Fe/N/C catalysts,synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors,have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity i...Fe/N/C catalysts,synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors,have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity in fuel cells and/or metal-air batteries.However,post-treatments (acid washing,second pyrolysis,and so on) are unavoidable to improve ORR catalytic activity and stability.The method for introducing Fe^(3+) sources (anhydrous Fe Cl_(3)) into the MOF structure,in particular,is a critical step that can avoid time-consuming post-treatments and result in more exposed Fe-N_(x) active sites.Herein,three different Fe doping strategies were systematically investigated to explore their influence on the types of active sites formed and ORR performance.Fe-NC(Zn^(2+)),synthesized by one-step pyrolysis of Fe doped ZIF-8 (Zn^(2+)) precursor which was obtained by adding the anhydrous Fe Cl_(3)source into the Zn(NO_(3))_(2)·6H_(2)O/methanol solution before mixing,possessed the highest Fe-N_(x)active sites due to the high-efficiency substitution of Zn^(2+)ions with Fe^(3+) ions during ZIF-8 growth,the strong interaction between Fe^(3+) ions and N atoms of 2-Methylimidazole (2-MIm),and ZIF-8’s micropore confinement effect.As a result,Fe-NC(Zn^(2+)) presented high ORR activity in the entire p H range (p H=1,7,and 13).At p H=13,Fe-NC(Zn^(2+)) exhibited a half-wave potential (E1/2) of 0.95 V (vs.reversible hydrogen electrode),which was 70 m V higher than that of commercial Pt/C.More importantly,Fe-NC(Zn^(2+)) showed superior ORR stability in neutral media without performance loss after 5,000 cycles.A record-high open-circuit voltage(1.9 V) was obtained when Fe-NC(Zn^(2+)) was used as a cathodic catalyst in assembled Mg-air batteries in neutral media.The assembled liquid and all-solid Mg-air batteries with high performance indicated that Fe-NC(Zn^(2+)) has enormous potential for use in flexible and wearable Mg-air batteries.展开更多
Iron(Fe)was successfully doped in CuWO4 photoanode films with a combined liquid-phase spin-coating method via the dopant sources of Fe(NO3)3,FeSO4 and FeCl3.The microstructure of the prepared films was characterized b...Iron(Fe)was successfully doped in CuWO4 photoanode films with a combined liquid-phase spin-coating method via the dopant sources of Fe(NO3)3,FeSO4 and FeCl3.The microstructure of the prepared films was characterized by x-ray diffraction,scanning electron microscopy,and atomic force microscopy.The light absorption and photoelectric conversion properties were evaluated by the UV-visible absorption spectra and monochromatic incident photon-to-electron conversion efficiency.The chemical composition and element combination of the samples were examined by x-ray photoelectron spectroscopy.A linear sweep voltammetric and stability test(I-t)were performed with an electrochemical workstation.The results show that the samples are uniform with a thickness of approximately 800 nm and that the photoelectrochemical performance of the doped films is heavily dependent on the Fe source and dopant concentration.Upon optimizing the doping conditions of Fe(NO3)3 and the optimal source,the photocurrent density in the Fe-doped CuWO4 photoanode film is improved by 78%from 0.267 mA/cm2 to 0.476 mA/cm2 at 1.23 V vs reversible hydrogen electrode.The underlying causes are discussed.展开更多
The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, v...The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of Zn O nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved.The prepared nanostructures have been found to be nontoxic to SH-SY5 Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of Zn O nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.展开更多
The effect of Fe-doping on the magnetic properties of the ABO3-type perovskite cobaltites La0.7Ba0.3CoO3（0≤ y≤0.80） is reported. With no apparent structural change in any doped sample, the Curie temperature （Tc）...The effect of Fe-doping on the magnetic properties of the ABO3-type perovskite cobaltites La0.7Ba0.3CoO3（0≤ y≤0.80） is reported. With no apparent structural change in any doped sample, the Curie temperature （Tc） and the magnetization （M） are greatly suppressed for y ≤0.30 samples, while a distinct increase in Tc for the y=0.40 sample is observed. With the further increase of Fe concentration, Tc increases monotonically. Griffiths-like phases in 0.40≤y ≤0.60 samples are confirmed. The formation of the Griffiths-like phase is ascribed to B-site disordering induced isolation of ferromagnetic （FM） clusters above Tc.展开更多
