The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temper...The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temperature in aero-derivative gas turbines,a lot of effort has been made to prevent the premature failure of columnar 7YSZ TBCs,which is induced by the microstructure degradation,sintering and spallation after the deposition of infiltrated siliceous mineral(consisting of calcium magnesium aluminum silicate(CaO MgO Al2O3 SiO2,i.e.,CMAS)).A new method called Al-modification for columnar 7YSZ TBCs against CMAS corrosion was present.The Al film was magnetron-sputtered on the surface of the columnar 7YSZ TBCs,followed by performing vacuum heat treatment of the Al-deposited TBCs.During the heat treatment,the molten Al reacted with ZrO2 to formα-Al2O3 overlay that effectively hindered CMAS infiltration.Moreover,the Al film could evaporate and re-nucleate,leading to the generation of Al2O3 nanowires,which further restrained the moving of molten CMAS.展开更多
Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes compar...Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical(PEC) performances. Here, we demonstrate for the first time that super-long Cu_2O NWs, more than 4.5 μm,with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide(AAO) template method. In comparison with the photocathode with planar Cu_2O films, the photocathode with Cu_2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm^2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectrochemical electrode through depositing Pt NPs with atomic layer deposition(ALD) technology on the Cu_2O NWs, the plateau of photocurrent has been enlarged to –7 mA/cm^2 with the external quantum yield up to 34% at 410 nm. This study suggests that the photoelectrode based on Cu_2O NWs is a hopeful system for establishing high-efficiency water splitting system under visible light.展开更多
Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays stru...Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth(CC)by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^(-2) and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor(ASC)using NiCo_2O_4@CC as positive electrode and activated carbon cloth(ACC) as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^(-2)(12.5 F cm^(-3)), a high energy density of 0.24 mWh cm^(-2)(3.91 mWh cm^(-3)), as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.展开更多
In this work, we prepared the β-Ga_2O_3@GaN nanowires(NWs) by oxidizing GaN NWs. High-quality hexagonal wurtzite GaN NWs were achieved and the conversion from GaN to β-Ga_2O_3 was confirmed by x-ray diffraction, Ram...In this work, we prepared the β-Ga_2O_3@GaN nanowires(NWs) by oxidizing GaN NWs. High-quality hexagonal wurtzite GaN NWs were achieved and the conversion from GaN to β-Ga_2O_3 was confirmed by x-ray diffraction, Raman spectroscopy and transmission electron microscopy. The effect of the oxidation temperature and time on the oxidation degree of GaN NWs was investigated systematically. The oxidation rate of GaN NWs was estimated at different temperatures.展开更多
Mn2O3 nanowires with diameters of about 130 nm and lengths up to tens of micrometers were synthesized by the thermal decomposition of MnCO3 precursors. It was identified that the growth of the cubic Mn2O nanowires was...Mn2O3 nanowires with diameters of about 130 nm and lengths up to tens of micrometers were synthesized by the thermal decomposition of MnCO3 precursors. It was identified that the growth of the cubic Mn2O nanowires was preferential along the [001] direction. The intermediate stage containing melting state and the particles of manganese oxide played an important role for the formation of Mn2O3 with one-dimensional structure. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the morphology and crystal structure of the precursors and final products. Thermogravimetry analysis was also carried out to find the mechanism for the formation of Mn2O3 nanowires. The growth of the nanowires was proposed to be dominated by the conventional melt-growth mechanism.展开更多
The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic propert...The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic properties and adsorption properties of these obtained ferrites with different morphologies were studied contrastively.Results show that the obtained samples exhibit ferromagnetic properties.This realizes convenient magnetic separation from solution when they are used in the treatment of organic dyes wastewater.However,the contrastive studies show that the saturation magnetizations(Ms) of MnFe2O4 with different morphologies are different and the Ms follows the order:Ms(porous)〈Ms(nanoparticles)〈Ms(nanowires).In addition,the adsorptions of methylene blue(MB) onto these ferrites depend on ferrites' morphologies seriously.The adsorption rate of MB on the porous MnFe2O4 is much higher than those onto the other two samples because the porous structure can provide high efficient mass transport through the pores.展开更多
