We first introduce the concepts of absolutely E-pure modules and E-pure split modules. Then, we characterize the IF rings in terms of absolutely E-pure modules. The E-pure split modules are also characterized.
Addressing inadequate OH^(*)adsorption in Ru Co alloy catalysts is crucial for boosting intermediate coverage and redirecting the water-splitting pathway.Herein,the adaptive P sites were strategically incorporated to ...Addressing inadequate OH^(*)adsorption in Ru Co alloy catalysts is crucial for boosting intermediate coverage and redirecting the water-splitting pathway.Herein,the adaptive P sites were strategically incorporated to overcome the aforementioned challenge.The P sites,as potent OH^(*)adsorption centers,synergize with Co sites to promote water dissociation and enrich surrounding Ru sites with H*intermediates,thus triggering the Volmer-Tafel route for hydrogen evolution reaction(HER).Besides,during the oxygen evolution reaction(OER),the surface of P-Ru Co was reconstructed into Ru-doped Co OOH with anchored PO_(4)^(3-).These PO_(4)^(3-)not only circumvent the intrinsic OH^(*)adsorption limitations of Ru-Co OOH in the adsorbate evolution mechanism(AEM)by rerouting to a more expeditious lattice oxygen oxidation mechanism(LOM)but also improve the coverage of key oxygen-containing intermediates,significantly accelerating OER kinetics.Consequently,the P-Ru Co demonstrates exceptional bifunctional performance,with overpotentials of 29 m V for HER and 222 m V for OER at 10 m A cm^(-2).Remarkably,the mass activities of PRu Co for HER(5.48 A mg^(-1))and OER(2.13 A mg^(-1))are 6.2 and 11.2 times higher than those of its commercial counterparts(Ru/C for HER and RuO_(2)for OER),respectively.When integrated into an anionexchange-membrane electrolyzer,this catalyst achieves ampere-level current densities of 1.32 A cm^(-2)for water electrolysis and 1.23 A cm^(-2)for seawater electrolysis at 2.1 V,with a 500-h durability.展开更多
Constructing heterointerface engineering has becoming an effective and general strategy for developing highly efficient and durable nonnoble electrocatalysts for catalyzing both hydrogen evolution reaction(HER)and oxy...Constructing heterointerface engineering has becoming an effective and general strategy for developing highly efficient and durable nonnoble electrocatalysts for catalyzing both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this work,we synthesized a self-supporting heterogeneous NiSe@Co_(0.85)Se/NF electrocatalyst using a facile in situ selenization of transition metal precursors that coated on the nickel foam(NF)in polyol solution.The NF was used as both conductive substrate and nickel source,ensuring superior electronic conductivity for catalyzing.The NiSe@-Co_(0.85)Se/NF exhibited remarkable bifunctional electrocatalytic activities with HER overpotential of 168 mV and OER overpotential of 258 mV to achieve 10 mA·cm-2.The water splitting system using NiSe@Co_(0.85)Se/NF as both anode and cathode electrodes achieved a current density of 10 mA·cm^(-2) at 1.61 V with nearly 100% faradaic efficiency and impressively long-term stability.The efficient bifunctional catalytic performance of NiSe@-Co_(0.85)Se/NF should be attributed to the electronic modulation and synergistic effect between NiSe and Co_(0.85)Se,the intrinsic metallic conductivity and the enlarged active sites exposure.This work provides a facile method for developing heterogeneous bifunctional catalysts for advanced electrochemical energy conversion technologies.展开更多
Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficienc...Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficiency of their half reactions including hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),electrocatalysts are usually essential to reduce their kinetic energy barriers.Electrospun nanomaterials possess a unique one‐dimensional structure for outstanding electron and mass transportation,large specific surface area,and the possibilities of flexibility with the porous feature,which are good candidates as efficient electrocatalysts for water splitting.In this review,we focus on the recent research progress on the electrospun nanomaterials‐based electrocatalysts for HER,OER,and overall water splitting reaction.Specifically,the insights of the influence of the electronic modulation and interface engineering of these electrocatalysts on their electrocatalytic activities will be deeply discussed and highlighted.Furthermore,the challenges and development opportunities of the electrospun nanomaterials‐based electrocatalysts for water splitting are featured.Based on the achievements of the significantly enhanced performance from the electronic modulation and interface engineering of these electrocatalysts,full utilization of these materials for practical energy conversion is anticipated.展开更多