The large single-crystal diamond with FeS doping along the （111） face is synthesized from the FeNi-C system by the temperature gradient method （TGM） under high-pressure and high-temperature （HPHT）. the effects o...The large single-crystal diamond with FeS doping along the （111） face is synthesized from the FeNi-C system by the temperature gradient method （TGM） under high-pressure and high-temperature （HPHT）. the effects of different FeS additive content on the shape, color, and quality of diamond are investigated. It is found that the （111） face of diamond is dominated and the （100） face of diamond disappears gradually with the increase of the FeS content. At the same time, the color of the diamond crystal changes from light yellow to gray-green and even gray-yellow. The stripes and pits corrosion on the diamond surface are observed to turn worse. The effects of FeS doping on the shape and surface morphology of diamond crystal are explained by the number of hang bonds in different surfaces of diamond. It can be shown from the test results of the Fourier transform infrared （FTIR） spectrum that there exists an S element in the obtained diamond. The N element content values in different additive amounts of diamond are calculated. The XPS spectrum results demonstrate that our obtained diamond contains S elements that exist in S-C and S-C-O forms in a diamond lattice. This work contributes to the further understanding and research of FeS-doped large single-crystal diamond characterization.展开更多
YBa2Cu3O7-d （YBCO）-coated conductors havewide-ranging potential in large-scale applications such assuperconducting maglev trains and superconducting electriccables, but low current carrying capability restrains thep...YBa2Cu3O7-d （YBCO）-coated conductors havewide-ranging potential in large-scale applications such assuperconducting maglev trains and superconducting electriccables, but low current carrying capability restrains thepractical application of YBCO-coated conductors at hightemperatures and high magnetic fields. It is crucial todevelop YBCO-coated conductors with high critical currentdensity. In this paper, epitaxial, dense, smooth, andcrack-free Fe-doped YBCO films were prepared on aLaAlO3 single crystal substrate via a fluorine-free polymerassistedmetal organic deposition method. The effects ofthe dilute Fe doping on microstructure and superconductingcharacter of YBCO films were investigated. The criticaltemperature for superconducting of the Fe-dopedYBCO films decreases slightly. However, the in-fieldcritical current density of YBCO films improves with diluteFe doping of amounts less than x = 0.005, compared to thepure YBCO film. Therefore, the current carrying capabilityof YBCO film can improve by doping with appropriateamounts of Fe. This means that dilute Fe doping in YBCOfilms may be a feasible way to prepare high-performancecoated conductors.展开更多
Surface engineering of active materials to generate desired energy state is critical to fabricate high-performance heterogeneous catalysts.However, its realization in a controllable level remains challenging. Using ox...Surface engineering of active materials to generate desired energy state is critical to fabricate high-performance heterogeneous catalysts.However, its realization in a controllable level remains challenging. Using oxygen evolution reaction(OER) as a model reaction, we report a surface-mediated Fe deposition strategy to electronically tailor surface energy states of porous Co_(3)O_(4)(Fe-pCo_(3)O_(4)) for enhanced activity towards OER. The Fe-pCo_(3)O_(4) exhibits a low overpotential of 280 mV to reach an OER current density of 100 mA cm^(-2), and a fast-kinetic behavior with a low Tafel slop of 58.2 mV dec^(-1), outperforming Co_(3)O_(4)-based OER catalysts recently reported and also the noble IrO_(2). The engineered material retains 100% of its original activity after operating at an overpotential of 350 m V for 100 h. A combination of theoretical calculations and experimental results finds out that the surface doped Fe promotes a high energy state and desired coordination environment in the near surface region, which enables optimized OER intermediates binding and favorably changes the rate-determining step.展开更多
基金supported by the National Natural Science Foundation of China(22171266)the FJIRSM&IUE Joint Research Fund(RHZX-2019-002)+2 种基金the STS Project(KFJ-STS-QYZD-2021-09002)the National Key Basic Research Program of China(2017YFA0403402)the Project of the National Natural Science Foundation of China(U1932119)。
