One-dimensional(1D, wire-and fiber-shaped)supercapacitors have recently attracted interest due to their roll-up, micrometer size and potential applications in portable or wearable electronics. Herein, a 1D wireshaped ...One-dimensional(1D, wire-and fiber-shaped)supercapacitors have recently attracted interest due to their roll-up, micrometer size and potential applications in portable or wearable electronics. Herein, a 1D wireshaped electrode was developed based on Fe_3O_4 nanosheet arrays connected on the Fe wire, which was prepared via oxidation of Fe wire in 0.1 M KCl solution(pH 3) with O2-rich environment under 70 °C. The obtained Fe_3O_4 nanosheet arrays displayed a high specific capacitance(20.8 m F cm^(-1) at 10 mV s^(-1)) and long cycling lifespan(91.7% retention after 2500 cycles). Theexcellent performance may attribute to the connected nanosheet structure with abundant open spaces and the intimate contact between the Fe_3O_4 and iron substrate. In addition, a wire-shaped asymmetric supercapacitor was fabricated and had excellent capacitive properties with a high energy density(9 l Wh cm^(-2)) at power density of 532.7 l W cm^(-2) and remarkable long-term cycling performance(99% capacitance retention after 2000 cycles).Considering low cost and earth-abundant electrode material, as well as outstanding electrochemical properties, the assembled supercapacitor will possess enormous potential for practical applications in portable electronic device.展开更多
A magnetic sensor for detection of Pb^2＋ has been developed based on Fe/Fe3O4 nanoparticles modified by3-（3,4-dihydroxyphenyl）propionic acid（DHCA）. The carboxyl groups of DHCA have a strong affinity to coordinati...A magnetic sensor for detection of Pb^2＋ has been developed based on Fe/Fe3O4 nanoparticles modified by3-（3,4-dihydroxyphenyl）propionic acid（DHCA）. The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb^2＋ thus inducing the transformation of Fe/Fe3O4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time（T2） of the surrounding water protons. Upon addition of the different concentrations of Pb^2＋ to an aq. solution of DHCA functionalized Fe/Fe3O4 nanoparticles（DHCA-Fe/Fe3O4 NPs）（[Fe] = 90 mmol/L）, the change of T2 values display a good linear relationship with the concentration of Pb^2＋ from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb^2＋, DHCA-Fe/Fe3O4 NPs exhibited a high selectivity over other metal ions.展开更多
Ni/Fe-Fe3O4 nanocomposites were synthesized for dechlorination of 2,4-dichlorophenol （2,4-DCP）. The effects of the Ni content in Ni/Fe-Fe3O4 nanocomposites, solution pH, and common dissolved ions on the dechlorinati...Ni/Fe-Fe3O4 nanocomposites were synthesized for dechlorination of 2,4-dichlorophenol （2,4-DCP）. The effects of the Ni content in Ni/Fe-Fe3O4 nanocomposites, solution pH, and common dissolved ions on the dechlorination efficiency were investigated, in addition to the reusability of the nanocomposites. The results showed that increasing content of Ni in Ni/Fe-FesO4 nanocomposites, from 1 to 5 wt.%, greatly increased the dechlorination efficiency; the Ni/Fe-Fe3O4 nanocomposites had much higher dechlorination efficiency than bare Ni/Fe nanoparticles. Ni content of S wt.% and initial pH below 6.0 was found to be the optimal conditions for the catalytic dechlorination of 2,4-DCP. Both 2,4-DCP and the intermediate product 2-chlorophenol （2-CP） were completely removed, and the concentra- tion of the final product phenol was close to the theoretical phenol production from complete dechlorination of 20 mg/L of 2,4-DCP, after 3 hr reaction at initial pH value of 6.0, 3 g/L Ni/Fe-Fe3O4, S wt.% Ni content in the composite, and temperature of 22℃ 2,4-DCP dechlorination was enhanced by C1- and inhibited by NO3- and SO42-. The nanocomposites were easily separated from the solution by an applied magnetic field. When the catalyst was reused, the removal efficiency of 2,4-DCP was almost 100% for the first seven uses, and gradually decreased to 75% in cycles 8-10. Therefore, the Ni/Fe-Fe3O4 nanocomposites can be considered as a potentially effective tool for remediation of Pollution bv 2.4-DCP.展开更多
Magnetic Fe^0/Fe3O4/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N2 sorption–desorption, scan...Magnetic Fe^0/Fe3O4/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N2 sorption–desorption, scanning electron microscopy（SEM）, Fourier transform infrared spectroscopy（FT-IR）, vibrating-sample magnetometer（VSM） measurements and X-ray photoelectron spectroscopy（XPS）. The results indicated that Fe^0/Fe3O4/graphene had a layered structure with Fe crystals highly dispersed in the interlayers of graphene, which could enhance the mass transfer process between Fe^0/Fe3O4/graphene and pollutants. Fe^0/Fe3O4/graphene exhibited ferromagnetism and could be easily separated and re-dispersed for reuse in water. Typical dyes, such as Methyl Orange, Methylene Blue and Crystal Violet, could be decolorized by Fe^0/Fe3O4/graphene rapidly. After 20 min, the decolorization efficiencies of methyl orange, methylene blue and crystal violet were 94.78%, 91.60% and 89.07%, respectively. The reaction mechanism of Fe^0/Fe3O4/graphene with dyes mainly included adsorption and enhanced reduction by the composite. Thus, Fe^0/Fe3O4/graphene prepared by the one-step reduction method has excellent performance in removal of dyes in water.展开更多
基金supported by Zhujiang New Stars of Science and Technology (2014J2200061)
文摘One-dimensional(1D, wire-and fiber-shaped)supercapacitors have recently attracted interest due to their roll-up, micrometer size and potential applications in portable or wearable electronics. Herein, a 1D wireshaped electrode was developed based on Fe_3O_4 nanosheet arrays connected on the Fe wire, which was prepared via oxidation of Fe wire in 0.1 M KCl solution(pH 3) with O2-rich environment under 70 °C. The obtained Fe_3O_4 nanosheet arrays displayed a high specific capacitance(20.8 m F cm^(-1) at 10 mV s^(-1)) and long cycling lifespan(91.7% retention after 2500 cycles). Theexcellent performance may attribute to the connected nanosheet structure with abundant open spaces and the intimate contact between the Fe_3O_4 and iron substrate. In addition, a wire-shaped asymmetric supercapacitor was fabricated and had excellent capacitive properties with a high energy density(9 l Wh cm^(-2)) at power density of 532.7 l W cm^(-2) and remarkable long-term cycling performance(99% capacitance retention after 2000 cycles).Considering low cost and earth-abundant electrode material, as well as outstanding electrochemical properties, the assembled supercapacitor will possess enormous potential for practical applications in portable electronic device.