Designing and synthesizing cost-effective bifunctional catalysts for overall alkaline water/seawater splitting is still a huge challenge for hydrogen production.Herein,Co/Ni/Fe/Mn based-amorphous high-entropy phosphox...Designing and synthesizing cost-effective bifunctional catalysts for overall alkaline water/seawater splitting is still a huge challenge for hydrogen production.Herein,Co/Ni/Fe/Mn based-amorphous high-entropy phosphoxide self-standing electrode(CNFMPO)is synthesized by the facile and fast electrodeposition method.CNFMPO exhibits excellent bifunctional electrocatalytic performances on alkaline water/seawater electrolysis.The hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)overpotentials of CNFMPO in alkaline water/seawater are as low as 43/73 and 252/282 mV to reach a current density of 10 mA cm^(-2),respectively.Additionally,two-electrode electrolyzers with CNFMPO||CNFMPO successfully achieve the current density of 10 mA cm^(-2) at low voltages of 1.54 and 1.56 V for overall alkaline water/seawater splitting,respectively.CNFMPO exhibits satisfactory long-term stability on overall alkaline water/seawater splitting for the surface reconstruction into active metal hydroxide/(oxy)hydroxide,phosphite,and phosphate.Moreover,no hypochlorite is detected during seawater electrolysis for the beneficial chlorite oxidation inhibition of the reconstructed phosphite and phosphate.The excellent catalytic performances of CNFMPO are due to the unique amorphous structure,multi-component synergistic effect,beneficial electronic structure modulation,and surface reconstruction during the catalytic reaction process.Therefore,CNFMPO has shown potential promotion to the development of the water/seawater splitting industry as a promising substituent for noble-metal electrocatalysts.This work provides new insights into the design of efficient bifunctional catalysts for overall water/seawater splitting.展开更多
针对多雷达辐射源脉冲交错背景下,线性调频(Linear Frequency Modulation,LFM)信号低信噪比导致的脉冲分裂带来原始信号参数难以估计的问题,本文提出了基于深度神经网络和直方图统计的LFM信号两阶段提取与参数估计方法。首先利用双向长...针对多雷达辐射源脉冲交错背景下,线性调频(Linear Frequency Modulation,LFM)信号低信噪比导致的脉冲分裂带来原始信号参数难以估计的问题,本文提出了基于深度神经网络和直方图统计的LFM信号两阶段提取与参数估计方法。首先利用双向长短时记忆网络挖掘原始脉冲流中LFM信号与非LFM信号的调制模式差异并进行分类;其次通过序列调频斜率直方图寻找LFM信号分裂脉冲序列间隐含的原始信号调频斜率信息,提取不同调频斜率的LFM信号脉冲子序列;最后在每个子序列中分别估计原始信号的参数。仿真实验结果表明,相较于传统的序列差值直方图算法和循环神经网络分选方法,本文所提方法能够更准确地提取出LFM脉冲信号,并得到较为精确的参数估计结果。展开更多
This paper demonstrates the intensity modulation characters of orthogonally polarized HeNe lasers with different optical feedback level generated by the variable reflectivity of external reflector. The modulation dept...This paper demonstrates the intensity modulation characters of orthogonally polarized HeNe lasers with different optical feedback level generated by the variable reflectivity of external reflector. The modulation depths of the orthogonally polarized frequencies are increased when the optical feedback level becomes strong. It also observes that the modulation amplitudes are different for different external cavity length. Based on the vectorial extension of Lamb＇s semi-classical theory, it finds that the calculations are consistent with the experimental results.展开更多
We compare the transport properties of electrons in monolayer graphene by modulating the Fermi velocity inside the barrier. A critical transmission angle is found only when the Fermi velocity in the barriers is larger...We compare the transport properties of electrons in monolayer graphene by modulating the Fermi velocity inside the barrier. A critical transmission angle is found only when the Fermi velocity in the barriers is larger than the one outside the barriers. It is shown that the transmission exhibits periodicity with the incident angle below the critical transmission angle, and attenuates exponentially in the opposite situation. For both situations, peak splitting occurs in the transmission as the number of the velocity barriers increases, and the characteristics of the transmission suggest an interesting application of an excellent band-pass filter. The dependence of the conductance on the Fermi energy through an identical velocity- modulation structure differs wildly with different Fermi velocities of the barrier. The counterpart of the peak splitting is the sharp oscillations in the conductance profile. Furthermore, some oscillations for the multiple barriers are so sharp that the structure may be used as an excellent sensor.展开更多