文摘Fe/N/C catalysts,synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors,have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity in fuel cells and/or metal-air batteries.However,post-treatments (acid washing,second pyrolysis,and so on) are unavoidable to improve ORR catalytic activity and stability.The method for introducing Fe^(3+) sources (anhydrous Fe Cl_(3)) into the MOF structure,in particular,is a critical step that can avoid time-consuming post-treatments and result in more exposed Fe-N_(x) active sites.Herein,three different Fe doping strategies were systematically investigated to explore their influence on the types of active sites formed and ORR performance.Fe-NC(Zn^(2+)),synthesized by one-step pyrolysis of Fe doped ZIF-8 (Zn^(2+)) precursor which was obtained by adding the anhydrous Fe Cl_(3)source into the Zn(NO_(3))_(2)·6H_(2)O/methanol solution before mixing,possessed the highest Fe-N_(x)active sites due to the high-efficiency substitution of Zn^(2+)ions with Fe^(3+) ions during ZIF-8 growth,the strong interaction between Fe^(3+) ions and N atoms of 2-Methylimidazole (2-MIm),and ZIF-8’s micropore confinement effect.As a result,Fe-NC(Zn^(2+)) presented high ORR activity in the entire p H range (p H=1,7,and 13).At p H=13,Fe-NC(Zn^(2+)) exhibited a half-wave potential (E1/2) of 0.95 V (vs.reversible hydrogen electrode),which was 70 m V higher than that of commercial Pt/C.More importantly,Fe-NC(Zn^(2+)) showed superior ORR stability in neutral media without performance loss after 5,000 cycles.A record-high open-circuit voltage(1.9 V) was obtained when Fe-NC(Zn^(2+)) was used as a cathodic catalyst in assembled Mg-air batteries in neutral media.The assembled liquid and all-solid Mg-air batteries with high performance indicated that Fe-NC(Zn^(2+)) has enormous potential for use in flexible and wearable Mg-air batteries.
基金Project supported by the National Natural Science Foundation of China(Grant No.11204238)the Natural Science Foundation of Shaanxi Province,China(Grant No.2017JM1030).
文摘Iron(Fe)was successfully doped in CuWO4 photoanode films with a combined liquid-phase spin-coating method via the dopant sources of Fe(NO3)3,FeSO4 and FeCl3.The microstructure of the prepared films was characterized by x-ray diffraction,scanning electron microscopy,and atomic force microscopy.The light absorption and photoelectric conversion properties were evaluated by the UV-visible absorption spectra and monochromatic incident photon-to-electron conversion efficiency.The chemical composition and element combination of the samples were examined by x-ray photoelectron spectroscopy.A linear sweep voltammetric and stability test(I-t)were performed with an electrochemical workstation.The results show that the samples are uniform with a thickness of approximately 800 nm and that the photoelectrochemical performance of the doped films is heavily dependent on the Fe source and dopant concentration.Upon optimizing the doping conditions of Fe(NO3)3 and the optimal source,the photocurrent density in the Fe-doped CuWO4 photoanode film is improved by 78%from 0.267 mA/cm2 to 0.476 mA/cm2 at 1.23 V vs reversible hydrogen electrode.The underlying causes are discussed.
基金supported by Higher Education Commission of Pakistan, National Basic Research Program of China (2010CB934602)National Science Foundation of China (51171007 and 51271009)
文摘The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of Zn O nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved.The prepared nanostructures have been found to be nontoxic to SH-SY5 Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of Zn O nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.
基金Project supported by the National Basic Research Program of China (Grant No 2009CB929201)the National Natural Science Foundation of China (Grant No 10774179)
文摘The effect of Fe-doping on the magnetic properties of the ABO3-type perovskite cobaltites La0.7Ba0.3CoO3（0≤ y≤0.80） is reported. With no apparent structural change in any doped sample, the Curie temperature （Tc） and the magnetization （M） are greatly suppressed for y ≤0.30 samples, while a distinct increase in Tc for the y=0.40 sample is observed. With the further increase of Fe concentration, Tc increases monotonically. Griffiths-like phases in 0.40≤y ≤0.60 samples are confirmed. The formation of the Griffiths-like phase is ascribed to B-site disordering induced isolation of ferromagnetic （FM） clusters above Tc.
