Micro-nano structured Li Fe（1-x）MnxPO4/C（0≤x≤0.05）cathodes were prepared by spray drying,followed by calcination at 700°C.The spherical Li Fe（1-x）MnxPO4/C（0≤x≤0.05）particles with the size of 0.5 to5.0...Micro-nano structured Li Fe（1-x）MnxPO4/C（0≤x≤0.05）cathodes were prepared by spray drying,followed by calcination at 700°C.The spherical Li Fe（1-x）MnxPO4/C（0≤x≤0.05）particles with the size of 0.5 to5.0μm are composed of lots of nanoparticles of 20 to 30 nm,and have the well-developed interconnected pore structure.In contrast,when Mn doping content is 3 mol%（x=0.03）,the Li Fe（0.97）Mn（0.03）PO4/C demonstrates maximum specific surface area of 31.30 m^2/g,more uniform pore size and relatively better electrochemical performance.The initial discharge capacities are 161.59,157.04 and 153.13 m Ah/g at a discharge rate of 0.2,0.5 and 1 C,respectively.Meanwhile,the discharge capacity retentions are～100%after 120 cycles.The improved electrochemical performance should be attributed to higher specific surface,smaller polarization voltage,and a high Li~＋diffusion rate due to the micro-nano porous structure and lattice expansion produced by Mn doping.展开更多
The temperature dependences of upper critical field(Hc2) for a series of iron-deficient Fe1-xSe single crystals are obtained from the measurements of in-plane resistivity in magnetic fields up to 9 T and perpendicular...The temperature dependences of upper critical field(Hc2) for a series of iron-deficient Fe1-xSe single crystals are obtained from the measurements of in-plane resistivity in magnetic fields up to 9 T and perpendicular to the ab plane. For the samples with lower superconducting transition temperature Tc(< 7.2 K), the temperature dependence of Hc2 is appropriately described by an effective two-band model. For the samples with higher Tc( 7.2 K), the temperature dependence can also be fitted by a single-band Werthamer–Helfand–Hohenberg formula, besides the two-band model. Such a Tc-dependent change in Hc2(T) behavior is discussed in connection with recent related experimental results, showing an inherent link between the changes of intrinsic superconducting and normal state properties in the Fe Se system.展开更多
Structure, magnetic properties and magnetostriction of Sm0.9Pr0.1(Fe1-xCox)2 compounds have been investigated by means of X-ray diffraction, a.c. initial susceptibility, extracting sample magnetometer, Mossbauer spec-...Structure, magnetic properties and magnetostriction of Sm0.9Pr0.1(Fe1-xCox)2 compounds have been investigated by means of X-ray diffraction, a.c. initial susceptibility, extracting sample magnetometer, Mossbauer spec-troscopy and standard strain gauge techniques. The lattice parameter a of the MgCu2-type Laves compounds Sm0.9Pr0.1(Fe1-xCox)2 decreases nonlinearly with increasing Co concentration, deviating from the Vegard's law. Curie temperature Tc increases initially from 668 K for x=0 to 694 K for x=0.2 and then decreases to 200 K for x=1.0. The saturation magnetization Ms at temperatures 1.5 K, 77 K and 300 K have the same variation tendency as the composition dependence of Curie temperature, in consistence with rigid-band model. The easy magnetization direction (EMD) of Sm0.9Pr0.1(Fe1-xCox)2 lies along [111] direction in the range x<0.6, and changes to [110] for x=0.8, while Sm0.9Pr0.1Co2 stays in the paramagnetic state at room temperature. The composition dependence of the average hyperfine field,Hhf , demonstrates a similar variation tendency as that of the saturation magnetization Ms and Curie temperature Tc. The spontaneous magnetostricton Am increases with increasing Co content. The saturation magnetostriction λs decreases monotonically with increasing x, which is caused by the increase of magnetostriction constant λ100 with opposite sign to that of Am. A two-sublattice model has been proposed to understand the intermediate region between the [111] and [110] spin configurations, which can also be used to explain the temperature dependence of magnetization.展开更多
Constructing potential anodes for sodium-ion batteries(SIBs)with a wide temperature property has captured enormous interests in recent years.Fe1-xS,a zero-band gap material confirmed by density states calculation,is a...Constructing potential anodes for sodium-ion batteries(SIBs)with a wide temperature property has captured enormous interests in recent years.Fe1-xS,a zero-band gap material confirmed by density states calculation,is an ideal electrode for fast energy storage on account of its low cost and high theoretical capacity.Herein,Fe1-xS nanosheet wrapped by nitrogen-doped carbon(Fe1-xS@NC)is engineered through a post-sulfidation strategy using Fe-based metal-organic framework(Fe-MOF)as the precursor.The obtained Fe1-xS@NC agaric-like structure