Herein,we report bifunctional molybdenum-doped nickel sulfide on nickel foam(Mo-NiS_(x)/NF)for magnetic field-enhanced overall water splitting under alkaline conditions.Proper doping of Mo can lead to optimization of ...Herein,we report bifunctional molybdenum-doped nickel sulfide on nickel foam(Mo-NiS_(x)/NF)for magnetic field-enhanced overall water splitting under alkaline conditions.Proper doping of Mo can lead to optimization of the electronic structure of NiS_(x),which accelerates the dissociation of H2O and the adsorption of OH−in the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)processes,respectively.In addition,the magnetically active Mo-NiS_(x)/NF can further enhance the HER and OER activity under an applied magnetic field due to the magnetoresistance effect and the ferromagnetic(FM)exchange-field penetration effect.As a result,Mo-NiS_(x)/NF requires low overpotentials of 307 mV at 50mA cm^(−2)(for OER)and 136 mV at 10mA cm^(−2)(for HER)under a magnetic field of 10000 G.Furthermore,the electrolytic cell constructed by the bifunctional Mo-NiS_(x)/NFs as both the cathode and the anode shows a low cell voltage of 1.594 V at 10 mA cm^(−2)with optimal stability over 60 h under the magnetic field.Simultaneous enhancement of the HER and OER processes by an external magnetic field through rational design of electrocatalysts might be promising for overall water splitting applications.展开更多
We report the experimental results on measuring the isotope shifts and hyperfine splittings of all ytterbium isotopes for a 399-nm transition by using a quite simple and novel method. It benefits from the advantages o...We report the experimental results on measuring the isotope shifts and hyperfine splittings of all ytterbium isotopes for a 399-nm transition by using a quite simple and novel method. It benefits from the advantages of the modulation transfer spectroscopy in an ytterbium hollow cathode lamp and the Doppler-free spectroscopy in a collimated ytterbium atomic beam. The key technique in this experiment is simultaneously measuring the frequency separations of the two spectra twice, and the separation difference between two measurements is solely determined by the well-defined frequency of an acousto-optics modulator. Compared with the most of previously reported experimental results, ours are more accurate and completed, which will provide the useful information for developing a more accurate theoretical model to describe the interaction inside an ytterbium atom.展开更多
After defining Hom(chi (A), eta (B)) and chi (A) circle times eta (B) in the fuzzy modular category Fm, the sufficient conditions of the existence for exact Hom functors Hom(delta (M),), and Hom(, delta (M)), as well ...After defining Hom(chi (A), eta (B)) and chi (A) circle times eta (B) in the fuzzy modular category Fm, the sufficient conditions of the existence for exact Hom functors Hom(delta (M),), and Hom(, delta (M)), as well as exact Tensor functors delta (M)circle times and circle times delta (M) are given in this paper. Finally the weak isomorphisms relations between Horn functors and Tensor functors are displayed.展开更多
Let F be a locally defined formation consisting of locally solvable groups, G a hyper-（ cyclic or finite） locally solvable group and A a noetherian ZG-module with all irreducible ZG-factors being finite. The followi...Let F be a locally defined formation consisting of locally solvable groups, G a hyper-（ cyclic or finite） locally solvable group and A a noetherian ZG-module with all irreducible ZG-factors being finite. The following conclusion is obtained： if G∈F, f（ ∞ ） include f（p）, f（p） ≠φ for each p∈π, and A has no nonzero F central ZG- images, then any extension E of A by G splits conjugately over A, and A has no nonzero F central ZG-factors.展开更多
文摘We first introduce the concepts of absolutely E-pure modules and E-pure split modules. Then, we characterize the IF rings in terms of absolutely E-pure modules. The E-pure split modules are also characterized.