基金Project supported by the National Natural Science Foundation of China(Grant No.51772120)the Project for Key Science and Technology Research of Henan Province,China(Grant Nos.162102210275 and 172102210283)+1 种基金the Key Scientific Research Project in Colleges and Universities of Henan Province,China(Grant Nos.18A430017 and 17A430020)the Professional Practice Demonstration Base for Professional Degree Graduate in Material Engineering of Henan Polytechnic University,China(Grant No.2016YJD03)
文摘The large single-crystal diamond with FeS doping along the （111） face is synthesized from the FeNi-C system by the temperature gradient method （TGM） under high-pressure and high-temperature （HPHT）. the effects of different FeS additive content on the shape, color, and quality of diamond are investigated. It is found that the （111） face of diamond is dominated and the （100） face of diamond disappears gradually with the increase of the FeS content. At the same time, the color of the diamond crystal changes from light yellow to gray-green and even gray-yellow. The stripes and pits corrosion on the diamond surface are observed to turn worse. The effects of FeS doping on the shape and surface morphology of diamond crystal are explained by the number of hang bonds in different surfaces of diamond. It can be shown from the test results of the Fourier transform infrared （FTIR） spectrum that there exists an S element in the obtained diamond. The N element content values in different additive amounts of diamond are calculated. The XPS spectrum results demonstrate that our obtained diamond contains S elements that exist in S-C and S-C-O forms in a diamond lattice. This work contributes to the further understanding and research of FeS-doped large single-crystal diamond characterization.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education (200806131034, 200806130023)Natural Science Foundation of China under Contract Nos. 50672078 and 50872116+6 种基金the National Science Fund for Distinguished Young Scholars under Contract No. 50588201, and 51102199the National High-Tech Program of China (863 Program) under Contract No. 2007AA03Z203the PCSIRT of the Ministry of Education of China (IRT0751)Research and Development Foundation of Southwest Jiao tong University under Grant Contract No. 2004A02Fundamental Research Funds for the Central Universities (SWJTU12CX019)the National Natural Science Foundation (51202202)Fundamental Research Funds for the Central Universities of China (SWJTU2682013CX005)
文摘YBa2Cu3O7-d （YBCO）-coated conductors havewide-ranging potential in large-scale applications such assuperconducting maglev trains and superconducting electriccables, but low current carrying capability restrains thepractical application of YBCO-coated conductors at hightemperatures and high magnetic fields. It is crucial todevelop YBCO-coated conductors with high critical currentdensity. In this paper, epitaxial, dense, smooth, andcrack-free Fe-doped YBCO films were prepared on aLaAlO3 single crystal substrate via a fluorine-free polymerassistedmetal organic deposition method. The effects ofthe dilute Fe doping on microstructure and superconductingcharacter of YBCO films were investigated. The criticaltemperature for superconducting of the Fe-dopedYBCO films decreases slightly. However, the in-fieldcritical current density of YBCO films improves with diluteFe doping of amounts less than x = 0.005, compared to thepure YBCO film. Therefore, the current carrying capabilityof YBCO film can improve by doping with appropriateamounts of Fe. This means that dilute Fe doping in YBCOfilms may be a feasible way to prepare high-performancecoated conductors.
基金financially supported by National Natural Science Foundation of China (21972102)Natural Science Foundation of Jiangsu province (BK20200991)+3 种基金Suzhou Science and Technology Planning Project (SS202016)Jiangsu Laboratory for Biochemical Sensing and BiochipJiangsu Key Laboratory for Micro and Nano Heat Fluid Flow Technology and Energy ApplicationCollaborative Innovation Center of Water Treatment Technology & Material。
文摘Surface engineering of active materials to generate desired energy state is critical to fabricate high-performance heterogeneous catalysts.However, its realization in a controllable level remains challenging. Using oxygen evolution reaction(OER) as a model reaction, we report a surface-mediated Fe deposition strategy to electronically tailor surface energy states of porous Co_(3)O_(4)(Fe-pCo_(3)O_(4)) for enhanced activity towards OER. The Fe-pCo_(3)O_(4) exhibits a low overpotential of 280 mV to reach an OER current density of 100 mA cm^(-2), and a fast-kinetic behavior with a low Tafel slop of 58.2 mV dec^(-1), outperforming Co_(3)O_(4)-based OER catalysts recently reported and also the noble IrO_(2). The engineered material retains 100% of its original activity after operating at an overpotential of 350 m V for 100 h. A combination of theoretical calculations and experimental results finds out that the surface doped Fe promotes a high energy state and desired coordination environment in the near surface region, which enables optimized OER intermediates binding and favorably changes the rate-determining step.
