The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that ...The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La 2O 3 is dissociated, resulting in partial reduction of the lanthanum to LaO x(x <3/2). In addition, the lanthanum rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo La 2O 3 cathode.展开更多
The modification mechanism of the water/alcohol cathode interlayer is one of the most complicated problems in the field of organic photovoltaics,which has not been clearly elucidated yet;this greatly restricts the fur...The modification mechanism of the water/alcohol cathode interlayer is one of the most complicated problems in the field of organic photovoltaics,which has not been clearly elucidated yet;this greatly restricts the further enhancement of the PCE for polymer solar cells.Herein,we clarified the different effects of PFN and its derivatives,namely,poly[(9,9-bis(3’-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)](PFN-Br) in modifying fullerene-free PSCs.It is found for the first time that doping on IT-4F by the amino group of PFN leads to the unfavorable charge accumulation,and hence,forms a dense layer of electronegative molecule due to the poor electron transport capacity of the non-fullerene acceptor IT-4F.The electronegative molecular layer can block the electron transfer from the active layer to the interlayer and cause serious charge recombination at the active layer/cathode interface.This mechanism could be verified by the ESR measurement and electron-only devices.By replacing PFN with PFN-Br,the excessive doping effect between the cathode interlayer and IT-4F is eliminated,by which the charge transport and collection can be greatly improved.As a result,a high PCE of 13.5%was achieved in the fullerene-free PSCs.展开更多
Rechargeable magnesium batteries(RMBs)hold promise for offering higher volumetric energy density and safety features,attracting increasing research interest as the next post lithium-ion batteries.Developing high perfo...Rechargeable magnesium batteries(RMBs)hold promise for offering higher volumetric energy density and safety features,attracting increasing research interest as the next post lithium-ion batteries.Developing high performance cathode material by inducing multi-electron reaction process as well as maintaining structural stability is the key to the development and application of RMBs.Herein,multielectron reaction occurred in VS_(4)by simple W doping strategy.W doping induces valence of partial V as V^(2+)and V^(3+)in VS_(4)structure,and then stimulates electrochemical reaction involving multi-electrons in 0.5%W-V-S.The flower-like microsphere morphology as well as rich S vacancies is also modulated by W doping to neutralize structure change in such multi-electron reaction process.The fabricated 0.5%W-V-S delivers higher specific capacity(149.3 m A h g^(-1)at 50 m A g^(-1),which is 1.6 times higher than that of VS_(4)),superior rate capability(76 mA h g^(-1)at 1000 mA g^(-1)),and stable cycling performance(1500cycles with capacity retention ratio of 93.8%).Besides that,pesudocapaticance-like contribution analysis as well as galvanostatic intermittent titration technique(GITT)further confirms the enhanced Mg^(2+)storage kinetics during such multi-electron involved electrochemical reaction process.Such discovery provides new insights into the designing of multi-electron reaction process in cathode as well as neutralizing structural change during such reaction for realizing superior electrochemical performance in energy storage devices.展开更多
Low-temperature zinc batteries(LT-ZIBs)based on aqueous electrolytes show great promise for practical applications owing to their natural resource abundance and low cost.However,they suffer from sluggish kinetics with...Low-temperature zinc batteries(LT-ZIBs)based on aqueous electrolytes show great promise for practical applications owing to their natural resource abundance and low cost.However,they suffer from sluggish kinetics with elevated energy barriers due to the dissociation of bulky Zn(H2O)62+solvation structure and free Zn2+diffusion,resulting in unsatisfactory lifespan and performance.Herein,dissimilar to solvation shell tuning or layer spacing enlargement engineering,delocalized electrons in cathode through constructing intrinsic defect engineering is proposed to achieve a rapid electrocatalytic desolvation to obtain free Zn2+for insertion/extraction.As revealed by density functional theory calculations and interfacial spectroscopic characterizations,the intrinsic delocalized electron distribution propels the Zn(H2O)62+dissociation,forming a reversible interphase and facilitating Zn2+diffusion across the electrolyte/cathode interface.The as-fabricated oxygen defect-rich V2O5 on hierarchical porous carbon(ODVO@HPC)electrode exhibits high capacity robustness from 25 to20℃.Operating at-20℃,the ODVO@HPC delivers 191 mAh g-1 at 50 A g-1 and lasts for 50000 cycles at 10 A g-1,significantly enhancing the power density and lifespan under low-temperature environments in comparison to previous reports.Even with areal mass loading of-13 mg cm2,both coin cells and pouch batteries maintain excellent stability and areal capacities,realizing practical high-performance LT-ZIBs.展开更多