In this paper, the Ag2O nanowires had been prepared and applied for the fabrication of ascorbic acid sensors with high enhanced sensitivity by using self-assembly technology. The structures and morphologies of Ag2O na...In this paper, the Ag2O nanowires had been prepared and applied for the fabrication of ascorbic acid sensors with high enhanced sensitivity by using self-assembly technology. The structures and morphologies of Ag2O nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The direct electrocatalytic oxidation of ascorbic acid in alkaline medium at Ag2O nanowires modified electrodes had been investigated in detail and the condition for determination of ascorbic acid was optimized, such as support-electrolyte, pH and scan speed. The oxidation peak current changed linearly with the concentration of ascorbic acid over the range from 2.0×10-8 mol/L to 1.0 mmol/L, and the detection limit can reach 1.0×10-8mol/L. Compared to a bare Ag electrode, a substantial decrease in the overvoltage of the ascorbic acid oxidation was observed at the Ag nanowires electrodes with oxidation starting at ca. 0.7V vs. Ag/AgCl (saturated KCl). The Ag2O nanowires modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of ascorbic acid, thus is promising for the future development of non-enzymatic ascorbic acid sensors.展开更多
The thermal stability of α-Fe203 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scannin...The thermal stability of α-Fe203 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scanning electron microscopy. The α-Fe2O3 nanowires are stable at the temperatures up to 600℃, and the crystalline structure becomes more perfect after annealing. This behavior supplies a way to improve the quality of the α-Fe2O3 nanowires. The γ-Fe2O3 nanowires become unstable when annealed at 350℃. Raman spectra of both nanowires have been measured, which also indicate that the γ-Fe203 nanowires are transformed into α-Fe2O3 under the strong laser beam.展开更多
Fe-doped In2O3 dilute magnetic semiconducting nanowires are fabricated on A u-deposited Si substrates by the chemical vapor deposition technique. It is confirmed by energy dispersive x-ray spectroscopy (EDS), x-ray ...Fe-doped In2O3 dilute magnetic semiconducting nanowires are fabricated on A u-deposited Si substrates by the chemical vapor deposition technique. It is confirmed by energy dispersive x-ray spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy that Fe has been successfully doped into lattices of In2O3 nanowires. The EDS measurements reveal a large amount of oxygen vacancies existing in the Fe-doped In2O3 nanowires. The Fe dopant exists as a mixture of Fe2+ and Fe3+, as revealed by the XPS. The origin of room-temperature ferromagnetism in Fe-doped In2O3 nanowires is explained by the bound magnetic polaron model.展开更多
Ga2O3 nano-structures, nanowires and nanosheets are produced on Au pre-coated(111) silicon substrates with chemical vapor deposition(CVD) technique. By evaporating pure Ga powder in the H2O atmosphere under ambient pr...Ga2O3 nano-structures, nanowires and nanosheets are produced on Au pre-coated(111) silicon substrates with chemical vapor deposition(CVD) technique. By evaporating pure Ga powder in the H2O atmosphere under ambient pressure the large-scale preparation of β-Ga2O3 with monoclinic crystalline structure is achieved. The crystalline structures and morphologies of produced Ga2O3 nano-structures are characterized by means of scanning electron microscope(SEM), X-ray diffraction(XRD), selected area electron diffraction(SAED) and transmission electron microscope(TEM). Raman spectrum reveals the typical vibration modes of Ga2O3. The vibration mode shifts corresponding to Ga2O3 nano-structures are not found. Two distinguish photoluminescence(PL) emissions are found at about 399 nm and 469 nm owing to the VO-VGa excitation and VO-VGa-O excitation, respectively. The growth mechanisms of Ga2O3 nanowires and nanosheets are discussed with vapor-liquid-solid(VLS) and vapor-solid(VS) mechanisms.展开更多
β-Mn2V2O7 crystals with strip shape are successfully prepared by the molten salt method in a closed crucible, and are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission ele...β-Mn2V2O7 crystals with strip shape are successfully prepared by the molten salt method in a closed crucible, and are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area of electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The results indicate that the sample is of the β-Mn2V2O7 crystal with monoclinic symmetry, level natural cleavage facets and directional growth. Magnetic properties are measured by vibration sample magnetometry (VSM) at room temperature, and the magnetic hysteresis loop indicates that the β-Mn2V2O7 has anti-ferromagnetic properties with low coercive force and remnant magnetization. The magnetic measurement results in different directions exhibit that the β-Mn2V2O7 has magnetic anisotropy, which is due to the fact that the magnetic interaction energy of the β-Mn2V2O7 is lowest only when the electron configuration is in a certain direction.展开更多