基金supported by the National Natural Science Foundation of China(Nos.52301279 and 51901115)the Shandong Provincial Natural Science Foundation,China(ZR2023MB122 and ZR2019PEM001)+1 种基金the Outstanding Youth Innovation Team of Universities in Shandong Province(2024KJH067)the Innovation fund project for graduate student of China University of Petroleum(East China)supported by the Fundamental Research Funds for the Central Universities(No.23CX04010A)。
文摘Addressing inadequate OH^(*)adsorption in Ru Co alloy catalysts is crucial for boosting intermediate coverage and redirecting the water-splitting pathway.Herein,the adaptive P sites were strategically incorporated to overcome the aforementioned challenge.The P sites,as potent OH^(*)adsorption centers,synergize with Co sites to promote water dissociation and enrich surrounding Ru sites with H*intermediates,thus triggering the Volmer-Tafel route for hydrogen evolution reaction(HER).Besides,during the oxygen evolution reaction(OER),the surface of P-Ru Co was reconstructed into Ru-doped Co OOH with anchored PO_(4)^(3-).These PO_(4)^(3-)not only circumvent the intrinsic OH^(*)adsorption limitations of Ru-Co OOH in the adsorbate evolution mechanism(AEM)by rerouting to a more expeditious lattice oxygen oxidation mechanism(LOM)but also improve the coverage of key oxygen-containing intermediates,significantly accelerating OER kinetics.Consequently,the P-Ru Co demonstrates exceptional bifunctional performance,with overpotentials of 29 m V for HER and 222 m V for OER at 10 m A cm^(-2).Remarkably,the mass activities of PRu Co for HER(5.48 A mg^(-1))and OER(2.13 A mg^(-1))are 6.2 and 11.2 times higher than those of its commercial counterparts(Ru/C for HER and RuO_(2)for OER),respectively.When integrated into an anionexchange-membrane electrolyzer,this catalyst achieves ampere-level current densities of 1.32 A cm^(-2)for water electrolysis and 1.23 A cm^(-2)for seawater electrolysis at 2.1 V,with a 500-h durability.
基金financially supported by the National Natural Science Foundation of China(No.51804216)。
文摘Constructing heterointerface engineering has becoming an effective and general strategy for developing highly efficient and durable nonnoble electrocatalysts for catalyzing both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this work,we synthesized a self-supporting heterogeneous NiSe@Co_(0.85)Se/NF electrocatalyst using a facile in situ selenization of transition metal precursors that coated on the nickel foam(NF)in polyol solution.The NF was used as both conductive substrate and nickel source,ensuring superior electronic conductivity for catalyzing.The NiSe@-Co_(0.85)Se/NF exhibited remarkable bifunctional electrocatalytic activities with HER overpotential of 168 mV and OER overpotential of 258 mV to achieve 10 mA·cm-2.The water splitting system using NiSe@Co_(0.85)Se/NF as both anode and cathode electrodes achieved a current density of 10 mA·cm^(-2) at 1.61 V with nearly 100% faradaic efficiency and impressively long-term stability.The efficient bifunctional catalytic performance of NiSe@-Co_(0.85)Se/NF should be attributed to the electronic modulation and synergistic effect between NiSe and Co_(0.85)Se,the intrinsic metallic conductivity and the enlarged active sites exposure.This work provides a facile method for developing heterogeneous bifunctional catalysts for advanced electrochemical energy conversion technologies.
基金This study was financially supported by the National Natural Science Foundation of China(51973079,51773075 and 21875084)the Project of Department of Scienceand Technology of Jilin Province,China(20190101013JH).