can well shorten the charge diffusion pathway,and significantly enhance the ionic/electronic conductivities and the reaction kinetics.As expected,the Fe1-xS@NC electrode,as a prospective SIB anode,delivers a desirable capacity up to 510.2 mA h g^-1 at a high rate of8000 mA g^-1.Additionally,even operated at low temperatures of 0 and-25°C,high reversible capacities of 387.1 and 223.4 mA h g^-1 can still be obtained at 2000 mA g^-1,respectively,indicating its huge potential use at harsh temperatures.More noticeably,the full battery made by the Fe1-xS@NC anode and Na3 V2(PO4)2 O2 F cathode achieves a remarkable rate capacity(186.8 mA h g^-1 at 2000 m A g^-1)and an impressive cycle performance(183.6 m A h g^-1 after 100 cycles at700 mA g^-1)between 0.3 and 3.8 V.Such excellent electrochemical performance is mainly contributed by its pseudocapacitive-dominated behavior,which brings fast electrode kinetics and robust structural stability to the whole electrode.展开更多
Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting.However,their widespread use as bifunctional electrocatalysts is hindered by low metal loading,inefficient yield,and c...Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting.However,their widespread use as bifunctional electrocatalysts is hindered by low metal loading,inefficient yield,and complex synthesis processes.In this work,platinum atoms were anchored onto nickel-iron layered double hydroxide/carbon nanotube(LDH/CNT)hybrid electrocatalysts by using a straightforward milling technique with K_(2)Pt Cl_(6)·6H_(2)O as the Pt source.By adjusting the Pt-to-Fe ratio to 1/2 and 1/10,excellent electrocatalysts—Pt_(1/6)-Ni_(2/3)Fe_(1/3)-LDH/CNT and Pt_(1/30)-Ni_(2/3)Fe_(1/3)-LDH/CNT—were achieved with superior performance in hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),outperforming the corresponding commercial Pt/C(20 wt%)and Ru O_(2)electrocatalysts.The enhanced electrochemical performance is attributed to the modification of Pt's electronic structure,which exhibits electron-rich states for HER and electrondeficient states for OER,significantly boosting Pt's electrochemical activity.Furthermore,the simple milling technology for controlling Pt loading offers a promising approach for scaling up the production of electrocatalysts.展开更多
基金Project（60534020） supported by the National Natural Science Foundation of China Project（03G51019） supported by the Aeronautics Foundation of China+1 种基金 Project（04-0165） supported by the New Century Programme for Excellent Talents of the Ministry of Education of China Project（400152） supported by the Innovation Research Foundation for PhD student of BUAA
基金financially supported by the Department of Education of Liaoning Province of China
文摘Micro-nano structured Li Fe（1-x）MnxPO4/C（0≤x≤0.05）cathodes were prepared by spray drying,followed by calcination at 700°C.The spherical Li Fe（1-x）MnxPO4/C（0≤x≤0.05）particles with the size of 0.5 to5.0μm are composed of lots of nanoparticles of 20 to 30 nm,and have the well-developed interconnected pore structure.In contrast,when Mn doping content is 3 mol%（x=0.03）,the Li Fe（0.97）Mn（0.03）PO4/C demonstrates maximum specific surface area of 31.30 m^2/g,more uniform pore size and relatively better electrochemical performance.The initial discharge capacities are 161.59,157.04 and 153.13 m Ah/g at a discharge rate of 0.2,0.5 and 1 C,respectively.Meanwhile,the discharge capacity retentions are～100%after 120 cycles.The improved electrochemical performance should be attributed to higher specific surface,smaller polarization voltage,and a high Li~＋diffusion rate due to the micro-nano porous structure and lattice expansion produced by Mn doping.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11888101 and 11834016)the National Key Research and Development Program of China(Grant Nos.2017YFA0303003 and 2016YFA0300300)the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-SLH001 and XDB25000000)
文摘The temperature dependences of upper critical field(Hc2) for a series of iron-deficient Fe1-xSe single crystals are obtained from the measurements of in-plane resistivity in magnetic fields up to 9 T and perpendicular to the ab plane. For the samples with lower superconducting transition temperature Tc(< 7.2 K), the temperature dependence of Hc2 is appropriately described by an effective two-band model. For the samples with higher Tc( 7.2 K), the temperature dependence can also be fitted by a single-band Werthamer–Helfand–Hohenberg formula, besides the two-band model. Such a Tc-dependent change in Hc2(T) behavior is discussed in connection with recent related experimental results, showing an inherent link between the changes of intrinsic superconducting and normal state properties in the Fe Se system.
