Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal...Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.展开更多
Alkaline zinc manganese dioxide（Zn–MnO2）batteries are widely used in everyday life. Recycling of waste alkaline Zn–MnO2 batteries has always been a hot environmental concern. In this study, a simple and costeffect...Alkaline zinc manganese dioxide（Zn–MnO2）batteries are widely used in everyday life. Recycling of waste alkaline Zn–MnO2 batteries has always been a hot environmental concern. In this study, a simple and costeffective process for synthesizing Mn3O4/carbon nanotube（CNT） nanocomposites from recycled alkaline Zn–MnO2 batteries is presented. Manganese oxide was recovered from spent Zn–MnO2 battery cathodes. The Mn3O4/CNT nanocomposites were produced by ball milling the recovered manganese oxide in a commercial multi-wall carbon nanotubes（MWCNTs） solution. Scanning electron microscopy（SEM） analysis demonstrates that the nanocomposite has a unique three-dimensional（3D） bird nest structure. Mn3O4 nanoparticles are homogeneously distributed on MWCNT framework. Mn3O4/CNT nanocomposites were evaluated as an anode material for lithium-ion batteries, exhibiting a highly reversible specific capacitance of -580 mA h·g^-1 after 100 cycles. Moreover, Mn3O4/CNT nanocomposite also shows a fairly positive onset potential of -0.15 V and quite high oxygen reducibility when considered as an electrocatalyst for oxygen reduction reaction.展开更多
MnO2-impregnated carbon-coated Fe3 O4(Fe3O4/C/MnO2)nanocomposites with a good core-shell structure were prepared by direct oxidation of carbon-coated Fe3 O4(Fe3O4/C)microspheres with KMnO4 in alkaline solution and app...MnO2-impregnated carbon-coated Fe3 O4(Fe3O4/C/MnO2)nanocomposites with a good core-shell structure were prepared by direct oxidation of carbon-coated Fe3 O4(Fe3O4/C)microspheres with KMnO4 in alkaline solution and applied to adsorb bovine serum albumin(BSA).X-ray diffraction(XRD),transmission electron microscope(TEM),Fourier transform infrared spectrometer(FTIR),vibrating sample magnetometer(VSM)and thermogravimetric analyzer(TGA)tests show that Fe3O4/C microspheres were newly functionalized via the oxidation by KMnO4.Fe3O4/C/MnO2 nanocomposites exhibit a higher adsorption capacity for BSA than Fe3O4/C microspheres and the maximum adsorption of BSA on them occurs at pH 4.7,which is the isoelectric point of BSA.Langmuir isotherm model describes the adsorption of BSA better than Freundlich model and Temkin model,and the kinetics data fit well with the pseudo-second-order model.展开更多
The hydrogen storage properties of the nanocomposite Mg 95 Ni 3(MnO 2) 2 (mass fraction, %) were studied. The temperature changes in hydriding/dehydriding process were investigated. The nanocomposite was fabricated by...The hydrogen storage properties of the nanocomposite Mg 95 Ni 3(MnO 2) 2 (mass fraction, %) were studied. The temperature changes in hydriding/dehydriding process were investigated. The nanocomposite was fabricated by ball milling process of mixed elemental Mg, Ni and oxide maganese MnO 2 under hydrogen pressure (approximately 0.6?MPa). The hydrogen absorption and desorption properties of the samples milled for various times were investigated. A remarkable enhancement of hydrogen absorption kinetics and low operational desorption temperature have been found after the sample milled for over 57?h. For example, this nanocomposite can absorb hydrogen more than 6.0% (mass fraction) in 60?s at 200?℃ under 2.0?MPa, and desorption capacity also exceeds 6.0% (mass fraction) in 400?s at 310?℃ under 0.1?MPa. The storage properties of samples milled for various times were studied and the kinetics of the samples were analyzed.展开更多
In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way.Multiple experiments were carried out to optimi...In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way.Multiple experiments were carried out to optimize the oxidation of basic dye（Methylene Blue（MB））,including the molar ratio of MnO2to chloroauric acid（HAu Cl4）,the p H of the solution and the effect of initial material.Under the optimal condition,the highest degradation efficiency for MB achieved to 98.9%within 60 min,which was obviously better than commercial MnO2powders（4.3%）and MnO2nanosheets（74.2%）.The enhanced oxidative degradation might attribute to the in-situ generation of ultra-small and highly-dispersed Au-NPs which enlarged the synergistic effect and/or interfacial effect between MnO2nanosheets and Au-NPs and facilitated the uptake of electrons by MnO2from MB during the oxidation,thus validating the application of MnO2/Au-NPs nanocomposite for direct removal of organic dyes from wastewater in a simple and convenient fashion.展开更多