A hollow cathode is the electronic source and neutralizer of the Hall thruster and an ion thruster.When the orbit of an all-electric propulsion satellite changes from 100 km to 36 000 km, the backpressure changes by t...A hollow cathode is the electronic source and neutralizer of the Hall thruster and an ion thruster.When the orbit of an all-electric propulsion satellite changes from 100 km to 36 000 km, the backpressure changes by two to three orders of magnitude. In this paper, the influence of the backpressure on the discharge characteristics of the hollow cathode has been studied experimentally in the so-called diode configuration. With the increase in the backpressure, the anode voltage decreases gradually, and the amplitude of the current oscillation decreases significantly. Additionally, the plasma is relatively stable, the most probable ion energy and the width of the ion energy distribution reduces, and the electron distribution function inclines toward the Maxwell distribution under high backpressure. The analysis results show that the backpressure affects the gas ionization and the ionic acoustic turbulence, which also affects the discharge characteristics of the hollow cathode.展开更多
The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster plume.The characteristics of plasma in that region are complicated and strongly associated with the thrus...The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster plume.The characteristics of plasma in that region are complicated and strongly associated with the thruster working conditions and the cathode position.In this paper,a laboratory 100 W class magnetically shielded Hall thruster was coupled with a hollow cathode.Optical imaging and electrostatic probe were employed to monitor and scan the plasma plume.Plume characteristics in the coupling region in non-self-sustained mode and self-sustained mode were compared.Evolution of the coupling plume with the cathode position was studied.Experiments show that,when turning the thruster into self-sustained mode or moving the cathode further away axially,the discharge current can be reduced by 6.4–10.6%restraining the electron current and improving ionization.In particular,when the cathode is moved further,the electron conduction near the channel walls is suppressed.The electron current is reduced by 27.4%and the ion beam current is increased by 7%.Overall,this work shows that the working mode of the thruster and the position of the cathode greatly affect the coupling plasma plume.Both play an important role in improving the utilizations of propellant and current.展开更多
The excimer lasers have got rapidly growing applications in scientific researches and industries because of their high photon energy, short wavelengths, and the high average and peak output power. The applications of ...The excimer lasers have got rapidly growing applications in scientific researches and industries because of their high photon energy, short wavelengths, and the high average and peak output power. The applications of excimerlasers in scientific researches include pumping dye lasers, laser chemistry, multiphoton processes etc.; their applications in industries include laser isotope separation, laser annealing,展开更多
A high-voltage transverse pulsed nanosecond discharge with a slotted hollow cathode was found to be a source of high-energy （few kV） ribbon electron beams. Conditions for the formation and extinction of electron bea...A high-voltage transverse pulsed nanosecond discharge with a slotted hollow cathode was found to be a source of high-energy （few kV） ribbon electron beams. Conditions for the formation and extinction of electron beams were experimentally studied in discharges in helium at pressures of 1-100 Torr. It was found that interaction of fast electrons with a non-uniform electric field near the slotted cathode led to limitation of the magnitude of the discharge current. A physical model was developed to describe the discharge current self-limitation that was in satisfactory agreement with the experimental results. Some technical solutions that are expected to increase the upper current limits in transverse nanosecond discharge are discussed.展开更多
In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field- emission （FE） electron gun based on carbon nanotubes is researched. By feeding a high-frequency field...In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field- emission （FE） electron gun based on carbon nanotubes is researched. By feeding a high-frequency field between the cathode and the anode, the steady FE electron beam can be modulated in the electron gun. The optimal structure of the electron gun is discovered using 3D electromagnetism simulation software, and the FE electron gun is simulated by PIC simulation software. The results show that a broadband （74-114 GHz） modulation can be achieved by the electron gun with a rhombus channel, and the modulation amplitude of the beam current increases with the increases in the input power and the electrostatic field.展开更多
文摘The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La 2O 3 is dissociated, resulting in partial reduction of the lanthanum to LaO x(x <3/2). In addition, the lanthanum rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo La 2O 3 cathode.