文摘Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficiency of their half reactions including hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),electrocatalysts are usually essential to reduce their kinetic energy barriers.Electrospun nanomaterials possess a unique one‐dimensional structure for outstanding electron and mass transportation,large specific surface area,and the possibilities of flexibility with the porous feature,which are good candidates as efficient electrocatalysts for water splitting.In this review,we focus on the recent research progress on the electrospun nanomaterials‐based electrocatalysts for HER,OER,and overall water splitting reaction.Specifically,the insights of the influence of the electronic modulation and interface engineering of these electrocatalysts on their electrocatalytic activities will be deeply discussed and highlighted.Furthermore,the challenges and development opportunities of the electrospun nanomaterials‐based electrocatalysts for water splitting are featured.Based on the achievements of the significantly enhanced performance from the electronic modulation and interface engineering of these electrocatalysts,full utilization of these materials for practical energy conversion is anticipated.
基金supported by the Natural Science Foundation of Hebei Province(No.B2021208030)the College Students Innovation Training Program(Nos.202206224 and S2021113409001).
文摘Designing and synthesizing cost-effective bifunctional catalysts for overall alkaline water/seawater splitting is still a huge challenge for hydrogen production.Herein,Co/Ni/Fe/Mn based-amorphous high-entropy phosphoxide self-standing electrode(CNFMPO)is synthesized by the facile and fast electrodeposition method.CNFMPO exhibits excellent bifunctional electrocatalytic performances on alkaline water/seawater electrolysis.The hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)overpotentials of CNFMPO in alkaline water/seawater are as low as 43/73 and 252/282 mV to reach a current density of 10 mA cm^(-2),respectively.Additionally,two-electrode electrolyzers with CNFMPO||CNFMPO successfully achieve the current density of 10 mA cm^(-2) at low voltages of 1.54 and 1.56 V for overall alkaline water/seawater splitting,respectively.CNFMPO exhibits satisfactory long-term stability on overall alkaline water/seawater splitting for the surface reconstruction into active metal hydroxide/(oxy)hydroxide,phosphite,and phosphate.Moreover,no hypochlorite is detected during seawater electrolysis for the beneficial chlorite oxidation inhibition of the reconstructed phosphite and phosphate.The excellent catalytic performances of CNFMPO are due to the unique amorphous structure,multi-component synergistic effect,beneficial electronic structure modulation,and surface reconstruction during the catalytic reaction process.Therefore,CNFMPO has shown potential promotion to the development of the water/seawater splitting industry as a promising substituent for noble-metal electrocatalysts.This work provides new insights into the design of efficient bifunctional catalysts for overall water/seawater splitting.
文摘针对多雷达辐射源脉冲交错背景下,线性调频(Linear Frequency Modulation,LFM)信号低信噪比导致的脉冲分裂带来原始信号参数难以估计的问题,本文提出了基于深度神经网络和直方图统计的LFM信号两阶段提取与参数估计方法。首先利用双向长短时记忆网络挖掘原始脉冲流中LFM信号与非LFM信号的调制模式差异并进行分类;其次通过序列调频斜率直方图寻找LFM信号分裂脉冲序列间隐含的原始信号调频斜率信息,提取不同调频斜率的LFM信号脉冲子序列;最后在每个子序列中分别估计原始信号的参数。仿真实验结果表明,相较于传统的序列差值直方图算法和循环神经网络分选方法,本文所提方法能够更准确地提取出LFM脉冲信号,并得到较为精确的参数估计结果。
基金Project supported by the State Key Program of National Natural Science of China (Grant No 60438010)
文摘This paper demonstrates the intensity modulation characters of orthogonally polarized HeNe lasers with different optical feedback level generated by the variable reflectivity of external reflector. The modulation depths of the orthogonally polarized frequencies are increased when the optical feedback level becomes strong. It also observes that the modulation amplitudes are different for different external cavity length. Based on the vectorial extension of Lamb＇s semi-classical theory, it finds that the calculations are consistent with the experimental results.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11104156)the Postdoctoral Science Foundation of China (CPSF) (Grant No. 2012M510405)+1 种基金the Independent Research and Development Fund of Tsinghua University (Grant No. 20121087948)Beijing Key Laboratory of Fine Ceramics Opening Fund (Grant No. 2012200110)
文摘We compare the transport properties of electrons in monolayer graphene by modulating the Fermi velocity inside the barrier. A critical transmission angle is found only when the Fermi velocity in the barriers is larger than the one outside the barriers. It is shown that the transmission exhibits periodicity with the incident angle below the critical transmission angle, and attenuates exponentially in the opposite situation. For both situations, peak splitting occurs in the transmission as the number of the velocity barriers increases, and the characteristics of the transmission suggest an interesting application of an excellent band-pass filter. The dependence of the conductance on the Fermi energy through an identical velocity- modulation structure differs wildly with different Fermi velocities of the barrier. The counterpart of the peak splitting is the sharp oscillations in the conductance profile. Furthermore, some oscillations for the multiple barriers are so sharp that the structure may be used as an excellent sensor.
