Methane,the primary constituent of natural gas,shale gas,and flammable ice,serves as a crucial carbon-based energy source and chemical feedstock.Traditional gas reserves are universally acknowledged as limited and non...Methane,the primary constituent of natural gas,shale gas,and flammable ice,serves as a crucial carbon-based energy source and chemical feedstock.Traditional gas reserves are universally acknowledged as limited and non-renewable resources over an extended timespan stretching from decades to millennia.Biomethane,with its unique renewable properties,showcases remarkable development potential and presents a compelling supplement and even alternative for fossil fuel.Although catalytic hydrothermal processes appear as promising valorization routes to transfer biomass to sustainable methane,the safety and supply source of high-pressure hydrogen remain key factors restricting the widespread application.Herein,a catalytic approach without an external hydrogen source was developed to transform waste biomass resources into CH_(4)under the Ni-Mo catalyst.The total carbon yield of gas products reached up to 92.2%,of which the yield of methane and C2–C4 hydrocarbons were 44.9%and 3.0%,respectively.And it’s calculated that approximately 343.6 liters of CH_(4)could potentially be generated from 1 kilogram of raw biomass.Ni-based catalysts exhibited the robust activity in cleaving C–C and C–O bonds.And the introduction of an appropriate amount of molybdenum significantly enhanced catalytic performance of reforming and subsequent methanation reaction,likely due to the high adsorption capacity of highly dispersed Ni-Mo catalysts for carbon monoxide and hydrogen molecules,facilitating the methanation reaction.The pathway of catalytic methane production might be inferred that CO,H_(2)and a large number of oxygen-containing intermediates were formed via decarbonylation,dehydrogenation,and retro-aldol condensation reaction under hydrothermal condition.These intermediates then underwent the reforming reaction to generate H_(2)and CO_(2),ultimately forming CH_(4)through the methanation reaction.展开更多
The developments of hydrogen sources stand at the forefront of asymmetric reduction. In contrast to the well-studied alcohols as hydrogen sources via β-hydride elimination, the direct utilization of the proton of alc...The developments of hydrogen sources stand at the forefront of asymmetric reduction. In contrast to the well-studied alcohols as hydrogen sources via β-hydride elimination, the direct utilization of the proton of alcohols as a hydrogen source for activatormediated asymmetric reduction is rarely explored. Herein we report the proton of alcohols as a hydrogen source in diboronmediated palladium-catalyzed asymmetric transfer hydrogenation of 1,3-diketones and indoles, providing a series of chiral β-hydroxy ketones and indolines with excellent yields and enantioselectivities. This strategy would be useful for the synthesis of chiral deuterium-labelled compounds due to the ready availability of deuterium-labelled alcohols. Mechanistic investigations and DFT calculations revealed that active chiral Pd-H species was generated from the proton of alcohols by activating of tetrahydroxydiboron, hydrogen transfer was the rate-determining step, and the reaction preferred Pd(0)-catalyzed mechanism.展开更多
In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Ga...In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×10^(17)m^(-3)in the case without the magnetic shield,and the value increases to 9.4×10^(17)m^(-3)when the magnetic shield is introduced.展开更多
A three-dimensional fluid model is developed to investigate the radio-frequency inductively coupled H2 plasma in a reactor with a rectangular expansion chamber and a cylindrical driver chamber,for neutral beam injecti...A three-dimensional fluid model is developed to investigate the radio-frequency inductively coupled H2 plasma in a reactor with a rectangular expansion chamber and a cylindrical driver chamber,for neutral beam injection system in CFETR.In this model,the electron effective collision frequency and the ion mobility at high E-fields are employed,for accurate simulation of discharges at low pressures(0.3 Pa-2 Pa)and high powers(40 kW-100 kW).The results indicate that when the high E-field ion mobility is taken into account,the electron density is about four times higher than the value in the low E-field case.In addition,the influences of the magnetic field,pressure and power on the electron density and electron temperature are demonstrated.It is found that the electron density and electron temperature in the xz-plane along permanent magnet side become much more asymmetric when magnetic field enhances.However,the plasma parameters in the yz-plane without permanent magnet side are symmetric no matter the magnetic field is applied or not.Besides,the maximum of the electron density first increases and then decreases with magnetic field,while the electron temperature at the bottom of the expansion region first decreases and then almost keeps constant.As the pressure increases from 0.3 Pa to 2 Pa,the electron density becomes higher,with the maximum moving upwards to the driver region,and the symmetry of the electron temperature in the xz-plane becomes much better.As power increases,the electron density rises,whereas the spatial distribution is similar.It can be summarized that the magnetic field and gas pressure have great influence on the symmetry of the plasma parameters,while the power only has little effect.展开更多