基金the financial support from NSFC(21325419,21504095,and 51373181)the Chinese Academy of Science(XDB12030200,KJZD-EW-J01)。
文摘The modification mechanism of the water/alcohol cathode interlayer is one of the most complicated problems in the field of organic photovoltaics,which has not been clearly elucidated yet;this greatly restricts the further enhancement of the PCE for polymer solar cells.Herein,we clarified the different effects of PFN and its derivatives,namely,poly[(9,9-bis(3’-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)](PFN-Br) in modifying fullerene-free PSCs.It is found for the first time that doping on IT-4F by the amino group of PFN leads to the unfavorable charge accumulation,and hence,forms a dense layer of electronegative molecule due to the poor electron transport capacity of the non-fullerene acceptor IT-4F.The electronegative molecular layer can block the electron transfer from the active layer to the interlayer and cause serious charge recombination at the active layer/cathode interface.This mechanism could be verified by the ESR measurement and electron-only devices.By replacing PFN with PFN-Br,the excessive doping effect between the cathode interlayer and IT-4F is eliminated,by which the charge transport and collection can be greatly improved.As a result,a high PCE of 13.5%was achieved in the fullerene-free PSCs.
基金supported by the National Natural Science Foundation of China under Grant No.52072196,52002200,52102106,52202262,22379081,and 22379080Major Basic Research Program of the Natural Science Foundation of Shandong Province under Grant No.ZR2020ZD09+1 种基金the Natural Science Foundation of Shandong Province under Grant No.ZR2020QE063,ZR202108180009,ZR2023QE059the Postdoctoral Program in Qingdao under No.QDBSH20220202019。
文摘Rechargeable magnesium batteries(RMBs)hold promise for offering higher volumetric energy density and safety features,attracting increasing research interest as the next post lithium-ion batteries.Developing high performance cathode material by inducing multi-electron reaction process as well as maintaining structural stability is the key to the development and application of RMBs.Herein,multielectron reaction occurred in VS_(4)by simple W doping strategy.W doping induces valence of partial V as V^(2+)and V^(3+)in VS_(4)structure,and then stimulates electrochemical reaction involving multi-electrons in 0.5%W-V-S.The flower-like microsphere morphology as well as rich S vacancies is also modulated by W doping to neutralize structure change in such multi-electron reaction process.The fabricated 0.5%W-V-S delivers higher specific capacity(149.3 m A h g^(-1)at 50 m A g^(-1),which is 1.6 times higher than that of VS_(4)),superior rate capability(76 mA h g^(-1)at 1000 mA g^(-1)),and stable cycling performance(1500cycles with capacity retention ratio of 93.8%).Besides that,pesudocapaticance-like contribution analysis as well as galvanostatic intermittent titration technique(GITT)further confirms the enhanced Mg^(2+)storage kinetics during such multi-electron involved electrochemical reaction process.Such discovery provides new insights into the designing of multi-electron reaction process in cathode as well as neutralizing structural change during such reaction for realizing superior electrochemical performance in energy storage devices.
基金the National Key R&D Program of China(2021YFA1201503)National Natural Science Foundation of China(Nos.21972164,22279161,12264038,22309144)+7 种基金the Natural Science Foundation of Jiangsu Province(BK.20210130)China Postdoctoral Science Foundation(2023 M732561,2023 M731084)Innovative and Entrepreneurial Doctor in Jiangsu Province(JSSCBS20211428)J.W.and S.P.acknowledge the funding provided by the Alexander von Humboldt Foundation and the basic funding of the Helmholtz AssociationQ.Z.acknowledges the support of HZWTECH for providing computational facilitiesH.A.acknowledges the University of Hong Kong and the Hong Kong Quantum AI Lab Limited,AIR@Inno HK for supporting his fellowshipWe also thank Nano-X,Suzhou Institute of Nano-tech and Nano-bionics,Chinese Academy of Sciences for the material measurement analysisOpen Access funding enabled and organized by Projekt DEAL.