基金National Natural Science Foundation of China,Grant/Award Numbers:21871065,22071038Heilongjiang Touyan Team,Grant/Award Number:HITTY‐20190033Interdisciplinary Research Foundation of HIT,Grant/Award Number:IR2021205。
文摘Herein,we report bifunctional molybdenum-doped nickel sulfide on nickel foam(Mo-NiS_(x)/NF)for magnetic field-enhanced overall water splitting under alkaline conditions.Proper doping of Mo can lead to optimization of the electronic structure of NiS_(x),which accelerates the dissociation of H2O and the adsorption of OH−in the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)processes,respectively.In addition,the magnetically active Mo-NiS_(x)/NF can further enhance the HER and OER activity under an applied magnetic field due to the magnetoresistance effect and the ferromagnetic(FM)exchange-field penetration effect.As a result,Mo-NiS_(x)/NF requires low overpotentials of 307 mV at 50mA cm^(−2)(for OER)and 136 mV at 10mA cm^(−2)(for HER)under a magnetic field of 10000 G.Furthermore,the electrolytic cell constructed by the bifunctional Mo-NiS_(x)/NFs as both the cathode and the anode shows a low cell voltage of 1.594 V at 10 mA cm^(−2)with optimal stability over 60 h under the magnetic field.Simultaneous enhancement of the HER and OER processes by an external magnetic field through rational design of electrocatalysts might be promising for overall water splitting applications.
基金Project supported by the National Natural Science Foundation of China(Grant No.10774044)the National Key Basic Research and Development Program of China(Grant No.2010CB922903)+1 种基金the Science Foundation of the Science and Technology Commission of Shanghai Municipality of China(Grant No.07JC14019)the Shanghai Pujiang Talent Program of China(Grant No.07PJ14038)
文摘We report the experimental results on measuring the isotope shifts and hyperfine splittings of all ytterbium isotopes for a 399-nm transition by using a quite simple and novel method. It benefits from the advantages of the modulation transfer spectroscopy in an ytterbium hollow cathode lamp and the Doppler-free spectroscopy in a collimated ytterbium atomic beam. The key technique in this experiment is simultaneously measuring the frequency separations of the two spectra twice, and the separation difference between two measurements is solely determined by the well-defined frequency of an acousto-optics modulator. Compared with the most of previously reported experimental results, ours are more accurate and completed, which will provide the useful information for developing a more accurate theoretical model to describe the interaction inside an ytterbium atom.
文摘After defining Hom(chi (A), eta (B)) and chi (A) circle times eta (B) in the fuzzy modular category Fm, the sufficient conditions of the existence for exact Hom functors Hom(delta (M),), and Hom(, delta (M)), as well as exact Tensor functors delta (M)circle times and circle times delta (M) are given in this paper. Finally the weak isomorphisms relations between Horn functors and Tensor functors are displayed.
文摘Let F be a locally defined formation consisting of locally solvable groups, G a hyper-（ cyclic or finite） locally solvable group and A a noetherian ZG-module with all irreducible ZG-factors being finite. The following conclusion is obtained： if G∈F, f（ ∞ ） include f（p）, f（p） ≠φ for each p∈π, and A has no nonzero F central ZG- images, then any extension E of A by G splits conjugately over A, and A has no nonzero F central ZG-factors.