MnO2/carbon nanocomposites with hierarchical pore structure and controllable MnO2 loading have been synthesized using a self-limiting growth method. This was achieved by the redox reactions of KMnO4 with sacrificed ca...MnO2/carbon nanocomposites with hierarchical pore structure and controllable MnO2 loading have been synthesized using a self-limiting growth method. This was achieved by the redox reactions of KMnO4 with sacrificed carbon substrates that contain hierarchical pores. The unique pore structure allows the synthesis of nanocomposites with tunable MnO2 loading up to 83 wt.%. The specific capacitance of the nanocomposites increased with the MnO2 loading; the conductivity measured by electrochemical impedance spectroscopy, on the other hand, decreased with increasing MnO2 loading. Optimization of the MnO2 loading resulted in nanocomposites with high specific capacitance and excellent rate capability. This work provides important fundamental understanding which will facilitate the design and fabrication of high-performance supercapacitor materials for a large variety of applications.展开更多
In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐source...In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐sourced reducing agent,without stabilizers or surfactants.This synthetic process is environmentally‐friendly and avoids the use of toxic reducing agents.Phenolic hydroxyl groups in the leaf extract are believed to reduce Cu2+in solution to generate Cu NPs that are subsequently stabilized on the MnO2NP surfaces.The resulting Cu/MnO2nanocomposite was fully characterized using X‐ray diffraction,transmission electron microscopy,field emission scanning electron microscopy,energy‐dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy.This material was found to function as a highly active,efficient and recyclable heterogeneous catalyst for the reduction of Congo red,rhodamine B and methylene blue as well as nitro compounds such as2,4‐dinitrophenylhydrazine and4‐nitrophenol in the presence of NaBH4in aqueous media at ambient temperature.The high stability of the Cu/MnO2nanocomposite also allows the catalyst to be separated and reused several times without any significant loss of activity.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.展开更多
Over the past 2 years,many DNA motors have been synthesized and run in living cells,but there are still challenges in designing integrated DNA motors self-powered to enable autonomous intracellular walking without aux...Over the past 2 years,many DNA motors have been synthesized and run in living cells,but there are still challenges in designing integrated DNA motors self-powered to enable autonomous intracellular walking without auxiliary additives.Herein,we report a smart strategy based on a DNA motor–MnO2 nanocomposite,which successfully meets these requirements of intracellular analysis and enables sensitive imaging of specific microRNAs(miRNAs)in living cells.展开更多
基金Projects(21071153,20976198)supported by the National Natural Science Foundation of China
文摘Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.
基金financially supported by the National Natural Science Foundation of China(Nos.21671096 and 21603094)the Shenzhen Peacock Plan(No.KQCX2014052215 0815065)+1 种基金the Natural Science Foundation of Shenzhen(Nos.JCYJ20150630145302231 and JCYJ20150331101823677)the Science and Technology Innovation Foundation for the Undergraduates of South University of Science and Technology of China(Nos.2016S10,2016S20,2015x19 and 2015x12)
文摘Alkaline zinc manganese dioxide（Zn–MnO2）batteries are widely used in everyday life. Recycling of waste alkaline Zn–MnO2 batteries has always been a hot environmental concern. In this study, a simple and costeffective process for synthesizing Mn3O4/carbon nanotube（CNT） nanocomposites from recycled alkaline Zn–MnO2 batteries is presented. Manganese oxide was recovered from spent Zn–MnO2 battery cathodes. The Mn3O4/CNT nanocomposites were produced by ball milling the recovered manganese oxide in a commercial multi-wall carbon nanotubes（MWCNTs） solution. Scanning electron microscopy（SEM） analysis demonstrates that the nanocomposite has a unique three-dimensional（3D） bird nest structure. Mn3O4 nanoparticles are homogeneously distributed on MWCNT framework. Mn3O4/CNT nanocomposites were evaluated as an anode material for lithium-ion batteries, exhibiting a highly reversible specific capacitance of -580 mA h·g^-1 after 100 cycles. Moreover, Mn3O4/CNT nanocomposite also shows a fairly positive onset potential of -0.15 V and quite high oxygen reducibility when considered as an electrocatalyst for oxygen reduction reaction.
基金financially supported by the National Science and Technology Major Project of China for Water Pollution Control and Treatment(No.2013ZX07202-010)。
文摘MnO2-impregnated carbon-coated Fe3 O4(Fe3O4/C/MnO2)nanocomposites with a good core-shell structure were prepared by direct oxidation of carbon-coated Fe3 O4(Fe3O4/C)microspheres with KMnO4 in alkaline solution and applied to adsorb bovine serum albumin(BSA).X-ray diffraction(XRD),transmission electron microscope(TEM),Fourier transform infrared spectrometer(FTIR),vibrating sample magnetometer(VSM)and thermogravimetric analyzer(TGA)tests show that Fe3O4/C microspheres were newly functionalized via the oxidation by KMnO4.Fe3O4/C/MnO2 nanocomposites exhibit a higher adsorption capacity for BSA than Fe3O4/C microspheres and the maximum adsorption of BSA on them occurs at pH 4.7,which is the isoelectric point of BSA.Langmuir isotherm model describes the adsorption of BSA better than Freundlich model and Temkin model,and the kinetics data fit well with the pseudo-second-order model.