A radio-frequency(RF) inductively coupled negative hydrogen ion source(NHIS) has been adopted in the China Fusion Engineering Test Reactor(CFETR) to generate negative hydrogen ions.By incorporating the level-lumping m...A radio-frequency(RF) inductively coupled negative hydrogen ion source(NHIS) has been adopted in the China Fusion Engineering Test Reactor(CFETR) to generate negative hydrogen ions.By incorporating the level-lumping method into a three-dimensional fluid model,the volume production and transportation of H^(-) in the NHIS,which consists of a cylindrical driver region and a rectangular expansion chamber,are investigated self-consistently at a large input power(40 k W) and different pressures(0.3–2.0 Pa).The results indicate that with the increase of pressure,the H^(-) density at the bottom of the expansion region first increases and then decreases.In addition,the effect of the magnetic filter is examined.It is noteworthy that a significant increase in the H^(-) density is observed when the magnetic filter is introduced.As the permanent magnets move towards the driver region,the H^(-) density decreases monotonically and the asymmetry is enhanced.This study contributes to the understanding of H-distribution under various conditions and facilitates the optimization of volume production of negative hydrogen ions in the NHIS.展开更多
A room-temperature electrochemical strategy for hydrogenation(deuteration)and reverse dehydrogenation of N-heterocycles over a bifunctional MoNi_(4)electrode is developed,which includes the hydrogenation of quinoxalin...A room-temperature electrochemical strategy for hydrogenation(deuteration)and reverse dehydrogenation of N-heterocycles over a bifunctional MoNi_(4)electrode is developed,which includes the hydrogenation of quinoxaline using H2O as the hydrogen source with 80%Faradaic efficiency and the reverse dehydrogenation of hydrogen-rich 1,2,3,4-tetrahydroquinoxaline with up to 99%yield and selectivity.The in situ generated active hydrogen atom(H^(*))is plausibly involved in the hydrogenation of quinoxaline,where a consecutive hydrogen radical coupled electron transfer pathway is proposed.Notably,the MoNi_(4)alloy exhibits efficient quinoxaline hydrogenation at an overpotential of only 50 mV,owing to its superior water dissociation ability to provide H^(*)in alkaline media.In situ Raman tests indicate that the Ni^(Ⅱ)/Ni^(Ⅲ)redox couple can promote the dehydrogenation process,representing a promising anodic alternative to low-value oxygen evolution.Impressively,electrocatalytic deuteration is easily achieved with up to 99%deuteration ratios using D2O.This method is capable of producing a series of functionalized hydrogenated and deuterated quinoxalines.展开更多
Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion sour...Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.展开更多
It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of ...It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of water-using networks are extended to synthesis of hydrogen networks with multiple contaminants. In the design procedure, the precedence of processes is determined by the values of concentration potential of demands.The usage of complementary source pair(s) to reduce utility consumption is investigated. Three case studies are presented to illustrate the effectiveness of the method. It is shown that the design procedure has clear engineering meaning.展开更多
Transfer hydrogenation(TH)has become the new frontier of hydrogenation science owing to the use of non-H2 hydrogen sources which are safer and easier handling for constructing various hydrogenated products.As for hete...Transfer hydrogenation(TH)has become the new frontier of hydrogenation science owing to the use of non-H2 hydrogen sources which are safer and easier handling for constructing various hydrogenated products.As for heterogeneous catalysts applied for TH which take advantages of convenient separation and recycling,single-atom catalysts(SACs)are attractive alternatives because of their maximum atom utilization,well-defined active sites and tunable local atomic structure.Recent literature has manifested the good performance of SACs for TH,gaining attention both from academia and industry.In this perspective,we review TH achieved by SACs according to classified hydrogen sources and provide a comprehensive understanding of the relationship between their structural characters and performance for TH.In addition,corresponding synthetic strategies of SACs are also demonstrated to reveal their roles in forming the featured structures.The remained challenges and potential opportunities in this field are also discussed in the end.This review will guide the design of better-performing SACs for TH and give an impetus to the development of green and cost-effective hydrogenation technology.展开更多