文摘Low-temperature zinc batteries(LT-ZIBs)based on aqueous electrolytes show great promise for practical applications owing to their natural resource abundance and low cost.However,they suffer from sluggish kinetics with elevated energy barriers due to the dissociation of bulky Zn(H2O)62+solvation structure and free Zn2+diffusion,resulting in unsatisfactory lifespan and performance.Herein,dissimilar to solvation shell tuning or layer spacing enlargement engineering,delocalized electrons in cathode through constructing intrinsic defect engineering is proposed to achieve a rapid electrocatalytic desolvation to obtain free Zn2+for insertion/extraction.As revealed by density functional theory calculations and interfacial spectroscopic characterizations,the intrinsic delocalized electron distribution propels the Zn(H2O)62+dissociation,forming a reversible interphase and facilitating Zn2+diffusion across the electrolyte/cathode interface.The as-fabricated oxygen defect-rich V2O5 on hierarchical porous carbon(ODVO@HPC)electrode exhibits high capacity robustness from 25 to20℃.Operating at-20℃,the ODVO@HPC delivers 191 mAh g-1 at 50 A g-1 and lasts for 50000 cycles at 10 A g-1,significantly enhancing the power density and lifespan under low-temperature environments in comparison to previous reports.Even with areal mass loading of-13 mg cm2,both coin cells and pouch batteries maintain excellent stability and areal capacities,realizing practical high-performance LT-ZIBs.
基金supported by National Natural Science Foundation of China (Nos. 61571166, 11775063, and 51736003
文摘A hollow cathode is the electronic source and neutralizer of the Hall thruster and an ion thruster.When the orbit of an all-electric propulsion satellite changes from 100 km to 36 000 km, the backpressure changes by two to three orders of magnitude. In this paper, the influence of the backpressure on the discharge characteristics of the hollow cathode has been studied experimentally in the so-called diode configuration. With the increase in the backpressure, the anode voltage decreases gradually, and the amplitude of the current oscillation decreases significantly. Additionally, the plasma is relatively stable, the most probable ion energy and the width of the ion energy distribution reduces, and the electron distribution function inclines toward the Maxwell distribution under high backpressure. The analysis results show that the backpressure affects the gas ionization and the ionic acoustic turbulence, which also affects the discharge characteristics of the hollow cathode.
基金supported by the National Natural Science Foundation of China(No.11872093)。
文摘The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster plume.The characteristics of plasma in that region are complicated and strongly associated with the thruster working conditions and the cathode position.In this paper,a laboratory 100 W class magnetically shielded Hall thruster was coupled with a hollow cathode.Optical imaging and electrostatic probe were employed to monitor and scan the plasma plume.Plume characteristics in the coupling region in non-self-sustained mode and self-sustained mode were compared.Evolution of the coupling plume with the cathode position was studied.Experiments show that,when turning the thruster into self-sustained mode or moving the cathode further away axially,the discharge current can be reduced by 6.4–10.6%restraining the electron current and improving ionization.In particular,when the cathode is moved further,the electron conduction near the channel walls is suppressed.The electron current is reduced by 27.4%and the ion beam current is increased by 7%.Overall,this work shows that the working mode of the thruster and the position of the cathode greatly affect the coupling plasma plume.Both play an important role in improving the utilizations of propellant and current.
文摘The excimer lasers have got rapidly growing applications in scientific researches and industries because of their high photon energy, short wavelengths, and the high average and peak output power. The applications of excimerlasers in scientific researches include pumping dye lasers, laser chemistry, multiphoton processes etc.; their applications in industries include laser isotope separation, laser annealing,
基金financially supported by the project part of the state assignment of the Ministry of Education and Science of Russia in scientific activities,project 3.1262.2014K
文摘A high-voltage transverse pulsed nanosecond discharge with a slotted hollow cathode was found to be a source of high-energy （few kV） ribbon electron beams. Conditions for the formation and extinction of electron beams were experimentally studied in discharges in helium at pressures of 1-100 Torr. It was found that interaction of fast electrons with a non-uniform electric field near the slotted cathode led to limitation of the magnitude of the discharge current. A physical model was developed to describe the discharge current self-limitation that was in satisfactory agreement with the experimental results. Some technical solutions that are expected to increase the upper current limits in transverse nanosecond discharge are discussed.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB933603)the National Natural Science Foundation of China(Grant Nos.U1134006 and 61101041)
文摘In order to develop miniaturized and integrated electron vacuum devices, the electron beam modulation in a field- emission （FE） electron gun based on carbon nanotubes is researched. By feeding a high-frequency field between the cathode and the anode, the steady FE electron beam can be modulated in the electron gun. The optimal structure of the electron gun is discovered using 3D electromagnetism simulation software, and the FE electron gun is simulated by PIC simulation software. The results show that a broadband （74-114 GHz） modulation can be achieved by the electron gun with a rhombus channel, and the modulation amplitude of the beam current increases with the increases in the input power and the electrostatic field.