基金supported by National Natural Science Foundation of China (Nos. 21271130 and 21371122)Shanghai Science and Technology Development Fund (Nos. 12ZR1421800 and 13520502800)International Joint Laboratory on Resource Chemistry (IJLRC)
文摘A magnetic sensor for detection of Pb^2＋ has been developed based on Fe/Fe3O4 nanoparticles modified by3-（3,4-dihydroxyphenyl）propionic acid（DHCA）. The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb^2＋ thus inducing the transformation of Fe/Fe3O4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time（T2） of the surrounding water protons. Upon addition of the different concentrations of Pb^2＋ to an aq. solution of DHCA functionalized Fe/Fe3O4 nanoparticles（DHCA-Fe/Fe3O4 NPs）（[Fe] = 90 mmol/L）, the change of T2 values display a good linear relationship with the concentration of Pb^2＋ from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb^2＋, DHCA-Fe/Fe3O4 NPs exhibited a high selectivity over other metal ions.
基金supported by the National High Technology Research and Development Program of China (863 Program) (No. 2013AA06A305)the Science Project of Zhejiang Province (No. 2013C31107)the Science Project of Jiaxing City (No. 2014AY21018)
文摘Ni/Fe-Fe3O4 nanocomposites were synthesized for dechlorination of 2,4-dichlorophenol （2,4-DCP）. The effects of the Ni content in Ni/Fe-Fe3O4 nanocomposites, solution pH, and common dissolved ions on the dechlorination efficiency were investigated, in addition to the reusability of the nanocomposites. The results showed that increasing content of Ni in Ni/Fe-FesO4 nanocomposites, from 1 to 5 wt.%, greatly increased the dechlorination efficiency; the Ni/Fe-Fe3O4 nanocomposites had much higher dechlorination efficiency than bare Ni/Fe nanoparticles. Ni content of S wt.% and initial pH below 6.0 was found to be the optimal conditions for the catalytic dechlorination of 2,4-DCP. Both 2,4-DCP and the intermediate product 2-chlorophenol （2-CP） were completely removed, and the concentra- tion of the final product phenol was close to the theoretical phenol production from complete dechlorination of 20 mg/L of 2,4-DCP, after 3 hr reaction at initial pH value of 6.0, 3 g/L Ni/Fe-Fe3O4, S wt.% Ni content in the composite, and temperature of 22℃ 2,4-DCP dechlorination was enhanced by C1- and inhibited by NO3- and SO42-. The nanocomposites were easily separated from the solution by an applied magnetic field. When the catalyst was reused, the removal efficiency of 2,4-DCP was almost 100% for the first seven uses, and gradually decreased to 75% in cycles 8-10. Therefore, the Ni/Fe-Fe3O4 nanocomposites can be considered as a potentially effective tool for remediation of Pollution bv 2.4-DCP.
基金supported by the Fundamental Research Funds for Central Universities and Research Funds of Renmin University of China(Nos.14XLNQ02,15XNLD04)
文摘Magnetic Fe^0/Fe3O4/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N2 sorption–desorption, scanning electron microscopy（SEM）, Fourier transform infrared spectroscopy（FT-IR）, vibrating-sample magnetometer（VSM） measurements and X-ray photoelectron spectroscopy（XPS）. The results indicated that Fe^0/Fe3O4/graphene had a layered structure with Fe crystals highly dispersed in the interlayers of graphene, which could enhance the mass transfer process between Fe^0/Fe3O4/graphene and pollutants. Fe^0/Fe3O4/graphene exhibited ferromagnetism and could be easily separated and re-dispersed for reuse in water. Typical dyes, such as Methyl Orange, Methylene Blue and Crystal Violet, could be decolorized by Fe^0/Fe3O4/graphene rapidly. After 20 min, the decolorization efficiencies of methyl orange, methylene blue and crystal violet were 94.78%, 91.60% and 89.07%, respectively. The reaction mechanism of Fe^0/Fe3O4/graphene with dyes mainly included adsorption and enhanced reduction by the composite. Thus, Fe^0/Fe3O4/graphene prepared by the one-step reduction method has excellent performance in removal of dyes in water.