Aqueous Zinc-ion batteries(ZIB) are attracting immense attention because of their merits of excellent safety and quite cheap properties compared with lithium-ion batteries(LIB).Manganese oxide is one of the most impor...Aqueous Zinc-ion batteries(ZIB) are attracting immense attention because of their merits of excellent safety and quite cheap properties compared with lithium-ion batteries(LIB).Manganese oxide is one of the most important cathode materials of ZIB.In this paper,α-Mn2O3 used as cathode of ZIB is synthesized via Metal-Organic Framework(MOF)-derived method,which delivers a high specific capacity of225 mAh g^(-1) at 0.05 A g^(-1) and 92.7 mAh g^(-1) after 1700 cycles at 2 A g^(-1).The charge storage mechanism of α-Mn2O3 cathode is found to greatly depend on the discharge current density.At lower current density discharging,the H+ and Zn2+ are successively intercalated into the α-Mn2O3 before and after the "turning point" of discharge voltage and their discharging products present obviously different morphologies changing from flower-like to large plate-like products.At a higher current density,the low-voltage plateau after the turning point disappears due to the decrease of amount of Zn2+ intercalation and the H+intercalation is dominated in α-Mn2 O3.This study provides significant understanding for future design and research of high-performance Mn-based cathodes of ZIB.展开更多
基金Project(2017YFB0306100) supported by the National Key Research&Development Plan of ChinaProjects(51801034,51771059) supported by the National Natural Science Foundation of China+3 种基金Projects(2018GDASCX-0949,2018GDASCX-0950,2017GDASCX-0111) supported by the Guangdong Academy of Sciences,ChinaProjects(2017B090916002,2017A070701027) supported by the Guangdong Technical Research Program,ChinaProjects(2016A030312015,2017A030310315) supported by the Natural Science Foundation of Guangdong Province,ChinaProjects(201605131008557,201707010385) supported by the Technical Research Program of Guangzhou City,China
文摘The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temperature in aero-derivative gas turbines,a lot of effort has been made to prevent the premature failure of columnar 7YSZ TBCs,which is induced by the microstructure degradation,sintering and spallation after the deposition of infiltrated siliceous mineral(consisting of calcium magnesium aluminum silicate(CaO MgO Al2O3 SiO2,i.e.,CMAS)).A new method called Al-modification for columnar 7YSZ TBCs against CMAS corrosion was present.The Al film was magnetron-sputtered on the surface of the columnar 7YSZ TBCs,followed by performing vacuum heat treatment of the Al-deposited TBCs.During the heat treatment,the molten Al reacted with ZrO2 to formα-Al2O3 overlay that effectively hindered CMAS infiltration.Moreover,the Al film could evaporate and re-nucleate,leading to the generation of Al2O3 nanowires,which further restrained the moving of molten CMAS.
基金supported by European Research Council(HiNaPc:737616)European Research Council(ThreeDsurface:240144)+8 种基金BMBF(ZIK-3DNanoDevice:03Z1MN11)DFG(LE2249_4-1)BMBF(Meta-ZIK-BioLithoMorphie:03Z1M511)National Natural Science Foundation of China(Nos.21577086,51702130,21503209)Natural Science Foundation of Jiangsu Province(BK 20170550)Jiangsu Specially-Appointed Professor ProgramHundred-Talent Program(Chinese Academy of Sciences)Beijing Natural Science Foundation(No.2162042)Key Research Program of Frontier Science,CAS(No.QYZDBSSW-SLH006)
文摘Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical(PEC) performances. Here, we demonstrate for the first time that super-long Cu_2O NWs, more than 4.5 μm,with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide(AAO) template method. In comparison with the photocathode with planar Cu_2O films, the photocathode with Cu_2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm^2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectrochemical electrode through depositing Pt NPs with atomic layer deposition(ALD) technology on the Cu_2O NWs, the plateau of photocurrent has been enlarged to –7 mA/cm^2 with the external quantum yield up to 34% at 410 nm. This study suggests that the photoelectrode based on Cu_2O NWs is a hopeful system for establishing high-efficiency water splitting system under visible light.