A straightforward electrochemical reduction of benzo[b]thiophene 1,1-dioxides with HFIP as the hydrogen donor has been reported in an undivided cell under metal-free conditions.Moreover,the tolerance of various functi...A straightforward electrochemical reduction of benzo[b]thiophene 1,1-dioxides with HFIP as the hydrogen donor has been reported in an undivided cell under metal-free conditions.Moreover,the tolerance of various functional groups and scaled-up experiments showed the practicability and potential applications of this methodology.展开更多
We present an extended update on the status of a particle-in-cellwithMonte Carlo collisions(PIC-MCC)gun code developed at LosAlamos for the study of surfaceconverter H−ion sources.The programis fully kinetic.Some of t...We present an extended update on the status of a particle-in-cellwithMonte Carlo collisions(PIC-MCC)gun code developed at LosAlamos for the study of surfaceconverter H−ion sources.The programis fully kinetic.Some of the program’s features include:solution of arbitrary electrostatic and magnetostatic fields in an axisymmetric(r,z)geometry to describe the self-consistent time evolution of a plasma;simulation of a multi-species(e^(−),H^(+),H^(+)_(2),H^(+)_(3),H^(−))plasma discharge from a neutral hydrogen gas and filament-originated seed electrons;full 2-dimensional(r,z)3-velocity(v_(r),v_(z),vφ)dynamics for all species;detailed collision physics between charged particles and neutrals and the ability to represent multiple smooth(not stair-stepped)electrodes of arbitrary shape and voltage whose surfaces may be secondary-particle emitters(H^(−)and e^(−)).The status of this development is discussed in terms of its physics content and current implementation details.展开更多
A quartz-chamber 2.45 GHz electron cyclotron resonance ion source(ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 m A hydro...A quartz-chamber 2.45 GHz electron cyclotron resonance ion source(ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 m A hydrogen ion beam at 50 k V with a duty factor of 10%. The root-mean-square(RMS) emittance of this beam is less than 0.12π mm mrad. In our initial work,the electron temperature and electron density inside the plasma chamber had been measured with the line intensity ratio of noble gases. Based on these results, the atomic and molecular emission spectra of hydrogen were applied to determine the dissociation degree of hydrogen and the vibrational temperature of hydrogen molecules in the ground state, respectively. Measurements were performed at gas pressures from 4×10^(-4) to 1×10^(-3) Pa and at input peak RF power ranging from 1000 to 1800 W. The dissociation degree of hydrogen in the range of 0.5%-10% and the vibrational temperature of hydrogen molecules in the ground state in the range of 3500-8500 K were obtained. The plasma processes inside this ECRIS chamber were discussed based on these results.展开更多
The electrolysis of water to produce hydrogen is an important technique to replace traditional fossil fuel-based hydrogen production.This method efficiently converts electrical energy into chemical energy,it is ostens...The electrolysis of water to produce hydrogen is an important technique to replace traditional fossil fuel-based hydrogen production.This method efficiently converts electrical energy into chemical energy,it is ostensibly a promising candidate for addressing the energy crisis.Significant effort has been devoted to developing efficient electrocatalysts for water electrolysis.The exploration of suitable catalytic materials for the hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and other bifunctional electrocatalytic reactions is crucial.Transition metal selenides(TMSes)have emerged as potential HER and OER electrocatalysts because of their unique electronic structures,which are beneficial for charge transfer,tuneable bandgaps,distinctive morphologies,and low-cost.This review discusses the mechanisms and performance comparisons of TMSes in overall water splitting under various pH conditions.From an industrial and commercial perspective,the catalytic performance of TMSes for the HER and OER is not ideal.Methods for preparing electrocatalytic materials and optimizing materials for overall water decomposition and modulation mechanisms have been introduced to improve electrocatalytic performance,such as element doping,carbon composites,bimetallic systems,morphology control,and heterogeneous interface engineering.Finally,the challenges and prospects of TMSes were discussed.展开更多
