 min resident time and3000 V applied voltage with the partial pressure of 2.0 k Pa,28.2 k Pa,and 1.8 k Pa for SF_6,air and water vapor,respectively.0.4 k Pa CF_4 could be decomposed by 98.2% for 4 min resident time with 30 k Pa Ar added.The decomposition of SF_5CF_3 was much more effective than that of SF_6 and CF_4and moreover,1.3 k Pa SF_5CF_3,discharged with 30 k PaO_2,Ar and air,could not be detected when the resident time was 80 s,40 s,and 120 s,respectively.All the results indicated that DBD was a feasible technique for the abatement of potent greenhouse gases.展开更多
Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric(PP-g-AA)andpolypropylene membrane were reported.The extents of grafting were controlled by the plasma and polymerizationc...Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric(PP-g-AA)andpolypropylene membrane were reported.The extents of grafting were controlled by the plasma and polymerizationcondition.Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain apolyion complex(PIC).At last,CF_4 plasma was used to give PICs hydrophobic property.The moisture regain and water-repellency of the processed PICs was investigated.The surfaces were characterized using ATR FT-IR and XPS.The resultindicates that the products have very high ability to adsorb moisture,even better than cotton fiber.At the same time,theproducts show excellent hydrophobic property,which can't be wetted by those reagents whose surface tensions were higherthan 327 mN/m.展开更多
基金Natural Science Foundation of Shaanxi Provincial Department of Education(No.21JK0792)National Natural Science Foundation of China(No.51521065)+1 种基金National Key Basic Research Program of China(973 Program)(No.2015CB251001)the Natural Sciences and Engineering Research Council of Canada(NSERC).
文摘This paper presents the results of numerical investigation of the current pulses characteristics in SF_(6)/CF_(4)mixtures for the negative point-plane corona discharge.The pressure and the temperature of gas mixtures are 0.4 MPa and 300 K,respectively.The CF_(4)content varies from20%to 80%.The 2D axisymmetric geometry with point-plane electrodes is investigated,and the three drift-diffusion equations are solved to predict the characteristics of the negative corona discharge.In addition,Poisson’s equation is coupled with the above three continuity equations to calculate the electric field.In order to calculate the electron impact coefficients,including the Townsend ionization and attachment coefficients,as well as the mobilities and diffusion coefficients for electrons,the two-term Boltzmann equation is solved.The characteristics of three ionic species at five stages of the first current pulse in 60%SF_(6)-40%CF_(4)and20%SF_(6)-80%CF_(4)mixtures are selected to discuss the development mechanism of current pulses.Moreover,the reduced electric field strengths at the corresponding time instants are presented to help understand the discharge process.The current waveform and the total number of three species are compared in all the cases to analyze the effects of the CF_(4)content on the discharge.The reduced electric field strength is also helpful in understanding the effects of CF_(4)content.When the CF_(4)content increases to 80%,the discharge is more intensive and the pulse frequency also increases.
基金the National Natural Science Foundation of China(Nos.21203008 and 21975025)Beijing Nature Science Foundation(No.2172051)+1 种基金State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University,and Shenzhen Science and Technology Innovation Committee(No.JCYJ20170817161445322)Thanks for Dr.Lirong Zheng(1W1B@Beijing Synchrotron Radiation Facility)for providing measurement time.We appreciate help from Dr.Jiaou Wang(4B9B@Beijing Synchrotron Radiation Facility)for XANES measurement.XPS measurements were performed in the Analysis&Testing Center,Beijing Institute of Technology.
文摘The low intrinsic activity of Fe/N/C oxygen catalysts restricts their commercial application in the fuel cells technique;herein,we demonstrated the interface engineering of plasmonic induced Fe/N/C-F catalyst with primarily enhanced oxygen reduction performance for fuel cells applications.The strong interaction between F and Fe-N4 active sites modifies the catalyst interfacial properties as revealed by X-ray absorption structure spectrum and density functional theory calculations,which changes the electronic structure of Fe-N active site resulting from more atoms around the active site participating in the reaction as well as super-hydrophobicity from C–F covalent bond.The hybrid contribution from active sites and carbon support is proposed to optimize the three-phase microenvironment efficiently in the catalysis electrode,thereby facilitating efficient oxygen reduction performance.High catalytic performance for oxygen reduction and fuel cells practical application catalyzed by Fe/N/C-F catalyst is thus verified,which offers a novel catalyst system for fuel cells technique.
基金supported by the RNN program of the NANOTEC,NSTDA,Ministry of Higher Education,Science,Research and Innovation(MHESI)and Khon Kaen University,Thailand,the Thailand Research Fund(No.MRG6280196)the Thailand Center of Excellence in Physics(ThEP),and the Basic Research Fund of Khon Kaen University.
文摘In this work,the surface modification using a two-steps plasma etching has been developed for enhancing energy conversion performance in polytetrafluoroethylene(PTFE)triboelectric nanogenerator(TENG).Enhancing surface area by a powerful O_(2) and Ar bipolar pulse plasma etching without the use of CF_(4) gas has been demonstrated for the first time.TENG with modified surface PTFE using a sequential two-step O_(2)/Ar plasma has a superior power density of 9.9 W·m^(-2),which is almost thirty times higher than that of a pristine PTFE TENG.The synergistic combination of high surface area and charge trapping sites due to chemical bond defects achieved from the use of a sequential O_(2)/Ar plasma gives rise to the intensified triboelectric charge density and the enhancement of power output of PTFE-based TENG.The effects of plasma species and plasma etching sequence on surface morphologies and surface chemical species were investigated by a field emission scanning electron microscopy(FESEM),atomic force microscopy(AFM),and X-ray photoelectron spectroscopy(XPS).The correlation of surface morphology,chemical structure,and TENG performance was elucidated.In addition,the applications of mechanical energy harvesting for lighting,charging capacitors,keyboard sensing and operating a portable calculator were demonstrated.
基金supported by National Natural Science Foundation of China(Nos.20507004,21577023)
文摘For their distinguished global warming potential（GWP100）and long atmosphere lifespan,CF_4,SF_6 and SF_5CF_3were significant in the field of greenhouse gas research.The details of discharging character and the optimal parameter were discussed by using a Dielectric Barrier Discharge（DBD）reactor to decompose these potent greenhouse gases in this work.The results showed that SF_6 could be decomposed by 92% under the conditions of 5 min resident time and3000 V applied voltage with the partial pressure of 2.0 k Pa,28.2 k Pa,and 1.8 k Pa for SF_6,air and water vapor,respectively.0.4 k Pa CF_4 could be decomposed by 98.2% for 4 min resident time with 30 k Pa Ar added.The decomposition of SF_5CF_3 was much more effective than that of SF_6 and CF_4and moreover,1.3 k Pa SF_5CF_3,discharged with 30 k PaO_2,Ar and air,could not be detected when the resident time was 80 s,40 s,and 120 s,respectively.All the results indicated that DBD was a feasible technique for the abatement of potent greenhouse gases.
文摘Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric(PP-g-AA)andpolypropylene membrane were reported.The extents of grafting were controlled by the plasma and polymerizationcondition.Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain apolyion complex(PIC).At last,CF_4 plasma was used to give PICs hydrophobic property.The moisture regain and water-repellency of the processed PICs was investigated.The surfaces were characterized using ATR FT-IR and XPS.The resultindicates that the products have very high ability to adsorb moisture,even better than cotton fiber.At the same time,theproducts show excellent hydrophobic property,which can't be wetted by those reagents whose surface tensions were higherthan 327 mN/m.