文摘The hydrogen storage properties of the nanocomposite Mg 95 Ni 3(MnO 2) 2 (mass fraction, %) were studied. The temperature changes in hydriding/dehydriding process were investigated. The nanocomposite was fabricated by ball milling process of mixed elemental Mg, Ni and oxide maganese MnO 2 under hydrogen pressure (approximately 0.6?MPa). The hydrogen absorption and desorption properties of the samples milled for various times were investigated. A remarkable enhancement of hydrogen absorption kinetics and low operational desorption temperature have been found after the sample milled for over 57?h. For example, this nanocomposite can absorb hydrogen more than 6.0% (mass fraction) in 60?s at 200?℃ under 2.0?MPa, and desorption capacity also exceeds 6.0% (mass fraction) in 400?s at 310?℃ under 0.1?MPa. The storage properties of samples milled for various times were studied and the kinetics of the samples were analyzed.
基金supported by the National Natural Science Foundation of China (Nos. 21277048 and 21505046)the China Postdoctoral Science Foundation (No. 2016 M590336)+1 种基金the "Chenguang Program" funded by Shanghai Education Development FoundationShanghai Municipal Education Commission (No. 15CG21)
文摘In this work,the gold nanoparticles（Au-NPs）were in-situ generated on the surface of MnO2nanosheets to form MnO2/Au-NPs nanocomposite in a simple and cost-effective way.Multiple experiments were carried out to optimize the oxidation of basic dye（Methylene Blue（MB））,including the molar ratio of MnO2to chloroauric acid（HAu Cl4）,the p H of the solution and the effect of initial material.Under the optimal condition,the highest degradation efficiency for MB achieved to 98.9%within 60 min,which was obviously better than commercial MnO2powders（4.3%）and MnO2nanosheets（74.2%）.The enhanced oxidative degradation might attribute to the in-situ generation of ultra-small and highly-dispersed Au-NPs which enlarged the synergistic effect and/or interfacial effect between MnO2nanosheets and Au-NPs and facilitated the uptake of electrons by MnO2from MB during the oxidation,thus validating the application of MnO2/Au-NPs nanocomposite for direct removal of organic dyes from wastewater in a simple and convenient fashion.
文摘MnO2/carbon nanocomposites with hierarchical pore structure and controllable MnO2 loading have been synthesized using a self-limiting growth method. This was achieved by the redox reactions of KMnO4 with sacrificed carbon substrates that contain hierarchical pores. The unique pore structure allows the synthesis of nanocomposites with tunable MnO2 loading up to 83 wt.%. The specific capacitance of the nanocomposites increased with the MnO2 loading; the conductivity measured by electrochemical impedance spectroscopy, on the other hand, decreased with increasing MnO2 loading. Optimization of the MnO2 loading resulted in nanocomposites with high specific capacitance and excellent rate capability. This work provides important fundamental understanding which will facilitate the design and fabrication of high-performance supercapacitor materials for a large variety of applications.
文摘In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐sourced reducing agent,without stabilizers or surfactants.This synthetic process is environmentally‐friendly and avoids the use of toxic reducing agents.Phenolic hydroxyl groups in the leaf extract are believed to reduce Cu2+in solution to generate Cu NPs that are subsequently stabilized on the MnO2NP surfaces.The resulting Cu/MnO2nanocomposite was fully characterized using X‐ray diffraction,transmission electron microscopy,field emission scanning electron microscopy,energy‐dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy.This material was found to function as a highly active,efficient and recyclable heterogeneous catalyst for the reduction of Congo red,rhodamine B and methylene blue as well as nitro compounds such as2,4‐dinitrophenylhydrazine and4‐nitrophenol in the presence of NaBH4in aqueous media at ambient temperature.The high stability of the Cu/MnO2nanocomposite also allows the catalyst to be separated and reused several times without any significant loss of activity.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.
基金support from the National Key R&D Program of China(grant no.2016YFA0201200)the National Natural Science Foundation of China(grant no.21991080)the Excellent Research Program of Nanjing University(ZYJH004).
文摘Over the past 2 years,many DNA motors have been synthesized and run in living cells,but there are still challenges in designing integrated DNA motors self-powered to enable autonomous intracellular walking without auxiliary additives.Herein,we report a smart strategy based on a DNA motor–MnO2 nanocomposite,which successfully meets these requirements of intracellular analysis and enables sensitive imaging of specific microRNAs(miRNAs)in living cells.