文摘Methane,the primary constituent of natural gas,shale gas,and flammable ice,serves as a crucial carbon-based energy source and chemical feedstock.Traditional gas reserves are universally acknowledged as limited and non-renewable resources over an extended timespan stretching from decades to millennia.Biomethane,with its unique renewable properties,showcases remarkable development potential and presents a compelling supplement and even alternative for fossil fuel.Although catalytic hydrothermal processes appear as promising valorization routes to transfer biomass to sustainable methane,the safety and supply source of high-pressure hydrogen remain key factors restricting the widespread application.Herein,a catalytic approach without an external hydrogen source was developed to transform waste biomass resources into CH_(4)under the Ni-Mo catalyst.The total carbon yield of gas products reached up to 92.2%,of which the yield of methane and C2–C4 hydrocarbons were 44.9%and 3.0%,respectively.And it’s calculated that approximately 343.6 liters of CH_(4)could potentially be generated from 1 kilogram of raw biomass.Ni-based catalysts exhibited the robust activity in cleaving C–C and C–O bonds.And the introduction of an appropriate amount of molybdenum significantly enhanced catalytic performance of reforming and subsequent methanation reaction,likely due to the high adsorption capacity of highly dispersed Ni-Mo catalysts for carbon monoxide and hydrogen molecules,facilitating the methanation reaction.The pathway of catalytic methane production might be inferred that CO,H_(2)and a large number of oxygen-containing intermediates were formed via decarbonylation,dehydrogenation,and retro-aldol condensation reaction under hydrothermal condition.These intermediates then underwent the reforming reaction to generate H_(2)and CO_(2),ultimately forming CH_(4)through the methanation reaction.
基金the National Natural Science Foundation of China(21901239,21532006)the Strategic Priority Program of Chinese Academy of Sciences(XDB17020300,QYZDJ-SSW-SLH035)。
文摘The developments of hydrogen sources stand at the forefront of asymmetric reduction. In contrast to the well-studied alcohols as hydrogen sources via β-hydride elimination, the direct utilization of the proton of alcohols as a hydrogen source for activatormediated asymmetric reduction is rarely explored. Herein we report the proton of alcohols as a hydrogen source in diboronmediated palladium-catalyzed asymmetric transfer hydrogenation of 1,3-diketones and indoles, providing a series of chiral β-hydroxy ketones and indolines with excellent yields and enantioselectivities. This strategy would be useful for the synthesis of chiral deuterium-labelled compounds due to the ready availability of deuterium-labelled alcohols. Mechanistic investigations and DFT calculations revealed that active chiral Pd-H species was generated from the proton of alcohols by activating of tetrahydroxydiboron, hydrogen transfer was the rate-determining step, and the reaction preferred Pd(0)-catalyzed mechanism.
基金supported by the National Key R&D Program of China(No.2017YFE0300106)National Natural Science Foundation of China(No.12075049)the Fundamental Research Funds for the Central Universities(Nos.DUT20LAB201 and DUT21LAB110)。
文摘In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×10^(17)m^(-3)in the case without the magnetic shield,and the value increases to 9.4×10^(17)m^(-3)when the magnetic shield is introduced.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFE0300106)the National Natural Science Foundation of China(Grant No.12075049)the Fundamental Research Funds for the Central Universities,China(Grant Nos.DUT20LAB201 and DUT21LAB110).
文摘A three-dimensional fluid model is developed to investigate the radio-frequency inductively coupled H2 plasma in a reactor with a rectangular expansion chamber and a cylindrical driver chamber,for neutral beam injection system in CFETR.In this model,the electron effective collision frequency and the ion mobility at high E-fields are employed,for accurate simulation of discharges at low pressures(0.3 Pa-2 Pa)and high powers(40 kW-100 kW).The results indicate that when the high E-field ion mobility is taken into account,the electron density is about four times higher than the value in the low E-field case.In addition,the influences of the magnetic field,pressure and power on the electron density and electron temperature are demonstrated.It is found that the electron density and electron temperature in the xz-plane along permanent magnet side become much more asymmetric when magnetic field enhances.However,the plasma parameters in the yz-plane without permanent magnet side are symmetric no matter the magnetic field is applied or not.Besides,the maximum of the electron density first increases and then decreases with magnetic field,while the electron temperature at the bottom of the expansion region first decreases and then almost keeps constant.As the pressure increases from 0.3 Pa to 2 Pa,the electron density becomes higher,with the maximum moving upwards to the driver region,and the symmetry of the electron temperature in the xz-plane becomes much better.As power increases,the electron density rises,whereas the spatial distribution is similar.It can be summarized that the magnetic field and gas pressure have great influence on the symmetry of the plasma parameters,while the power only has little effect.