基金This work has been supported by the projects No.59725103 and 59871054 of the National Natural Sciences Foundation of China and by the Science and Technology Commnission of Shenyang and Liaoning.Z.J.Guo as aiso indebted to Prof.A.S.Miarkosyan(Russia)for helpful discussions.
文摘Structure, magnetic properties and magnetostriction of Sm0.9Pr0.1(Fe1-xCox)2 compounds have been investigated by means of X-ray diffraction, a.c. initial susceptibility, extracting sample magnetometer, Mossbauer spec-troscopy and standard strain gauge techniques. The lattice parameter a of the MgCu2-type Laves compounds Sm0.9Pr0.1(Fe1-xCox)2 decreases nonlinearly with increasing Co concentration, deviating from the Vegard's law. Curie temperature Tc increases initially from 668 K for x=0 to 694 K for x=0.2 and then decreases to 200 K for x=1.0. The saturation magnetization Ms at temperatures 1.5 K, 77 K and 300 K have the same variation tendency as the composition dependence of Curie temperature, in consistence with rigid-band model. The easy magnetization direction (EMD) of Sm0.9Pr0.1(Fe1-xCox)2 lies along [111] direction in the range x<0.6, and changes to [110] for x=0.8, while Sm0.9Pr0.1Co2 stays in the paramagnetic state at room temperature. The composition dependence of the average hyperfine field,Hhf , demonstrates a similar variation tendency as that of the saturation magnetization Ms and Curie temperature Tc. The spontaneous magnetostricton Am increases with increasing Co content. The saturation magnetostriction λs decreases monotonically with increasing x, which is caused by the increase of magnetostriction constant λ100 with opposite sign to that of Am. A two-sublattice model has been proposed to understand the intermediate region between the [111] and [110] spin configurations, which can also be used to explain the temperature dependence of magnetization.
基金financially supported by the National Natural Science Foundation of China (21873018, 21573036 and 21274017)the open project of Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis (130028655)
文摘Constructing potential anodes for sodium-ion batteries(SIBs)with a wide temperature property has captured enormous interests in recent years.Fe1-xS,a zero-band gap material confirmed by density states calculation,is an ideal electrode for fast energy storage on account of its low cost and high theoretical capacity.Herein,Fe1-xS nanosheet wrapped by nitrogen-doped carbon(Fe1-xS@NC)is engineered through a post-sulfidation strategy using Fe-based metal-organic framework(Fe-MOF)as the precursor.The obtained Fe1-xS@NC agaric-like structure can well shorten the charge diffusion pathway,and significantly enhance the ionic/electronic conductivities and the reaction kinetics.As expected,the Fe1-xS@NC electrode,as a prospective SIB anode,delivers a desirable capacity up to 510.2 mA h g^-1 at a high rate of8000 mA g^-1.Additionally,even operated at low temperatures of 0 and-25°C,high reversible capacities of 387.1 and 223.4 mA h g^-1 can still be obtained at 2000 mA g^-1,respectively,indicating its huge potential use at harsh temperatures.More noticeably,the full battery made by the Fe1-xS@NC anode and Na3 V2(PO4)2 O2 F cathode achieves a remarkable rate capacity(186.8 mA h g^-1 at 2000 m A g^-1)and an impressive cycle performance(183.6 m A h g^-1 after 100 cycles at700 mA g^-1)between 0.3 and 3.8 V.Such excellent electrochemical performance is mainly contributed by its pseudocapacitive-dominated behavior,which brings fast electrode kinetics and robust structural stability to the whole electrode.
基金supported by the Natural Science Foundation of Henan(242300421230)the Young Teacher Fundamental Research Cultivation Program of Zhengzhou University(JC23557030)the National Natural Science Foundation of China(U21A20281 and 22208322)。
文摘Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting.However,their widespread use as bifunctional electrocatalysts is hindered by low metal loading,inefficient yield,and complex synthesis processes.In this work,platinum atoms were anchored onto nickel-iron layered double hydroxide/carbon nanotube(LDH/CNT)hybrid electrocatalysts by using a straightforward milling technique with K_(2)Pt Cl_(6)·6H_(2)O as the Pt source.By adjusting the Pt-to-Fe ratio to 1/2 and 1/10,excellent electrocatalysts—Pt_(1/6)-Ni_(2/3)Fe_(1/3)-LDH/CNT and Pt_(1/30)-Ni_(2/3)Fe_(1/3)-LDH/CNT—were achieved with superior performance in hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),outperforming the corresponding commercial Pt/C(20 wt%)and Ru O_(2)electrocatalysts.The enhanced electrochemical performance is attributed to the modification of Pt's electronic structure,which exhibits electron-rich states for HER and electrondeficient states for OER,significantly boosting Pt's electrochemical activity.Furthermore,the simple milling technology for controlling Pt loading offers a promising approach for scaling up the production of electrocatalysts.