基金supported by the National Natural Science Foundation of China(Grant nos.51402324,51402325,51302281)
文摘Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth(CC)by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^(-2) and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor(ASC)using NiCo_2O_4@CC as positive electrode and activated carbon cloth(ACC) as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^(-2)(12.5 F cm^(-3)), a high energy density of 0.24 mWh cm^(-2)(3.91 mWh cm^(-3)), as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.
基金Project supported by National Key Research and Development Program of China(Grant No.2017YFB0404201)State Key Research and Development Program of Jiangsu Province,China(Grant No.BE2018115)+1 种基金the Fund from the Solid-state Lighting&Energy-saving Electronics Collaborative Innovation Center,PAPDthe Fund from the State Grid Shandong Electric Power Company
文摘In this work, we prepared the β-Ga_2O_3@GaN nanowires(NWs) by oxidizing GaN NWs. High-quality hexagonal wurtzite GaN NWs were achieved and the conversion from GaN to β-Ga_2O_3 was confirmed by x-ray diffraction, Raman spectroscopy and transmission electron microscopy. The effect of the oxidation temperature and time on the oxidation degree of GaN NWs was investigated systematically. The oxidation rate of GaN NWs was estimated at different temperatures.
基金Supported by the Program for New Century Excellent Talents in University of China(No.NCET-04-0653)
文摘Mn2O3 nanowires with diameters of about 130 nm and lengths up to tens of micrometers were synthesized by the thermal decomposition of MnCO3 precursors. It was identified that the growth of the cubic Mn2O nanowires was preferential along the [001] direction. The intermediate stage containing melting state and the particles of manganese oxide played an important role for the formation of Mn2O3 with one-dimensional structure. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the morphology and crystal structure of the precursors and final products. Thermogravimetry analysis was also carried out to find the mechanism for the formation of Mn2O3 nanowires. The growth of the nanowires was proposed to be dominated by the conventional melt-growth mechanism.
基金Supported by the Fundamental Research Funds for the Central Universities of China(No.HEUCF101015)the Open Research Fund Program of State Key Laboratory of Rare Earth Resuorce Utilization,China(No.RERU2011004)
文摘The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic properties and adsorption properties of these obtained ferrites with different morphologies were studied contrastively.Results show that the obtained samples exhibit ferromagnetic properties.This realizes convenient magnetic separation from solution when they are used in the treatment of organic dyes wastewater.However,the contrastive studies show that the saturation magnetizations(Ms) of MnFe2O4 with different morphologies are different and the Ms follows the order:Ms(porous)〈Ms(nanoparticles)〈Ms(nanowires).In addition,the adsorptions of methylene blue(MB) onto these ferrites depend on ferrites' morphologies seriously.The adsorption rate of MB on the porous MnFe2O4 is much higher than those onto the other two samples because the porous structure can provide high efficient mass transport through the pores.
基金Sponsored by the Foundation of Chongqing Education Commission of China (Grant No. KJ051201)
文摘In this paper, the Ag2O nanowires had been prepared and applied for the fabrication of ascorbic acid sensors with high enhanced sensitivity by using self-assembly technology. The structures and morphologies of Ag2O nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The direct electrocatalytic oxidation of ascorbic acid in alkaline medium at Ag2O nanowires modified electrodes had been investigated in detail and the condition for determination of ascorbic acid was optimized, such as support-electrolyte, pH and scan speed. The oxidation peak current changed linearly with the concentration of ascorbic acid over the range from 2.0×10-8 mol/L to 1.0 mmol/L, and the detection limit can reach 1.0×10-8mol/L. Compared to a bare Ag electrode, a substantial decrease in the overvoltage of the ascorbic acid oxidation was observed at the Ag nanowires electrodes with oxidation starting at ca. 0.7V vs. Ag/AgCl (saturated KCl). The Ag2O nanowires modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of ascorbic acid, thus is promising for the future development of non-enzymatic ascorbic acid sensors.
基金the National Natural Science Foundation of China under grant Nos.10374003 and 10434010.
文摘The thermal stability of α-Fe203 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scanning electron microscopy. The α-Fe2O3 nanowires are stable at the temperatures up to 600℃, and the crystalline structure becomes more perfect after annealing. This behavior supplies a way to improve the quality of the α-Fe2O3 nanowires. The γ-Fe2O3 nanowires become unstable when annealed at 350℃. Raman spectra of both nanowires have been measured, which also indicate that the γ-Fe203 nanowires are transformed into α-Fe2O3 under the strong laser beam.