基金supported by the National Key R&D Program of China (No. 2017YFE0300106)National Natural Science Foundation of China (Nos. 11935005 and 12075049)the Fundamental Research Funds for the Central Universities(Nos. DUT21TD104 and DUT21LAB110)。
文摘A radio-frequency(RF) inductively coupled negative hydrogen ion source(NHIS) has been adopted in the China Fusion Engineering Test Reactor(CFETR) to generate negative hydrogen ions.By incorporating the level-lumping method into a three-dimensional fluid model,the volume production and transportation of H^(-) in the NHIS,which consists of a cylindrical driver region and a rectangular expansion chamber,are investigated self-consistently at a large input power(40 k W) and different pressures(0.3–2.0 Pa).The results indicate that with the increase of pressure,the H^(-) density at the bottom of the expansion region first increases and then decreases.In addition,the effect of the magnetic filter is examined.It is noteworthy that a significant increase in the H^(-) density is observed when the magnetic filter is introduced.As the permanent magnets move towards the driver region,the H^(-) density decreases monotonically and the asymmetry is enhanced.This study contributes to the understanding of H-distribution under various conditions and facilitates the optimization of volume production of negative hydrogen ions in the NHIS.
文摘A room-temperature electrochemical strategy for hydrogenation(deuteration)and reverse dehydrogenation of N-heterocycles over a bifunctional MoNi_(4)electrode is developed,which includes the hydrogenation of quinoxaline using H2O as the hydrogen source with 80%Faradaic efficiency and the reverse dehydrogenation of hydrogen-rich 1,2,3,4-tetrahydroquinoxaline with up to 99%yield and selectivity.The in situ generated active hydrogen atom(H^(*))is plausibly involved in the hydrogenation of quinoxaline,where a consecutive hydrogen radical coupled electron transfer pathway is proposed.Notably,the MoNi_(4)alloy exhibits efficient quinoxaline hydrogenation at an overpotential of only 50 mV,owing to its superior water dissociation ability to provide H^(*)in alkaline media.In situ Raman tests indicate that the Ni^(Ⅱ)/Ni^(Ⅲ)redox couple can promote the dehydrogenation process,representing a promising anodic alternative to low-value oxygen evolution.Impressively,electrocatalytic deuteration is easily achieved with up to 99%deuteration ratios using D2O.This method is capable of producing a series of functionalized hydrogenated and deuterated quinoxalines.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11175009 and 11575013)
文摘Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.
基金Supported by the National Natural Science Foundation of China(21176057)the National Basic Research Program of China(2012CB720305)the State Key Laboratory of Chemical Engineering(Open Research Project Skloche-K-2011-04)
文摘It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of water-using networks are extended to synthesis of hydrogen networks with multiple contaminants. In the design procedure, the precedence of processes is determined by the values of concentration potential of demands.The usage of complementary source pair(s) to reduce utility consumption is investigated. Three case studies are presented to illustrate the effectiveness of the method. It is shown that the design procedure has clear engineering meaning.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY24B010003)the National Natural Science Foundation of China(No.22102119),and the WenZhou(No.2024R3001).
文摘Transfer hydrogenation(TH)has become the new frontier of hydrogenation science owing to the use of non-H2 hydrogen sources which are safer and easier handling for constructing various hydrogenated products.As for heterogeneous catalysts applied for TH which take advantages of convenient separation and recycling,single-atom catalysts(SACs)are attractive alternatives because of their maximum atom utilization,well-defined active sites and tunable local atomic structure.Recent literature has manifested the good performance of SACs for TH,gaining attention both from academia and industry.In this perspective,we review TH achieved by SACs according to classified hydrogen sources and provide a comprehensive understanding of the relationship between their structural characters and performance for TH.In addition,corresponding synthetic strategies of SACs are also demonstrated to reveal their roles in forming the featured structures.The remained challenges and potential opportunities in this field are also discussed in the end.This review will guide the design of better-performing SACs for TH and give an impetus to the development of green and cost-effective hydrogenation technology.