基金Supported by the National Basic Research Program of China under Grant Nos 2014CB921101,2014CB921103 and2013CB922103the National Natural Science Foundation of China under Grant Nos 11274003,61176088 and 61274102+1 种基金the Program for the New Century Excellent Talents in University under Grant No NCET-11-0240the PAPD Project,and the Fundamental Research Funds for the Central Universities
文摘Fe-doped In2O3 dilute magnetic semiconducting nanowires are fabricated on A u-deposited Si substrates by the chemical vapor deposition technique. It is confirmed by energy dispersive x-ray spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy that Fe has been successfully doped into lattices of In2O3 nanowires. The EDS measurements reveal a large amount of oxygen vacancies existing in the Fe-doped In2O3 nanowires. The Fe dopant exists as a mixture of Fe2+ and Fe3+, as revealed by the XPS. The origin of room-temperature ferromagnetism in Fe-doped In2O3 nanowires is explained by the bound magnetic polaron model.
文摘Ga2O3 nano-structures, nanowires and nanosheets are produced on Au pre-coated(111) silicon substrates with chemical vapor deposition(CVD) technique. By evaporating pure Ga powder in the H2O atmosphere under ambient pressure the large-scale preparation of β-Ga2O3 with monoclinic crystalline structure is achieved. The crystalline structures and morphologies of produced Ga2O3 nano-structures are characterized by means of scanning electron microscope(SEM), X-ray diffraction(XRD), selected area electron diffraction(SAED) and transmission electron microscope(TEM). Raman spectrum reveals the typical vibration modes of Ga2O3. The vibration mode shifts corresponding to Ga2O3 nano-structures are not found. Two distinguish photoluminescence(PL) emissions are found at about 399 nm and 469 nm owing to the VO-VGa excitation and VO-VGa-O excitation, respectively. The growth mechanisms of Ga2O3 nanowires and nanosheets are discussed with vapor-liquid-solid(VLS) and vapor-solid(VS) mechanisms.
文摘β-Mn2V2O7 crystals with strip shape are successfully prepared by the molten salt method in a closed crucible, and are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area of electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The results indicate that the sample is of the β-Mn2V2O7 crystal with monoclinic symmetry, level natural cleavage facets and directional growth. Magnetic properties are measured by vibration sample magnetometry (VSM) at room temperature, and the magnetic hysteresis loop indicates that the β-Mn2V2O7 has anti-ferromagnetic properties with low coercive force and remnant magnetization. The magnetic measurement results in different directions exhibit that the β-Mn2V2O7 has magnetic anisotropy, which is due to the fact that the magnetic interaction energy of the β-Mn2V2O7 is lowest only when the electron configuration is in a certain direction.
基金supported by the National Natural Science Foundation of China (51672156)Local Innovative Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01N111)+2 种基金Guangdong Province Technical Plan Project (2017B010119001)Shenzhen Technical Plan Project (JCYJ20170817161221958 and JCYJ20170412170706047)Shenzhen Graphene Manufacturing Innovation Center (201901161513)。
文摘Aqueous Zinc-ion batteries(ZIB) are attracting immense attention because of their merits of excellent safety and quite cheap properties compared with lithium-ion batteries(LIB).Manganese oxide is one of the most important cathode materials of ZIB.In this paper,α-Mn2O3 used as cathode of ZIB is synthesized via Metal-Organic Framework(MOF)-derived method,which delivers a high specific capacity of225 mAh g^(-1) at 0.05 A g^(-1) and 92.7 mAh g^(-1) after 1700 cycles at 2 A g^(-1).The charge storage mechanism of α-Mn2O3 cathode is found to greatly depend on the discharge current density.At lower current density discharging,the H+ and Zn2+ are successively intercalated into the α-Mn2O3 before and after the "turning point" of discharge voltage and their discharging products present obviously different morphologies changing from flower-like to large plate-like products.At a higher current density,the low-voltage plateau after the turning point disappears due to the decrease of amount of Zn2+ intercalation and the H+intercalation is dominated in α-Mn2 O3.This study provides significant understanding for future design and research of high-performance Mn-based cathodes of ZIB.