基金supported by the National Natural Science Foundation of China(21801152 and 21572110)We thank the Youth Innovation Science and Technology Plan of Colleges and Universities in Shandong Province(2021KJ076).
文摘A straightforward electrochemical reduction of benzo[b]thiophene 1,1-dioxides with HFIP as the hydrogen donor has been reported in an undivided cell under metal-free conditions.Moreover,the tolerance of various functional groups and scaled-up experiments showed the practicability and potential applications of this methodology.
基金This research is supported by the US Department of Energy through contract DE-AC52-06NA25396.
文摘We present an extended update on the status of a particle-in-cellwithMonte Carlo collisions(PIC-MCC)gun code developed at LosAlamos for the study of surfaceconverter H−ion sources.The programis fully kinetic.Some of the program’s features include:solution of arbitrary electrostatic and magnetostatic fields in an axisymmetric(r,z)geometry to describe the self-consistent time evolution of a plasma;simulation of a multi-species(e^(−),H^(+),H^(+)_(2),H^(+)_(3),H^(−))plasma discharge from a neutral hydrogen gas and filament-originated seed electrons;full 2-dimensional(r,z)3-velocity(v_(r),v_(z),vφ)dynamics for all species;detailed collision physics between charged particles and neutrals and the ability to represent multiple smooth(not stair-stepped)electrodes of arbitrary shape and voltage whose surfaces may be secondary-particle emitters(H^(−)and e^(−)).The status of this development is discussed in terms of its physics content and current implementation details.
基金supported by the National Natural Science Foundation of China(Grant Nos.11775007,and 11575013)The support from State Key Laboratory of Nuclear Physics and Technology,Peking University is appreciated
文摘A quartz-chamber 2.45 GHz electron cyclotron resonance ion source(ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 m A hydrogen ion beam at 50 k V with a duty factor of 10%. The root-mean-square(RMS) emittance of this beam is less than 0.12π mm mrad. In our initial work,the electron temperature and electron density inside the plasma chamber had been measured with the line intensity ratio of noble gases. Based on these results, the atomic and molecular emission spectra of hydrogen were applied to determine the dissociation degree of hydrogen and the vibrational temperature of hydrogen molecules in the ground state, respectively. Measurements were performed at gas pressures from 4×10^(-4) to 1×10^(-3) Pa and at input peak RF power ranging from 1000 to 1800 W. The dissociation degree of hydrogen in the range of 0.5%-10% and the vibrational temperature of hydrogen molecules in the ground state in the range of 3500-8500 K were obtained. The plasma processes inside this ECRIS chamber were discussed based on these results.
基金financially supported by the National Natural Science Foundation of China(No.U2002213)Tianshan Innovation Team Plan of Xinjiang Uygur Autonomous Region(No.2023D14002)+3 种基金Open Foundation of Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials(No.2022GXYSOF10)Open Fund of the Hubei Longzhong Laboratory(No.2022KF07)Science Foundation of Donghai Laboratory(No.DH-2022KF0314)Double-First Class University Plan(No.C176220100042).
文摘The electrolysis of water to produce hydrogen is an important technique to replace traditional fossil fuel-based hydrogen production.This method efficiently converts electrical energy into chemical energy,it is ostensibly a promising candidate for addressing the energy crisis.Significant effort has been devoted to developing efficient electrocatalysts for water electrolysis.The exploration of suitable catalytic materials for the hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and other bifunctional electrocatalytic reactions is crucial.Transition metal selenides(TMSes)have emerged as potential HER and OER electrocatalysts because of their unique electronic structures,which are beneficial for charge transfer,tuneable bandgaps,distinctive morphologies,and low-cost.This review discusses the mechanisms and performance comparisons of TMSes in overall water splitting under various pH conditions.From an industrial and commercial perspective,the catalytic performance of TMSes for the HER and OER is not ideal.Methods for preparing electrocatalytic materials and optimizing materials for overall water decomposition and modulation mechanisms have been introduced to improve electrocatalytic performance,such as element doping,carbon composites,bimetallic systems,morphology control,and heterogeneous interface engineering.Finally,the challenges and prospects of TMSes were discussed.
